"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:0efc4707-eceb-49bc-9f9d-52027ec82673","http://resolver.tudelft.nl/uuid:0efc4707-eceb-49bc-9f9d-52027ec82673","Quantifying and modelling the effect of external and internal vegetation water dynamics on radar data","Khabbazan, S. (TU Delft Mathematical Geodesy and Positioning)","Steele-Dunne, S.C. (promotor); Lopez Dekker, F.J. (copromotor); Delft University of Technology (degree granting institution)","2024","Agriculture plays a critical role in the economy and environment worldwide, and the provision of real-time, reliable information on large-scale agricultural activity is essential for precision agriculture and global economic prosperity. In this context, remote sensing, especially through Synthetic Aperture Radar (SAR), can play an important role by offering accurate estimation of crop biophysical parameters such as Leaf Area Index (LAI), crop height, dry biomass, and Vegetation Water Content (VWC). Unlike traditional high-resolution optical imagery, which is often undermined by cloud cover, SAR microwave remote sensing overcomes these limitations by generating and transmitting longer wavelengths (300MHz – 10 GHz) that penetrate clouds and aerosols and allowing data acquisition both day and night. However, SAR data is influenced by various factors such as sensor characteristics such as frequency, polarization, and incidence angle, as well as target characteristics like the size and shape distribution of crop constituents, and more importantly, the water content of crop constituents. In the path towards precision farming and more sustainable and efficient farming using SAR data, understanding the role of these factors, particularly the dynamics of external and internal vegetation water content on radar backscatter, is vital.
To date, however, the potentially confounding effects of both internal and, particularly, external water dynamics in vegetation on radar backscatter have not been adequately addressed. Existing studies have indeed illustrated the effects of SCW on radar backscatter, but the degree to which it influences different frequencies and polarizations, and the subsequent impact on crop bio-geophysical parameters remains unclear. Therefore, the main goal of this thesis is to expand our knowledge of the relationship between radar backscatter, vegetation dynamics, and surface canopy water (SCW) in agricultural monitoring. In this thesis we utilized statistical analysis and radiative transfer modeling in combination with fully polarimetric L-band data from a truck-mounted scatterometer and C-band data from Sentinel-1, along with extensive field data…
In this study, we utilize publicly available geospatial data to identify changes in land use, vegetation classification and spectral indicators of vegetation health at restoration sites associated with the Room for the River (RftR) program in the Netherlands. Completed in 2018, RftR involved over 30 river management projects constructed to reduce flood risk by lowering peak water levels (Mosselman, 2022).
Our objective is to quantify the impact of ecologically focused RftR projects on habitat heterogeneity and river connectivity in the surrounding floodplains.","river restoration; remote sensing; GIS; biodiversity; Normalized Difference Vegetation Index (NDVI); vegetation classification","en","abstract","","","","","","","","","","","Rivers, Ports, Waterways and Dredging Engineering","","",""
"uuid:d4c2f44f-2429-4c7a-835b-9792e58541e2","http://resolver.tudelft.nl/uuid:d4c2f44f-2429-4c7a-835b-9792e58541e2","Evaluating real-world emissions from in-use buses and taxis using on-road remote sensing","Middela, Mounisai Siddartha (Trinity College Dublin); Mahesh, S. (TU Delft Transport and Planning); McNabola, Aonghus (Trinity College Dublin); Smith, William (University College Dublin); Timoney, David (University College Dublin); Ekhtiari, Ali (University College Dublin); Fowler, Ben (Ricardo Energy and Environment); Willis, Paul (Ricardo Energy and Environment); Rose, Rebecca (Ricardo Energy and Environment)","","2024","Assessing real-world emissions from buses and taxis is vital to comprehend their impact on urban air quality. Such vehicles differ significantly from the majority of the fleet owing to their higher mileage rates. However, few studies have focused on specifically assessing the emissions from this segment of the vehicle fleet. In this context, this study evaluated the real-world emissions of nitrogen oxides (NOx) from in-use buses and taxis in Dublin, Ireland, using crossroad remote sensing technology. The remote sensing system was deployed at strategic locations throughout the city to capture on-road emissions from passing vehicles. The collected data included vehicle related information such as emission standard, make, and mileage, and pollutants including NOx. Based on this data, analysis was aimed to understand the impact of Euro emission standard, ambient temperature, mileage, and make of the vehicle on NOx emissions. The results reveal that the average emissions from taxis reduce by 37% from Euro 5 to Euro 6b, and average emissions from Euro 6 buses are 87% lower compared to Euro 5. The trends in emission factors (EFs) of buses and taxis were similar during summer and winter sampling. Moreover, on comparing the emissions from the top five taxi manufacturers, different trends in the emission factors were observed. Finally, the study found that the effect of vehicle mileage on emissions was unclear for both buses and taxis. In any case, these findings provide valuable insights into the real-world emission performance of the existing fleet of buses and taxis in Dublin and highlight the need for targeted measures to reduce emissions from these vehicles. The results can assist policymakers and urban planners in formulating evidence-based strategies to improve air quality in Dublin and other cities facing similar challenges.","Buses; Euro-6 regulation; In-use surveillance; On-road vehicle emissions; Remote sensing; Taxis","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-07-08","","","Transport and Planning","","",""
"uuid:cc6842c0-23d3-40c6-be10-f93f8dee55fc","http://resolver.tudelft.nl/uuid:cc6842c0-23d3-40c6-be10-f93f8dee55fc","Integrating post-event very high resolution SAR imagery and machine learning for building-level earthquake damage assessment","Macchiarulo, V. (TU Delft Geo-engineering); Giardina, Giorgia (TU Delft Geo-engineering); Milillo, Pietro (University of Houston; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)); Aktas, Yasemin D. (University College London (UCL)); Whitworth, Michael R.Z. (AECOM Technology Corporation, United Kingdom)","","2024","Earthquakes have devastating effects on densely urbanised regions, requiring rapid and extensive damage assessment to guide resource allocation and recovery efforts. Traditional damage assessment is time-consuming, resource-intensive, and faces challenges in covering vast affected areas, often limiting timely decision-making. Space-borne synthetic aperture radars (SAR) have gained attention for their all-weather and day-night imaging capabilities. These advantages, coupled with wide coverage, short revisits and very high resolution (VHR), have created opportunities for using SAR data in disaster response. However, most SAR studies for post-earthquake damage assessment rely on change detection methods using pre-event SAR images, which are often unavailable in operational scenarios. Limited studies using solely post-event SAR data primarily concentrate on city-block-level damage assessment, thus not fully exploiting the VHR SAR potential. This paper presents a novel method integrating solely post-event VHR SAR imagery and machine learning (ML) for regional-scale post-earthquake damage assessment at the individual building-level. We first used supervised learning on case-specific datasets, and then introduced a combined learning approach, incorporating inventories from multiple case studies to assess generalisation. Finally, the ML model was tested on unseen study areas, to evaluate its flexibility in unfamiliar contexts. The method was implemented using datasets collected during the Earthquake Engineering Field Investigation Team (EEFIT) reconnaissance missions following the 2021 Nippes earthquake and the 2023 Kahramanmaraş earthquake sequence. The results demonstrate the method’s ability to classify standing and collapsed buildings, achieving up to 72% overall accuracy on unseen regions. The proposed method has potential for future disaster assessments, thereby contributing to more effective earthquake management strategies.","Disaster management; ML techniques; Post-earthquake reconnaissance; Remote sensing; Synthetic aperture radar; Texture analysis","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:fbdc679c-cbe5-4cd0-8783-972b3636fa53","http://resolver.tudelft.nl/uuid:fbdc679c-cbe5-4cd0-8783-972b3636fa53","City-scale damage assessment using very-high-resolution SAR satellite imagery and building survey data for the 2021 Haiti earthquake","Macchiarulo, V. (TU Delft Geo-engineering); Foroughnia, Fatemeh (TU Delft Geo-engineering); Milillo, Pietro (University of Houston); Whitworth, Michael R. Z. (AECOM Ltd.); Penney, Camilla (University of Canterbury); Adams, Keith (Brunel University London); Kijewski-Correa, Tracy (University of Notre Dame); Giardina, Giorgia (TU Delft Geo-engineering)","","2023","After an earthquake, a rapid identification of the damaged building stock is crucial to prioritise rescue operations, ensure primary services to the most affected regions and support reconstruction. Whilst in-situ reconnaissance missions provide invaluable data on the intensity and distribution of earthquake-induced structural damage, the process of collecting field observations is often dangerous, expensive, and is usually undertaken a few weeks after the disaster. Spaceborne Synthetic Aperture Radar (SAR) can remotely provide imagery data of wide affected areas, enabling to reach locations that are difficult or dangerous to access with traditional survey methods. Furthermore, SAR-based observations are independent from daylight illumination and clear-weather conditions. Thanks to the recent availability of Very-High Resolution (VHR) SAR satellites, post-disaster imagery data with sub-metre resolution are now available within a few hours after a major earthquake, opening unprecedented opportunities for complementing in-situ operations. The textural analysis of post-earthquake VHR SAR images could be used to identify backscattering signatures that are likely associated with building damage. However, application has been limited by the lack of methods that correlate the textural properties of damaged structures in radar images with building survey data. In this paper, we present a method using textural features derived from VHR SAR post-event images in combination with building survey data to classify earthquake-induced building damage at city block-level. We tested the proposed method within the context of a joint Structural Extreme Event Reconnaissance (StEER), GeoHazards International (GHI) and Earthquake Engineering Field Investigation Team (EEFIT) mission that followed the 2021 Haiti Earthquake. The developed method was applied to the city of Les Cayes, Haiti, using a post-event Capella SAR image acquired on the 16th of August 2021. The outcomes can positively impact future earthquake scenarios, with the potential to improve rapid disaster response and remotely aid post-earthquake reconnaissance missions.","post-disaster reconnaissance; remote sensing; texture analysis","en","conference paper","","","","","","","","","","","Geo-engineering","","",""
"uuid:98afe3ba-fa0d-4834-b802-60c29196ac35","http://resolver.tudelft.nl/uuid:98afe3ba-fa0d-4834-b802-60c29196ac35","Big slopes, little data: data-driven nowcasting of deep-seated landslide deformation","van Natijne, A.L. (TU Delft Optical and Laser Remote Sensing)","Lindenbergh, R.C. (promotor); Bogaard, T.A. (promotor); Delft University of Technology (degree granting institution)","2023","Landslides are a major geohazard in hilly and mountainous environments. We focus on slow-moving, deep-seated landslides that are characterized by gradual, non-catastrophic deformations of millimeters to decimeters per year and cause extensive economic damage. To assess their potential impact and for the design of mitigation solutions, a detailed understanding of the slope processes is desired. Moreover, where landslide hazard mitigation is impossible, early warning systems are a valuable alternative to reduce landslide risk.
Recent studies have demonstrated the effective application of machine learning for deformation forecasting to specific cases of slow-moving, non-catastrophic, deep-seated landslides. Machine learning, combined with satellite remote sensing products offers new opportunities for both local and regional monitoring of areas with unstable slopes and associated processes without costly and logistically challenging inspection of the landslide. To test to what extent data-driven machine learning techniques and remote sensing observations can be used for landslide deformation forecasting, we developed a machine learning based nowcasting model on the multi-sensor monitored, deep-seated Vögelsberg landslide, near Innsbruck, Tyrol, Austria. Our goal was to link the landslide deformation pattern to the conditions on the slope, and to produce a four-day, short-term forecast, a nowcast, of deformation accelerations.
Changes in hillslope hydrology shift the balance between the shear strength of the soil and the shear (sliding) force applied by the gravitational forces acting on the landmass. Therefore, precipitation, snowmelt, soil moisture, evaporation, and air temperature were identified as hydro-meteorological variables with high potential for forecasting deformation dynamics. Time series of those variables were obtained from remote sensing sources where possible, and otherwise from reanalysis sources as surrogate for data that is likely to be available in the near future. Deformation, the result of slope instability, was monitored daily by a local, automated total station.
Interferometric Synthetic Aperture Radar (InSAR) has shown to be a valuable resource of deformation information from space. However, due to the complex interaction with topography in mountainous environments, its potential is often questioned. We showed that 91% of the world’s slopes are observable by InSAR, given the presence of a coherent scatterer, i.e. a natural or man-made object that exhibits consistent radar reflection over time. A global map is provided to indicate the sensitivity of InSAR to assess downslope deformation on any particular slope. To quickly assess the presence of coherent scatterers, before further investigation, we developed an application in Google Earth Engine to estimate the presence and location of coherent scatterers on a slope. However, the current accuracy and temporal resolution of Sentinel-1 SAR acquisitions proved insufficient to identify the acceleration phases at Vögelsberg.
The five years of daily deformation and hydro-meteorological observations at the Vögelsberg landslide is quite limited for a machine learning model. Therefore, a nowcasting model of low complexity was required. To limit the number of parameters to be optimized, the model was designed to mimic a bucket model, a simple hydrological model. A shallow neural network based on long short-term memory, was implemented in TensorFlow, as custom sequence of existing building blocks. Furthermore, a traditional neural network and recurrent neural network were tested for comparison. Thanks to the limited complexity of the model, the major contributors could be determined by trial-and-error of nearly 150 000 model variations.
Models including soil moisture information are more likely to generate high quality nowcasts, followed by models based solely on precipitation or snowmelt. Although none of the shallow neural network configurations produced a convincing nowcast deformation, they provide important context for future attempts. The machine learning model was poorly constrained as only five years of observations were available in combination with the four acceleration events that occurred in these five years. Furthermore, standard error metrics, like mean squared error, are unsuitable for model optimization for landslide nowcasting.
We showed that landslide deformation nowcasting is not a straightforward application of machine learning. The complexity of the machine learning model formulation at the Vögelsberg illustrates the necessity of expert judgement in the design and evaluation of a data-driven nowcast of slowly deforming slopes. Furthermore, to prepare for unexpected modelling developments, a high level of project level data organisation is recommended. There is a long road ahead for the large scale implementation of machine learning in landslide nowcasting and Early Warning Systems. However, a future, successful nowcasting system will require a simple, robust model and frequent, high quality and event-rich data to train upon.","Deep-seated landslide; Machine learning; Remote sensing; Early warning systems; InSAR","en","doctoral thesis","","978-94-6384-442-0","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:f3def408-0808-4f86-81a9-479d96d7914c","http://resolver.tudelft.nl/uuid:f3def408-0808-4f86-81a9-479d96d7914c","Flood susceptibility mapping using multi-temporal SAR imagery and novel integration of nature-inspired algorithms into support vector regression","Mehravar, Soroosh (University of Tehran); Razavi-Termeh, Seyed Vahid (Sejong University); Moghimi, Armin (K.N. Toosi University of Technology; Leibniz Universität); Ranjgar, Babak (K.N. Toosi University of Technology); Foroughnia, Fatemeh (TU Delft Geo-engineering); Amani, Meisam (Wood Environment and Infrastructure Solutions)","","2023","Flood has long been known as one of the most catastrophic natural hazards worldwide. Mapping flood-prone areas is an important part of flood disaster management. In this study, a flood susceptibility mapping framework was developed based on a novel integration of nature-inspired algorithms into support vector regression (SVR). To this end, various remote sensing (RS) and geographic information system (GIS) datasets were applied to the hybridized SVR models to map flood susceptibility in Ahwaz township, Iran. The proposed framework has two main steps: 1) updating the flood inventory (historical flooded locations) using the proposed RS-based flood detection method developed within the google earth engine (GEE) platform. The mosaicked images of multi-temporal Sentinel-1 synthetic aperture radar (SAR) data have been used in this step; 2) producing flood susceptibility map using the standalone SVR and hybridized model of SVR. The hybridized methods were derived from a novel integration of SVR with meta-heuristic algorithms, hence forming the SVR-bat algorithm (SVR-BA), SVR-invasive weed optimization (SVR-IWO), and SVR-firefly algorithm (SVR-FA). A spatial database of flood locations and 11 conditioning factors (altitude, slope angle, aspect, topographic wetness index, stream power index, normalized difference vegetation index (NDVI), distance to stream, curvature, rainfall, soil type, and land use/cover) were built for the susceptibility modelling. The accuracy of the proposed model was evaluated using the statistical and sensitivity indices, such as root mean square error (RMSE), receiver operating characteristic (ROC) and area under the ROC curve (AUROC) index. The results indicated that all hybridized models outperformed the standalone SVR. According to AUROC values, the predictive power of the SVR-FA was the highest with the value of 0.81, followed by SVR-IWO, SVR-BA, and SVR with values of 0.80, 0.79, and 0.77, respectively.","Flood susceptibility mapping; Nature-inspired algorithms; Remote sensing; SAR imagery; Support vector regression (SVR)","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:ef628c1d-65ee-4023-96aa-a1a76b4625f8","http://resolver.tudelft.nl/uuid:ef628c1d-65ee-4023-96aa-a1a76b4625f8","A New Framework of 17 Hydrological Ecosystem Services (HESS17) for Supporting River Basin Planning and Environmental Monitoring","Hà, T.L. (TU Delft Water Resources; Institute of Water Resources Planning); Bastiaanssen, W.G.M. (TU Delft Water Resources; IrriWatch); Simons, Gijs W. H. (FutureWater -Wageningen); Poortinga, Ate (SERVIR-Mekong; Spatial Informatics Group)","","2023","Hydrological ecosystem services (HESS) describe the benefits of water for multiple purposes with an emphasis on environmental values. The value of HESS is often not realized because primary benefits (e.g., food production, water withdrawals) get the most attention. Secondary benefits such as water storage, purification or midday temperature cooling are often overlooked. This results in an incorrect evaluation of beneficial water usage in urban and rural resettlements and misunderstandings when land use changes are introduced. The objective of this paper is to propose a standard list of 17 HESS indicators that are in line with the policy and philosophy of the Consultative Group of International Agricultural Research (CGIAR) and that are measurable with earth observation technologies in conjunction with GIS and hydrological models. The HESS17 framework considered indicators that can be directly related to water flows, water fluxes and water stocks; they have a natural characteristic with minimal anthropogenic influence and must be quantifiable by means of earth observation models in combination with GIS and hydrological models. The introduction of a HESS framework is less meaningful without proper quantification procedures in place. Because of the widely diverging management options, the role of water should be categorized as (i) consumptive use (i.e., evapotranspiration and dry matter production) and (ii) non-consumptive use (stream flow, recharge, water storage). Governments and responsible agencies for integrated water management should recognize the need to include HESS17 in water allocation policies, water foot-printing, water accounting, transboundary water management, food security purposes and spatial land-use planning processes. The proposed HESS17 framework and associated methods can be used to evaluate land, soil and water conservation programs. This paper presents a framework that is non-exhaustive but can be realistically computed and applicable across spatial scales.","hydrological ecosystemservices; remote sensing; ecosystem services framework; ecosystem services accounting","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:3fb1e828-c2de-462b-b2ca-2cba96ca2568","http://resolver.tudelft.nl/uuid:3fb1e828-c2de-462b-b2ca-2cba96ca2568","Determination of Spatially-Distributed Hydrological Ecosystem Services (HESS) in the Red River Delta Using a Calibrated SWAT Model","Hà, T.L. (TU Delft Water Resources; Institute of Water Resources Planning); Bastiaanssen, W.G.M. (TU Delft Water Resources; IrriWatch)","","2023","The principles of Integrated Water Resources Management (IWRM), conservation of natural capital, and water accounting requires Hydrological Eco-System Services (HESS) to be determined. This paper presents a modeling approach for quantifying the HESS framework using the Soil Water Assessment Tool (SWAT). SWAT was used–after calibration against remote sensing data–to quantify and spatially identify total runoff, natural livestock feed production, fuelwood from natural forests, dry season flow, groundwater recharge, root zone storage for carrying over water from wet to dry season, sustaining rainfall, peak flow attenuation, carbon sequestration, microclimate cooling, and meeting environmental flow requirements. The environmental value of the current land use and vegetation was made explicit by carrying out parallel simulations for bare soil and vegetation conditions and reporting the incremental ecosystem services. Geographical areas with more and fewer HESS are identified. The spatial and temporal variability of annual HESS services is demonstrated for the Day Basin—which is part of the Red River delta (Vietnam)—for the period 2003 to 2013. The result shows that even though the basin is abundant with HESS, e.g., 7482 m3/ha of runoff, 3820 m3/ha of groundwater recharge, the trend for many HESS values, e.g., micro-climate cooling, meeting environmental flow requirements, and rootzone storage, are declining. It is found and proven that quantified HESS indicators highlighted the provisioning and regulating characters of ecosystem services, as well as geographical hotspots across the basin. The SWAT model shows the capability of simulating terrestrial eco-hydrological processes such as climate, soil, and current land use. The methodology illustrates how eco-hydrologists can benchmark ecosystem values and include HESS in exploring river basin management scenarios, climate change studies, and land use planning.","hydrological ecosystem services; hydrological modeling; remote sensing; ecosystem service accounting; SWAT; Red River Basin","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:631ddc7f-e8c3-4616-b433-1cc0a1cf2ce4","http://resolver.tudelft.nl/uuid:631ddc7f-e8c3-4616-b433-1cc0a1cf2ce4","Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020","Otosaka, I.N. (University of Leeds); Shepherd, Andrew (University of Leeds); Ivins, Erik R. (California Institute of Technology); Schlegel, Nicole-Jeanne (California Institute of Technology); Amory, Charles (Université Grenoble Alpes); Simon, K.M. (TU Delft Physical and Space Geodesy); Schrama, Ernst (TU Delft Astrodynamics & Space Missions); van der Wal, W. (TU Delft Astrodynamics & Space Missions); Wouters, B. (TU Delft Physical and Space Geodesy; Universiteit Utrecht)","","2023","Ice losses from the Greenland and Antarctic ice sheets have accelerated since the 1990s, accounting for a significant increase in the global mean sea level. Here, we present a new 29-year record of ice sheet mass balance from 1992 to 2020 from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE). We compare and combine 50 independent estimates of ice sheet mass balance derived from satellite observations of temporal changes in ice sheet flow, in ice sheet volume, and in Earth's gravity field. Between 1992 and 2020, the ice sheets contributed 21.0±1.9g€¯mm to global mean sea level, with the rate of mass loss rising from 105g€¯Gtg€¯yr-1 between 1992 and 1996 to 372g€¯Gtg€¯yr-1 between 2016 and 2020. In Greenland, the rate of mass loss is 169±9g€¯Gtg€¯yr-1 between 1992 and 2020, but there are large inter-annual variations in mass balance, with mass loss ranging from 86g€¯Gtg€¯yr-1 in 2017 to 444g€¯Gtg€¯yr-1 in 2019 due to large variability in surface mass balance. In Antarctica, ice losses continue to be dominated by mass loss from West Antarctica (82±9g€¯Gtg€¯yr-1) and, to a lesser extent, from the Antarctic Peninsula (13±5g€¯Gtg€¯yr-1). East Antarctica remains close to a state of balance, with a small gain of 3±15g€¯Gtg€¯yr-1, but is the most uncertain component of Antarctica's mass balance. The dataset is publicly available at 10.5285/77B64C55-7166-4A06-9DEF-2E400398E452 (IMBIE Team, 2021).","Antarctica; Greenland; ice sheet; remote sensing; sea level","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:53904f8f-999d-45e3-94ab-6176a3b07eda","http://resolver.tudelft.nl/uuid:53904f8f-999d-45e3-94ab-6176a3b07eda","Applicability of the Global Land Evaporation Amsterdam Model Data for Basin-Scale Spatiotemporal Drought Assessment","Khoshnazar, Ali (IHE Delft Institute for Water Education); Corzo Perez, Gerald A. (IHE Delft Institute for Water Education); Diaz, Vitali (TU Delft Water Resources)","Singh, Vijay P. (editor); Yadav, Shalini (editor); Yadav, Krishna Kumar (editor); Corzo Perez, Gerald Augusto (editor); Muñoz-Arriola, Francisco (editor); Yadava, Ram Narayan (editor)","2023","Drought directly impacts the living organisms and environment, and thereby, its assessment is essential. Different drought indices require different data, which can be obtained based on models or in-situ measurements, demanding a significant amount of effort. Using remotely sensed (RS) data from satellites can facilitate this data acquisition. Nowadays, more and more satellite techniques are rising, highlighting the need to assess the accuracy of their data and the reliability of the results obtained by employing them. The Wet-environment Evapotranspiration Precipitation Standardized Index (WEPSI) has shown good performance in drought monitoring and assessment, especially for agricultural purposes. This chapter employs the Global Land Evaporation Amsterdam Model (GLEAM) data to investigate its applicability in the Lempa River basin drought assessment using WEPSI. In this order, evaluated data obtained from the Water Evaluation and Planning system (WEAP) were used as the basis for comparison. Precisely, a comparison was made with GLEAM and WEAP-based data as well as WEPSI time series based on these two datasets. The results show a relatively high similarity between these two datasets and calculated WEPSI drought indices. This validates the good performance of GLEAM-based data in drought monitoring and assessment based on WEPSI.","Remote sensing; GLEAM; Drought index; WEPSI; Drought assessment; Drought monitoring; Drought analysis; Agricultural drought; WEAP; Lempa River basin","en","book chapter","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-02","","","Water Resources","","",""
"uuid:640cbd21-caab-400f-a80f-09f9aef09181","http://resolver.tudelft.nl/uuid:640cbd21-caab-400f-a80f-09f9aef09181","Contrail Altitude Estimation Based on Shadows Detected in Landsat Imagery","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2023","Contrails contribute to global warming by trapping outgoing terrestrial radiation, exerting an immediate warming influence on the climate. The climatic impact of contrails is potentially comparable to that of aviation’s carbon emissions. This underlines the importance of minimizing contrail formation to mitigate the climate effects of aviation, both now and in the future. The evaluation of contrails demands more precise data on the location and altitude where they form. Remote sensing imagery enables the identification of their location. Nevertheless, determining the altitude of the contrail remains problematic, complicating the identification of the source flight. This study introduces a novel method that enables researchers to determine the altitude of a contrail solely using Landsat data by analysing shadows cast by contrails. Through validation against ADS-B data from OpenSky, we demonstrate that such a technique can achieve the accuracy of a few hundreds of meters, which is suitable for incorporation into a climate-optimized routing system. Finally, a ResUNet segmentation model is also presented, which can identify contrails and their shadows in Landsat imagery. These results constitute a step forward for more accurate contrail dataset and models.","Sustainability; Contrails; Remote Sensing; Atmospheric Science; OpenSky; Aircraft Surveillance Data","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:5f1280f0-2190-493c-a057-3611b0bb3058","http://resolver.tudelft.nl/uuid:5f1280f0-2190-493c-a057-3611b0bb3058","Three-Dimensional Mapping of Habitats Using Remote-Sensing Data and Machine-Learning Algorithms","Amani, Meisam (Henan Polytechnic University; WSP Global Inc.); Foroughnia, Fatemeh (TU Delft Geo-engineering); Moghimi, Armin (Leibniz University Hannover); Mahdavi, Sahel (WSP Global Inc.); Jin, Shuanggen (Chinese Academy of Sciences; Henan Polytechnic University)","","2023","Progress toward habitat protection goals can effectively be performed using satellite imagery and machine-learning (ML) models at various spatial and temporal scales. In this regard, habitat types and landscape structures can be discriminated against using remote-sensing (RS) datasets. However, most existing research in three-dimensional (3D) habitat mapping primarily relies on same/cross-sensor features like features derived from multibeam Light Detection And Ranging (LiDAR), hydrographic LiDAR, and aerial images, often overlooking the potential benefits of considering multi-sensor data integration. To address this gap, this study introduced a novel approach to creating 3D habitat maps by using high-resolution multispectral images and a LiDAR-derived Digital Surface Model (DSM) coupled with an object-based Random Forest (RF) algorithm. LiDAR-derived products were also used to improve the accuracy of the habitat classification, especially for the habitat classes with similar spectral characteristics but different heights. Two study areas in the United Kingdom (UK) were chosen to explore the accuracy of the developed models. The overall accuracies for the two mentioned study areas were high (91% and 82%), which is indicative of the high potential of the developed RS method for 3D habitat mapping. Overall, it was observed that a combination of high-resolution multispectral imagery and LiDAR data could help the separation of different habitat types and provide reliable 3D information.","habitat mapping; remote sensing; satellite imagery; LiDAR; 3D mapping","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:10b4e1ea-9420-4e98-8cf6-fa75fdd9ed9d","http://resolver.tudelft.nl/uuid:10b4e1ea-9420-4e98-8cf6-fa75fdd9ed9d","A data-driven high spatial resolution model of biomass accumulation and crop yield: Application to a fragmented desert-oasis agroecosystem","Chen, Qiting (Chinese Academy of Sciences); Jia, Li (Chinese Academy of Sciences); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Hu, Guangcheng (Chinese Academy of Sciences); Wang, Kun (Chinese Academy of Sciences); Yi, Zhiwei (Chinese Academy of Sciences); Zhou, Jie (Central China Normal University); Peng, Fei (Chinese Academy of Sciences, Lanzhou); Ma, Shaoxiu (Chinese Academy of Sciences, Lanzhou)","","2023","Information on crop yield is important for food security, in particular under the conditions of climate change and growing population worldwide. We developed a new fully distributed, high spatial resolution, model of biomass accumulation and crop yield applicable to a highly heterogeneous desert-oasis agroecosystem. The bulk of required input data is obtained by retrieving pixel-wise biogeophysical variables from a suite of very diverse satellite data. Both temperature and water stress conditions at field-scale are given full consideration, while the model was designed to strike a balance between model applicability and satisfactory characterization of the heterogeneous desert-oasis system to estimate field-scale yield. The development of this model relies on three main innovations. First, the start and end of the growing season were estimated for each pixel by calibrating the high spatial and temporal resolution observations of Normalized Difference Vegetation Index (NDVI) by Sentinal-2 (S2) MSI (Multi-Spectral Instrument) against limited local phenological information. Second, to monitor crop water stress, account taken of irrigation, a process-based water and energy balance model was applied to estimate the actual evapotranspiration (ET). This requires knowledge of soil water availability, which is characterized by downscaling the ASCAT (Advanced SCATterrometer) soil moisture data product. To capture the dominant features of the eco-hydrological conditions in the desert and oasis agroecosystem, ET was further downscaled from the 1 km resolution. Third, likewise the water stress indicator, the air temperature stress indicator was mapped after characterizing the thermal contrast and heterogeneity of the desert-oasis system, by generating time series of air temperature at 1 km spatial resolution using the MODIS (Moderate Resolution Imaging Spectroradiometer) Land Surface Temperature (LST) data product. In the temporal dimension, gaps were mitigated by applying time series analysis techniques to reconstruct cloud-free time series of LST, NDVI, fAPAR and albedo. These innovations add up to a high resolution characterization of crop response to the geospatial variability of weather and climate forcing in the desert-oasis agroecosystem. The model was applied to the dominant crops, i.e., spring wheat, maize, sunflower, and melon, in the oases of the Shiyang River Basin (northwestern China) characterized by a rather fragmented land use. The high resolution of pixel-wise ecohydrological parameters, i.e., crop phenology, temperature stress and water stress factors successfully reflect differences of crops with different phenology and location in the oases. The relative errors for wheat and maize yields compared to the census data are less than 5% at district level. At the county level, the relative errors of wheat yields of Liangzhou, Minqin, Gulang, Jinchuan, and Yongchang equal to 0.87%, 24.2%, 9.7%, 12.5%, and 7.2%. For maize, the dominant crop, the error on estimated yields was less than 5%, except in Gulang. The relative error on estimated yield for sunflower was less than 10% compared to agricultural census data. The relative error on estimated melon yield was 16%. This performance highlights the applicability of the model to estimate field-scale yields in agroecosystems characterized by fragmented land use.","Crop yield estimation; Heterogeneous agroecosystem; High resolution; Multi-source remote sensing data","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:43bc5020-1406-432c-bd2e-32c99d156c53","http://resolver.tudelft.nl/uuid:43bc5020-1406-432c-bd2e-32c99d156c53","A scalable software package for time series reconstruction of remote sensing datasets on the Google Earth Engine platform","Zhou, J. (TU Delft Optical and Laser Remote Sensing; Central China Normal University); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Jia, Li (Chinese Academy of Sciences); Gao, Bo (Capital Normal University); Zhao, Feng (Central China Normal University); Cui, Yilin (Central China Normal University); Xiong, Xuqian (Central China Normal University); Liu, Xuan (Central China Normal University); Li, Dengchao (The First Geological brigade of Hubei Geological Bureau)","","2023","Spatiotemporal residual noise in terrestrial earth observation products, often caused by unfavorable atmospheric conditions, impedes their broad applications. Most users prefer to use gap-filled remote sensing products with time series reconstruction (TSR) algorithms. Applying currently available implementations of TSR to large-volume datasets is time-consuming and challenging for non-professional users with limited computation or storage resources. This study introduces a new open-source software package entitled ‘HANTS-GEE’ that implements a well-known and robust TSR algorithm, i.e. Harmonic ANalysis of Time Series (HANTS), on the Google Earth Engine (GEE) platform for scalable reconstruction of terrestrial earth observation data. Reconstruction tasks can be conducted on user-defined spatiotemporal extents when raw datasets are available on GEE. According to site-based and regional-based case evaluation, the new tool can effectively eliminate cloud contamination in the time series of earth observation data. Compared with traditional PC-based HANTS implementation, the HANTS-GEE provides quite consistent reconstruction results for most terrestrial vegetated sites. The HANTS-GEE can provide scalable reconstruction services with accelerated processing speed and reduced internet data transmission volume, promoting algorithm usage by much broader user communities. To our knowledge, the software package is the first tool to support full-stack TSR processing for popular open-access satellite sensors on cloud platforms.","gap-filling; Google Earth Engine; HANTS; remote sensing; Time series reconstruction","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:e5574961-323c-4d31-92a3-8b01d6edb320","http://resolver.tudelft.nl/uuid:e5574961-323c-4d31-92a3-8b01d6edb320","Assessing impacts of climate variability and land use/land cover change on the water balance components in the Sahel using Earth observations and hydrological modelling","Bennour, Ali (Chinese Academy of Sciences; University of Chinese Academy of Sciences; Commissariat Regional au Development Agricole); Jia, Li (Chinese Academy of Sciences); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Zheng, Chaolei (Chinese Academy of Sciences); Zeng, Yelong (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Barnieh, Beatrice Asenso (Chinese Academy of Sciences; University of Energy and Natural Resources); Jiang, Min (Chinese Academy of Sciences)","","2023","Study region: Senegal river (SRB), Niger river (NRB), and Lake Chad basins (LCB). Study focus: We investigated the impacts of land use/land cover change (LULC) and climate variability on the water balance components from 1990 to 2020. We applied the Soil and Water Assessment Tool (SWAT) coupled with remote sensing retrievals of actual evapotranspiration (ETa) and surface soil moisture (SSM). To separate the impacts of the two aforementioned factors, two numerical experiments were designed: (i) climate variability effects by applying frozen LULC while changing the climate; (ii) LULC change impacts by applying frozen climate while changing LULC. New hydrological insights for the region: Overall, at the basin level, the results indicated that climate variability had the dominant role in increasing groundwater recharge, surface runoff, groundwater return flow and lateral flow in LCB and SRB. These increases triggered the recovery of lake area and higher water table in LCB and increased in SRB streamflow, while water scarcity increased in NRB. In contrast, the separate effect of LULC change, specifically natural vegetation expansion, increased actual ET and decreased the surface runoff, which could be a reason for lake area depletion in LCB and decreasing SRB and NRB streamflow. At the sub-basin level, LULC change, i.e. a gain in cropland and urban areas at the expense of forests in some sub-basins in NRB, led to a local increase in surface runoff. This implies a better redistribution of water in downstream and compensates the deficit in surface runoff caused by natural vegetation expansion in some other catchments. These changes, simultaneously with high intensity and long-duration precipitation, may increase the likelihood of inundation in some small catchments in the Niger river basin. These outcomes give useful hydrological insights into water and land management by emphasizing the crucial role of water recycling.","African Sahel; Climate variability; ETMonitor; LULC change; Remote sensing; Soil moisture; SWAT model","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:c53cf5a9-dc1a-4799-851e-456de6f9e1c3","http://resolver.tudelft.nl/uuid:c53cf5a9-dc1a-4799-851e-456de6f9e1c3","Remote Sensed and/or Global Datasets for Distributed Hydrological Modelling: A Review","Ali, M.H. (TU Delft Water Resources; IHE Delft Institute for Water Education); Popescu, Ioana (IHE Delft Institute for Water Education); Jonoski, Andreja (IHE Delft Institute for Water Education); Solomatine, D.P. (TU Delft Water Resources; IHE Delft Institute for Water Education)","","2023","This research paper presents a systematic literature review on the use of remotely sensed and/or global datasets in distributed hydrological modelling. The study aims to investigate the most commonly used datasets in hydrological models and their performance across different geographical scales of catchments, including the micro-scale (<10 km2), meso-scale (10 km2–1000 km2), and macro-scale (>1000 km2). The analysis included a search for the relation between the use of these datasets to different regions and the geographical scale at which they are most widely used. Additionally, co-authorship analysis was performed on the articles to identify the collaboration patterns among researchers. The study further categorized the analysis based on the type of datasets, including rainfall, digital elevation model, land use, soil distribution, leaf area index, snow-covered area, evapotranspiration, soil moisture and temperature. The research concluded by identifying knowledge gaps in the use of each data type at different scales and highlighted the varying performance of datasets across different locations. The findings underscore the importance of selecting the right datasets, which has a significant impact on the accuracy of hydrological models. This study provides valuable insights into the use of remote sensed and/or global datasets in hydrological modelling, and the identified knowledge gaps can inform future research directions.","distributed hydrological modelling; global datasets; remote sensing","en","review","","","","","","","","","","","Water Resources","","",""
"uuid:4388fcd3-466b-4bde-a261-40b56ef8e6c4","http://resolver.tudelft.nl/uuid:4388fcd3-466b-4bde-a261-40b56ef8e6c4","Open-access remote sensing data for cooperation in transboundary water management","Yalew, S. G. (IHE Delft Institute for Water Education); van der Zaag, P. (TU Delft Water Resources; IHE Delft Institute for Water Education); Tran, N.B. (TU Delft Water Resources; IHE Delft Institute for Water Education); Michailovsky, C. I.B. (IHE Delft Institute for Water Education); Salvadore, E. (IHE Delft Institute for Water Education; Vrije Universiteit Brussel); Borgomeo, E. (University of Oxford); Karimi, P. (IHE Delft Institute for Water Education); Pareeth, S. (IHE Delft Institute for Water Education); Seyoum, S. D. (IHE Delft Institute for Water Education); Mul, M. L. (IHE Delft Institute for Water Education)","","2023","Open-access remote sensing products provide data for transboundary water management. This study presents a comprehensive overview of the applications, uncertainties and implications of these remote sensing data products in the context of transboundary water management. Focusing on different stages within the transboundary cooperation continuum, we delineate the potential role and application of remote sensing data at the various stages of this cooperation. Despite the uncertainties and capacity requirements for data acquisition, processing and interpretation, we argue that remote sensing broadens opportunities to monitor, assess, forecast, track or validate compliance in transboundary basins, thereby challenging traditional notions of water data exclusivity.","cooperative water management; Remote sensing; transboundary water management; water conflict; water data sharing","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-04-17","","","Water Resources","","",""
"uuid:ed997758-c6bc-48a0-86ad-454094be862b","http://resolver.tudelft.nl/uuid:ed997758-c6bc-48a0-86ad-454094be862b","Systematic errors observed in CryoSat-2 elevation swaths on mountain glaciers and their implications","Haacker, J.M. (TU Delft Physical and Space Geodesy); Wouters, B. (TU Delft Physical and Space Geodesy); Slobbe, D.C. (TU Delft Physical and Space Geodesy)","","2023","Our awareness of ice caps’ and mountain glaciers’ sensitivity to climate change has driven major advances in the application of remote sensing techniques during the past decade. Regarding ESA’s SARIn altimeter CryoSat-2, processing the full waveform to generate swaths of elevation estimates has become standard practice in regions of complex topographies. This technique provides information on areas where we would be blind otherwise. In this article, we discuss systematic errors and analyze their impact on surface elevation measurements and change rates of two test areas. In particular, we focus on periodically occurring errors in elevation swaths, caused by the superposition of coherent signals from range-ambiguous surfaces. They can lead to measurement errors in excess of 10m, affect most measurements in mountainous regions, are difficult to exclude with established post-processing techniques, and occur repeatedly for satellite revisits introducing a 369-day periodicity—difficult to distinguish from the annual cycle. We show a correlation between derived elevation swaths and the sensor view angle and explore the influence of common data exclusion choices on higher-level products. Our results indicate that these systematic errors hold a substantial share of the error budget and that the choice of thresholds impacts higher-level products. We conclude that error correlations need to be considered to characterize the data accuracy. With the established data editing strategies, systematic errors prevent resolving seasonal mass changes of single mountain glacier basins and impact aggregates over larger areas or longer periods.","Coherence; CryoSat-2; error; Ice; mountain glacier; Remote sensing; resolution; Rough surfaces; Spatial resolution; Surface roughness; Surface topography; swath; Systematics; uncertainty","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:9ea72dd0-f5bd-454e-8d40-3db386a148bd","http://resolver.tudelft.nl/uuid:9ea72dd0-f5bd-454e-8d40-3db386a148bd","Contrail minimization through altitude diversions: A feasibility study leveraging global data","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2023","As global flight volume rises, the aviation industry is facing increasing climate challenges. One major factor is the impact of contrails, which trap outgoing terrestrial radiation and counteract emission reduction benefits from emission-optimized flight routes. Our study quantifies contrail-forming flights globally and assesses altitude adjustments necessary to avoid these regions. Using the Integrated Global Radiosonde Archive and global flight data from 2021-2022, we highlight several contrail-prone regions with high air traffic volumes and high potential for contrail-formation. We propose an operational strategy in altitude diversion, which can halve the amount of persistent contrails. Further, we analyse the additional carbon emissions caused by the altitude diversions and safety risks in terms of potential new conflicts. Our findings provide actionable strategies for policymakers to balance climate mitigation and operational challenges in aviation.","Aircraft surveillance data; Atmospheric science; Contrails; OpenSky; Remote sensing; Sustainability","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:43cfb87d-75a9-40a5-9917-448d45d8c613","http://resolver.tudelft.nl/uuid:43cfb87d-75a9-40a5-9917-448d45d8c613","Bridging the data gap: using remote sensing and open-access data for assessing sustainable groundwater use in Kumasi, Ghana","Potter, Estela Fernandes (Student TU Delft); Monney, Isaac (Akenten Appiah-Menka University of Skills Training and Entrepreneurial Development); Rutten, M.M. (TU Delft Water Resources)","","2023","Groundwater use has significantly increased in the rapidly urbanising city of Kumasi, Ghana. But there is a lack of understanding of whether the groundwater system can sustain the growing demand in the future amidst climate change and rapid urbanisation. Using remote sensing datasets and a water balance approach, this study estimated the groundwater recharge and assessed how urbanisation has affected its groundwater sustainability. Sustainability is investigated by comparing multi-annual groundwater withdrawals to long-term average annual replenishment. Results show that while groundwater recharge has decreased by 80% from 1986 to 2020, mainly due to substantial (63%) loss of permeable land, groundwater consumption has seen a six-fold increase. Groundwater consumption in 2020 exceeded the long-term average groundwater recharge by 2.2Mm3, suggesting that the current groundwater use trends are unsustainable for future ground-water availability. Under a ‘business-as-usual’ scenario, a four-fold increase in groundwater consumption is predicted by 2050 while climate change and land-cover changes may reduce groundwater recharge by 10% and 55% respectively. Practical measures such as promoting artificial groundwater replenishment approaches, adopting low-impact development and instituting demand management measures must be implemented in the Metropolis. This should be informed by further studies to ascertain the exact condition of the groundwater.","groundwater; Kumasi; remote sensing; sustainability; urbanisation; water consumption","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:b0a752b0-7cd5-41a2-861a-4c51434582a5","http://resolver.tudelft.nl/uuid:b0a752b0-7cd5-41a2-861a-4c51434582a5","A high-resolution record of surface melt on Antarctic ice shelves using multi-source remote sensing data and deep learning","de Roda Husman, S. (TU Delft Physical and Space Geodesy); Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning; Katholieke Universiteit Leuven); Bolibar, J. (TU Delft Physical and Space Geodesy); Izeboud, M. (TU Delft Mathematical Geodesy and Positioning); Hu, Zhongyang (Universiteit Utrecht); Shukla, S. (TU Delft Physical and Space Geodesy); van der Meer, Marijn (ETH Zürich); Long, David (Brigham Young University); Wouters, B. (TU Delft Physical and Space Geodesy)","","2023","While the influence of surface melt on Antarctic ice shelf stability can be large, the duration and affected area of melt events are often small. Therefore, melt events are difficult to capture with remote sensing, as satellite sensors always face the trade-off between spatial and temporal resolution. To overcome this limitation, we developed UMelt: a surface melt record for all Antarctic ice shelves with a high spatial (500 m) and high temporal (12 h) resolution for the period 2016–2021. Our approach is based on a deep learning model, specifically a U-Net, which was developed in Google Earth Engine. The U-Net combines microwave remote sensing observations from three sources: Sentinel-1, Special Sensor Microwave Imager/Sounder (SSMIS), and Advanced Scatterometer (ASCAT). The U-Net was trained on the Shackleton Ice Shelf for melt seasons 2017–2021, using the fine-scale melt patterns of Sentinel-1 as reference data and SSMIS, ASCAT, a digital elevation model, and multi-year Sentinel-1 melt fraction as predictors. The trained U-Net performed well on the Shackelton Ice Shelf for test melt season 2016–2017 (accuracy: 91.3%; F1-score: 86.9%), and the Larsen C Ice Shelf, which was not considered during training (accuracy: 91.0%; F1-score: 89.3%). Using the trained U-Net model, we have successfully developed the UMelt record. UMelt allows Antarctic-wide surface melt to be detected at a small scale while preserving a high temporal resolution, which could lead to new insights into the response of ice shelves to a changing atmospheric forcing.","Antarctica; Enhanced resolution; Google Earth Engine; Machine learning; Microwave remote sensing; Surface melt; U-Net","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:863f7cb6-4d89-4ec7-843a-b8c189dbb005","http://resolver.tudelft.nl/uuid:863f7cb6-4d89-4ec7-843a-b8c189dbb005","Analyzing the Impact of Evolving Combustion Conditions on the Composition of Wildfire Emissions Using Satellite Data","Anderson, Lindsey D. (University of Colorado); Dix, Barbara (University of Colorado); Schnell, Jordan (University of Colorado; National Oceanic and Atmospheric Administration); Yokelson, Robert (University of Montana); Veefkind, j. Pepijn (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); Ahmadov, Ravan (National Oceanic and Atmospheric Administration); de Gouw, Joost (University of Colorado)","","2023","Wildfires have become larger and more frequent because of climate change, increasing their impact on air pollution. Air quality forecasts and climate models do not currently account for changes in the composition of wildfire emissions during the commonly observed progression from more flaming to smoldering combustion. Laboratory measurements have consistently shown decreased nitrogen dioxide (NO2) relative to carbon monoxide (CO) over time, as they transitioned from more flaming to smoldering combustion, while formaldehyde (HCHO) relative to CO remained constant. Here, we show how daily ratios between column densities of NO2 versus those of CO and HCHO versus CO from the Tropospheric Monitoring Instrument (TROPOMI) changed for large wildfires in the Western United States. TROPOMI-derived emission ratios were lower than those from the laboratory. We discuss reasons for the discrepancies, including how representative laboratory burns are of wildfires, the effect of aerosols on trace gas retrievals, and atmospheric chemistry in smoke plumes.","air quality; biomass burning emissions; remote sensing","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:49c64436-d56a-4f2f-8025-efce4aac7ed1","http://resolver.tudelft.nl/uuid:49c64436-d56a-4f2f-8025-efce4aac7ed1","Combining remote sensing techniques and field surveys for post-earthquake reconnaissance missions","Giardina, Giorgia (TU Delft Geo-engineering); Macchiarulo, V. (TU Delft Geo-engineering); Foroughnia, Fatemeh (TU Delft Geo-engineering); Jones, Joshua N. (AECOM Technology Corporation, United Kingdom); Whitworth, Michael R.Z. (AECOM Technology Corporation, United Kingdom); Voelker, Brandon (University of Houston); Milillo, Pietro (University of Houston; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)); Penney, Camilla (University of Canterbury); Adams, Keith (Brunel University); Kijewski-Correa, Tracy (University of Notre Dame)","","2023","Remote reconnaissance missions are promising solutions for the assessment of earthquake-induced structural damage and cascading geological hazards. Space-borne remote sensing can complement in-field missions when safety and accessibility concerns limit post-earthquake operations on the ground. However, the implementation of remote sensing techniques in post-disaster missions is limited by the lack of methods that combine different techniques and integrate them with field survey data. This paper presents a new approach for rapid post-earthquake building damage assessment and landslide mapping, based on Synthetic Aperture Radar (SAR) data. The proposed texture-based building damage classification approach exploits very high resolution post-earthquake SAR data integrated with building survey data. For landslide mapping, a backscatter intensity-based landslide detection approach, which also includes the separation between landslides and flooded areas, is combined with optical-based manual inventories. The approach was implemented during the joint Structural Extreme Event Reconnaissance, GeoHazards International and Earthquake Engineering Field Investigation Team mission that followed the 2021 Haiti Earthquake and Tropical Cyclone Grace.","Building damage; Haiti; Intensity ratio image; Landslides classification; Remote reconnaissance; Remote sensing; SAR; Texture analysis","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:dc2918a4-fbf8-4723-bacb-e3a984ffcbd7","http://resolver.tudelft.nl/uuid:dc2918a4-fbf8-4723-bacb-e3a984ffcbd7","面 向 城 市 场 景 异 源 多 时 相 点 云 的 自 动 配 准","Yang, Z. (TU Delft Urban Data Science; Tongji University); Ye, Qin (Tongji University); Wang, Xufei (Tongji University); Peters, R.Y. (TU Delft Urban Data Science)","","2023","Objective Recent advancements in laser scanners and photogrammetry technology have significantly reduced the cost of acquiring 3D point clouds. Consequently, various types of point clouds have gradually become popular data sources for urban applications. The accurate registration of cross-source and multi-temporal point clouds must be ensured before developing applications based on 3D point clouds. However, this is a challenging task owing to (1) the large amount of data to be considered, (2) the wide discrepancy in characteristics between cross-source point clouds, and (3) the significant changes in a scene represented by multi-temporal point clouds. These data characteristics can harm the extraction and matching of registration primitives, resulting in the poor performance of marker-free registration techniques. In this paper, we propose an automated, efficient, and marker-free method for registering cross-source and multi-temporal point clouds in urban areas. Methods The proposed registration method comprises three stages: keypoint generation, correspondence matching, and transformation estimation. (1) Keypoint generation. We generate object-level virtual keypoints as registration primitives rather than directly extracting local features from point clouds, which are redundant and sensitive to outliers and missing data. Specifically, the ground points are first filtered out via the cloth simulation filtering algorithm. The remaining points are decomposed into planar segments by fitting planes in a region-growing manner. Finally, virtual keypoints are determined as the endpoints of intersecting line segments of two adjacent planes. (2) Correspondence matching. First, local triangles are constructed using the generated virtual keypoints as vertices to encode the relative spatial relationships among keypoints within a point cloud. Second, the triangle sets of both point clouds are mapped to a feature space where the triangles become 3D feature points. For each feature point in the source point cloud, we determine its closest point in the target point cloud, forming triangle pairs between the two point clouds. Finally, we propose an improved global matching approach with linear time complexity to extract correspondences encoded in the triangle pairs. (3) Transformation estimation. As cross-source and multi-temporal point clouds are typically well-leveled, registration can be achieved by aligning the two point clouds horizontally and translating them vertically. We use the horizontal coordinates of the correspondences to estimate the 2D horizontal transformation and their vertical coordinates to calculate the vertical translation. Results and Discussions We evaluated the effectiveness of the proposed method using large-scale real-world urban point clouds. The experimental data consist of six cross-source and multi-temporal point clouds, including three airborne light detection and ranging (LiDAR) point clouds and three photogrammetric point clouds, which cover an urban area of 1. 8 km2 in Rotterdam, the Netherlands. Each point cloud comprises a large number of points (approximately 20‒60 million points per point cloud; refer to Table 1 for details). Additionally, as the point clouds were collected over a long period of time, many of the objects in the scene have changed considerably. These two characteristics make them suitable for performing comprehensive evaluations of automatic marker-free registration methods. To evaluate the registration results qualitatively, we visualized a randomly selected region (Fig. 7) and three manually selected buildings with varying architectural styles (Fig. 8). Despite the different characteristics of cross-source point clouds and the significant changes in scenes, the proposed method could accurately align all five registration pairs formed by the six experimental point clouds. To evaluate the registration results quantitatively, we calculated both matrix-based errors (i. e., rotation and translation errors) as well as pointwise errors. The evaluation is summarized in Table 4. Our automatic registration results have an average pointwise error of 6.4 cm, whereas the average matrix-based errors are 0.2′for rotation and 7.4 cm for translation. Furthermore, despite the massive size of the experimental point clouds, the proposed approach required only 105.7 s to achieve pairwise registration on average. Both qualitative and quantitative results demonstrate the effectiveness of the proposed method for registering cross-source and multi-temporal urban point clouds. Conclusions A fully automated marker-free registration approach is presented for cross-source and multi-temporal point clouds in urban environments. Object-level virtual keypoints are generated from urban point clouds as registration primitives, thereby overcoming the challenge of identifying valid corresponding features. By encoding rigid body spatial relations among the generated virtual keypoints, we establish correspondences between the source and target point clouds, resulting in efficient matching for large-scale urban scenes. Experiments on real-world data demonstrate that the proposed method can automatically, accurately, and efficiently register cross-source and multi-temporal point clouds in urban areas, indicating its practical utility. In the future, we would like to collect more data to test the robustness of the proposed method. Moreover, we intend to study the potential of the proposed matching algorithm in the fusion of general multi-source data, e. g. , aligning 3D building point clouds with 2D building footprints.","cross-source and multitemporal point clouds; kinematics of rigid bodies; light detection and ranging; photogrammetric point clouds; point cloud registration; remote sensing","zh","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-10-14","","","Urban Data Science","","",""
"uuid:d6d33853-739e-4722-9ece-f104eab27c12","http://resolver.tudelft.nl/uuid:d6d33853-739e-4722-9ece-f104eab27c12","Roadmap on measurement technologies for next generation structural health monitoring systems","Laflamme, Simon (Iowa State University); Ubertini, Filippo (University of Perugia); Di Matteo, Alberto (Università degli Studi di Palermo); Pirrotta, Antonina (Università degli Studi di Palermo); Perry, Marcus (University of Strathclyde); Fu, Yuguang (Nanyang Technological University); Glisic, Branko (Princeton University); Shu, Yening (University of California); Giardina, Giorgia (TU Delft Geo-engineering)","","2023","Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots.","autonomous sensing; distributed sensing; multifunctional materials; remote sensing; SHM; structural health monitoring","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:470fccaf-0068-4468-bf6d-d9a26b1c7a02","http://resolver.tudelft.nl/uuid:470fccaf-0068-4468-bf6d-d9a26b1c7a02","Changes in glacier albedo and the driving factors in the Western Nyainqentanglha Mountains from 2001 to 2020","Ren, Shaoting (Chinese Academy of Sciences); Jia, Li (Chinese Academy of Sciences); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Zhang, Jing (Chinese Academy of Sciences)","","2023","Glacier surface albedo dominates glacier energy balance, thus strongly affecting the glacier mass balance. Glaciers in the Western Nyainqentanglha Mountains (WNM) experienced large mass losses in the past two decades, but long-term changes of glacier albedo and its drivers are less understood. In this study, we retrieved glacier albedo with MODIS reflectance data to characterize the spatiotemporal variability of albedo from 2001 to 2020. Air temperature, rainfall, snowfall and deposition of light-absorbing impurities (LAIs) were evaluated as potential drivers of the observed variability in glacier albedo. The results showed that: (1) the glacier albedo experienced large inter-annual fluctuations, with the mean albedo being 0.552 ± 0.002 and a clear decreasing trend of 0.0443 ± 2 × 10-4 dec-1 in the WNM. The fastest decline was observed in autumn and in the vicinity of the equilibrium line altitude, indicating an extended melt season and an expansion of the ablation region to higher elevation; (2) local meteorology and LAIs deposition are the main drivers of glacier albedo change, but their effects on seasonal albedos are different due to different glacier processes. Both air temperature and the balance between liquid and solid precipitation affect summer and autumn albedos due to glacier ablation. Air temperature is the main driver of spring and winter albedos due to sublimation and metamorphism of snow, while snowfall carried by westerlies has limited influence on these two seasonal albedos due to less snowfall. LAIs mainly affect spring albedo due to high concentration coupled with the southerly wind in spring. These findings highlight the significance of changes in glacier albedo and the key role of local meteorology and LAIs deposition in determining such changes, which play an important role in glaciological and cryosphere processes.","energy balance; glacier albedo; mountain glaciers; remote sensing","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:b30a5dcc-81e6-436b-bdf3-c55155d6d82d","http://resolver.tudelft.nl/uuid:b30a5dcc-81e6-436b-bdf3-c55155d6d82d","Peculiarities and Experience of W-Band Cloud Radar Calibration","Yanovsky, Felix J. (National Aviation University); Pitertsev, Aleksander A. (National Aviation University); Unal, C.M.H. (TU Delft Atmospheric Remote Sensing); Russchenberg, H.W.J. (TU Delft Geoscience and Remote Sensing)","","2023","This paper is devoted to discussing peculiarities of W-band cloud radar calibration. After a brief overview of meteorological radar calibration methods for quantitative information retrieval, we focus on problems and their possible solutions with respect to mm-wave radar calibration. The experimental part of the research is based on multi-instrument measurements performed during several years in the Cabauw experimental meteorological site in the Netherlands. The accumulated data are used for comparison of 94 GHz radar rain measurements with non-radar droplet size distribution measurements, provided by laser disdrometers. Calculations are done taking into account data of other in situ meteorological measurements. A specialized MATLAB software tool for processing such complex data and radar calibration is developed and demonstrated.","data integrity; data processing; electromagnetic scattering; radar measurements; radar remote sensing; sensor fusion; signal processing","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","2024-03-28","","Geoscience and Remote Sensing","Atmospheric Remote Sensing","","",""
"uuid:9dacf50b-ac87-4ed4-9878-d2f1f415ed83","http://resolver.tudelft.nl/uuid:9dacf50b-ac87-4ed4-9878-d2f1f415ed83","Adoptable Coastal Remote Sensing Using Wave-field Observations: Instruments, Techniques and Application","Gawehn, M.A. (TU Delft Coastal Engineering)","Aarninkhof, S.G.J. (promotor); de Vries, S. (promotor); van Dongeren, A.R. (copromotor); Delft University of Technology (degree granting institution)","2022","The aim of this study is to innovate wave-based depth-inversion towards smarter and faster algorithms to be used with various remote sensing instruments for broad community use. Wave-based depth inversion describes a branch of coastal remote sensing, which uses video recordings of a wave-field to derive depths and thereby create digital maps of coastal bathymetries. The technique utilizes the fact that waves react to the underlying bathymetry by changing their length and celerity, respectively getting shorter and slower as the water depth gets shallower. Waves may also change their direction due to refraction. Depth inversion techniques using surface wave patterns can handle clear and turbid waters and thereby a variety of global coastal environments. The idea to use observed wave characteristics as a proxy for the underlying bathymetry already came up during the time of the second world war, when the aim was to acquire bathymetry information for military landing operations. Starting around the 1980’s, the idea received more attention among the coastal engineering community, as increased computational power enabled easier analysis of wave-field recordings through spectral decompositions. Since then, different depth inversion algorithms (DIA) have been developed in pursuit of getting increasingly accurate bathymetry maps. Besides estimating depths, some DIAs also incorporate functionalities to map wave propagation directions and wave celerity, and even near-surface currents from wave-field video. While the video recording instruments resemble the hardware, DIAs resemble the software needed for wavebased coastal remote sensing (WCRS).
Yet, WCRS is a specialistic branch within the coastal engineering and -user community. The technique typically requires a certain amount of user-expertise and it has mostly been applied in research settings. While data can be retrieved on kilometre scale with XBand-radars and cameras, it was historically difficult to scale up WCRS to entire coasts, which was a reason to discontinue its application in the Netherlands. Besides land-based instruments (i.e., XBand-radars, fixed camera stations) in the meantime also airborne UAVs, and space-borne satellites can be used to record a wave field, making WCRS more flexible and scalable. These recording instruments have also become more accessible. Moreover, DIAs – the software required to analyse the wave recordings – can be used interchangeably on data of these different instruments. This means that WCRS becomes potentially attractive to a broad user-community of coastal managers, the industry and the coast guard. However, DIAs still restrict broad usage of WCRS: while an important step has been taken in the open accessibility of DIAs, much is still to be gained in their handling and computational speed. This study aims to improve upon that, by building towards operational, self-adaptive and intelligent algorithms, which can provide maps of depth, near-surface currents and wave hydrodynamics on-the-fly. For this purpose, video data from a variety of instruments (fixed camera station, UAV, XBandradar, satellite) on different spatial scales 𝑂(100 m2,1 km2,10 km2,100 km2) and field-sites around the world (Netherlands, UK, USA, Australia, France) are analysed. Combining rapid processing capabilities with a broad applicability this study forms a stepping stone for a potentially broad WCRS user community. The analyses are presented going from land-based to air-borne to space-borne WCRS. This is done in three stages from (1) applying an operational DIA on XBand radar data, to (2) applying an on-the-fly DIA on camera and UAV data, to finally (3) applying a DIA on temporally sparse satellite data.
First, a DIA named XMFit (X-Band Matlab Fitting) is introduced, which is robust, accurate and fast enough for operational use. This is achieved through an iterative procedure that selects the best result among a series of depth and near-surface current estimates. For this study, video data from XBand-radars are analysed. Focusing on depth estimates, XMFit is validated for two case studies in the Netherlands: (1) the “Sand Engine”, a beach mega nourishment at a uniform open coast, and (2) the tidal inlet of the Dutch Wadden Sea island Ameland, characterizing a more complex coast. Considering both sites, the algorithm performance is characterized by a spatially averaged depth bias of −0.9 m at the Sand Engine (corresponding to an 18 h snapshot of the field site) and a time-varying bias of approximately −2–0 m at the Ameland Inlet (corresponding to a one-year time evolution with varying hydrodynamic conditions). When compared to in-situ depth surveys the accuracy is lower, but the time resolution higher. Dutch in-situ surveys typically occur annually, while depth estimates from the Ameland tidal inlet are produced every 50 min by an operational system using a navigational X-Band radar. It enables to monitor the placement of a 5 Mm3 ebb-tidal delta nourishment – a pilot measure for coastal management. Volumetric changes in the nourishment area over the year 2018, occurring at 7 km distance from the radar, are estimated with an error of 7 %. Depth errors statistically correlate with the direction and magnitude of simultaneous near-surface current estimates. Additional experiments on Sand Engine data demonstrate that depth errors may be significantly reduced using an alternative spectral approach and/or by using a Kalman filter.
Having demonstrated the potential of DIAs for operational application, the next step is to design an algorithm that can self-adapt to video from any field-site and can process it on-the-fly. To do so, a DIA is designed whose code architecture for the first time includes the Dynamic Mode Decomposition (DMD) to reduce the data complexity of wavefield video. The DMD is paired with loss-functions to handle spectral noise, and a novel spectral storage system and Kalman filter to achieve fast converging measurements. The algorithm is showcased for videos from ARGUS stations and drones recorded at fieldsites in the USA, UK, Netherlands, and Australia. The performance with respect to mapping bathymetry is validated using ground truth data. It is demonstrated that merely 32 s of video footage is needed for a first mapping update with average depth errors of 0.9–2.6 m. These further reduce to 0.5–1.4 m as the videos continue and more mapping updates are returned. Simultaneously, coherent maps for wave direction and -celerity are achieved as well as maps of local near-surface currents. The algorithm is capable of mapping the coastal parameters on-the-fly and thereby offers analysis of video feeds, such as from drones or operational camera installations. Hence, the innovative application of analysis techniques like the DMD enables both accurate and unprecedentedly fast coastal reconnaissance.
With a skilled, intelligent DIA at hand, the question remains whether it can also be used on satellite imagery, as that would further broaden the application range. DIAs commonly analyse video from shore-based camera stations, UAVs or XBandradars with durations of minutes and at framerates of 1–2 fps to find relevant wave frequencies. However, these requirements are typically not met by raw, temporally sparse satellite imagery. To overcome this problem a preprocessing step is utilized. Here, a sequence of 12 images of Capbreton, France, collected over a period of ∼1.5 min at a framerate of 1/8 fps by the Pleiades satellite, is augmented to a pseudo-video with a framerate of 1 fps. For this purpose a recently developed method is used, which considers spatial pathways of propagating waves for temporal video reconstruction. The resulting video is subsequently processed with the self-adaptive DIA. The combination of image augmentation with a frequency-based depth inversion method shows potential for broad application to temporally sparse satellite imagery and thereby aids in the effort towards broad usage of WCRS for mapping coastal bathymetry data around the globe.
By improving DIAs and their application to different instruments, this study has helped to increase the technological readiness of WCRS and its potential to be adopted by end-users. It was shown that WCRS can be performed on wave field records of land-based, airborne and space-born instruments and therewith on scales ranging from 𝑂(100 m2)(fixed camera) to 𝑂(100 km2)(X-band radar,satellite). The cost of WCRS is minor, as existing navigational X-band radars can be used, affordable UAVs and cameras, and accessible satellite data. X-band radars can operationally monitor complex coastal environments and recognize morphological trends, UAVs and cameras can be used for fast lean-and-mean mapping of coastal bathymetry, and by estimating depths from satellite imagery valuable data can be collected in otherwise data-poor environments. Yet, further steps should be taken in the accessibility, multifunctionality, quality, robustness and user-friendliness of WCRS. The key takeaway for effective WCRS monitoring is that future developments should strive towards integrated, self-adaptive software, which gives prompt visual response and requires little user-expertise. These measures reduce the difficulty to learn WCRS, increase its compatibility with data from different instruments (Xband-radars, cameras, UAVs, satellites) and thereby enable relatively easy coastal measurements. As a consequence WCRS becomes more adoptable by the coastal remote sensing community. With the exponential growth of data volumes worldwide, future data clouds may facilitate storage and offer future perspectives for online integration of data with numerical models and modern data science techniques like neural networks. This may create new possibilities for understanding system dynamics and thereby further aid decision makers in coastal management, the industry and the coast guard.","coastal remote sensing; mapping; depth inversion; wave field video; operational monitoring; on-the-fly processing; self-adaptive algorithms; XBand-radar; camera; UAV; drone; satellite","en","doctoral thesis","","978-94-6384-377-5","","","","","","","","","Coastal Engineering","","",""
"uuid:1cd3a854-bd68-46ac-98f6-09db88bc0766","http://resolver.tudelft.nl/uuid:1cd3a854-bd68-46ac-98f6-09db88bc0766","Understanding radar backscatter sensitivity to vegetation water dynamics: Sub-daily variations in ground-based experiments","Vermunt, P.C. (TU Delft Water Resources)","Steele-Dunne, S.C. (promotor); van de Giesen, N.C. (promotor); Delft University of Technology (degree granting institution)","2022","Observing vegetation water dynamics from space offers insights into plant-water relations and water and carbon fluxes across ecosystems at local to global scales. A promising technique to observe water in the vegetation layer is radar, an active form of microwave remote sensing. Interactions between microwaves and vegetation material depend on dielectric properties of the vegetation tissue, which are a function of water content. The research presented within this thesis aims to extend our physical understanding of the relationship between vegetation water dynamics and radar backscatter. The particular focus was on sub-daily dynamics, motivated by the dynamic nature of plantwater interactions and developments in the availability of sub-daily spaceborne radar observations. Moreover, we examined the effect of vertical water dynamics inside the vegetation layer on backscatter, which is relevant for better understandingwhich parts of the vegetation layer control the signal. To limit complexity, we focused on homogeneous corn fields. During ground-based experimental campaigns, we collected scatterometer data in vertical (VV), horizontal (HH) and cross (VH and HV) polarizations, and extensive measurements of water dynamics from these fields. These datasets were analyzed using statistical analyses and electromagnetic models.","Microwave remote sensing; vegetation water content; diurnal cycle; leaf surface water; soil moisture; corn field; L-band; tower-based scatterometer","en","doctoral thesis","","978-94-6421-791-9","","","","","","","","","Water Resources","","",""
"uuid:724acbc5-64b6-41d9-8142-dea2b137b8af","http://resolver.tudelft.nl/uuid:724acbc5-64b6-41d9-8142-dea2b137b8af","Aerosol Absorption from Global Satellite Measurements in the Ultra-Violet: From Qualitative Aerosol Index to Quantitative Aerosol Absorptive Properties","Sun, J. (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI))","Levelt, Pieternel Felicitas (promotor); Veefkind, j. Pepijn (copromotor); Delft University of Technology (degree granting institution)","2022","Atmospheric aerosols are solid or liquid particles suspended in the air. The majority of them are produced by natural processes, including sea salt from oceans, mineral dust from (semi-)arid regions, carbon containing particles from wildfires, and sulfates and ash from volcanic activities. Anthropogenic aerosols are produced by industrial activities, power generation, transportation, agriculture, and human-induced biomass burning events. Depending on the meteorological conditions, aerosol particles can stay in the atmosphere for several hours to several months and can be transported over long distances, causing adverse effects on human health, visibility and climate.
This thesis focuses on the aerosol optical properties, particularly the light absorption of the aerosol particles that has significant effects on the Earth’s climate system.
This thesis starts with a general introduction of atmospheric aerosols, including its sources, categories, physical properties and measurement techniques (Chapter 1). Next, the Ultra-Violet Aerosol Index (UVAI) is introduced, which is calculated from satellite measurements of the radiance at two wavelengths in the UV. UVAI contains information of aerosol absorption, and it has a very long and
almost continuous data record starting in 1978. Direct use of UVAI is challenging because it is not a geophysical quantity, but a numerical index. The objective of this thesis is to derive quantitative properties on aerosol absorption from the UVAI (e.g. single scattering albedo, absorption aerosol optical depth) that can be directly used in aerosol radiative transfer assessments. Two types of methods have been developed, i.e. physically-based methods and statistically-based methods. The first compares the observed UVAI to the one simulated by radiative transfer models. The second uses Machine Learning algorithms trained by existing data sets.
The physically-based methods have been applied to quantify aerosol absorption of several large scale wildfires (Chapter 2 and 3). An important challenge of these method is that assumptions have to be made on the aerosol micro-physical properties, leading to significant uncertainties in the results, whereas theMachine Learning-based methods can avoid this kind of assumptions. Chapter 3 investigates the feasibility to quantify aerosol absorption from UVAI using a Machine Learning algorithm. Despite the higher computational efficiency and better results, the application of such data-driven methods is still restricted by the limited data on the aerosol vertical distribution. Therefore, in Chapter
4, a database of aerosol height is created from a chemistry transport model. This database is applied in Chapter 5, where a Deep Neural Network method is used to derive the quantitative aerosol absorptive properties from the OMI/Aura UVAI for the period from 2006 to 2019. In comparison to ground-based observations, the results of the Deep Neural Network agree better than satellite retrievals and also better than chemistry transport model simulations.
This thesis demonstrates the feasibility of deriving quantitative aerosol absorptive properties from the satellite retrieved UVAI.We use traditional radiative transfer simulations meanwhile investigating the new possibilities of data-driven methods in aerosol remote sensing. Although the retrieval results are encouraging, there remain limitations and challenges which need to be addressed. These are discussed in Chapter 6 with corresponding suggestions and prospects. Despite the challenges, it is expected that a synthetic database of global aerosol absorption can be derived fromUVAI observations provided by multiple satellite products. Such a data set will make great contributions to quantify the effect of absorbing aerosols on the climate system.","Atmospheric Remote Sensing; aerosol climatology; Absorbing aerosol; Aerosol; Aerosol optical property","en","doctoral thesis","","9789463843065","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:8938bc7b-27e7-4b72-b744-1d8a1b0928a5","http://resolver.tudelft.nl/uuid:8938bc7b-27e7-4b72-b744-1d8a1b0928a5","Remote sensing-based prediction of forest fire characteristics","Maffei, C. (TU Delft Optical and Laser Remote Sensing)","Lindenbergh, R.C. (promotor); Menenti, M. (promotor); Delft University of Technology (degree granting institution)","2022","Forest fires are a major ecosystem disturbance at global scale, put pressure on agencies in charge of citizens and infrastructure security and cause unvaluable human losses. Fires are controlled by multiple static and dynamic drivers related to topography, land cover, climate, weather, and anthropic activity. Among these, weather is an active driver of live and dead fuel moisture, which has a direct effect on fire occurrence and behaviour. As a result, in areas experiencing prolonged droughts and heat waves, altered meteorological patterns lead to increased frequency and intensity of forest fires. The operational response of governments, local authorities, forest managers and civil protection agencies in charge of managing forest fires is informed by the assessment of factors controlling fire occurrence and behaviour, often synthesised in maps of fire danger. Danger is defined as the resultant of all factors affecting the inception, spread, and difficulty of control of fires, and it is typically expressed in the form of an index. Key contributors to fire danger are fuel type, amount, and conditions, notably with respect to moisture content. Remote sensing measurements in the shortwave infrared are sensitive to water content of live fuels, while measurements in the thermal infrared allow the detection of vegetation stress conditions due to vapour pressure deficit. In fact, several scholars proved that satellite estimates of vegetation water content and of land surface temperature could be effectively used to predict fire occurrence. Nevertheless, to the best of this author’s knowledge, no research was previously published connecting pre-fire remote sensing measurements to fire behaviour characteristics. This clearly identifies a knowledge gap which needs further investigation and that can be translated in the following research question: to what extent can remote sensing of forest condition be used to predict fire behaviour characteristics and assess the probability of extreme events? The research described in this dissertation aimed at developing methods based on pre-fire optical and thermal remote sensing observations of forests for the prediction of fire behaviour characteristics. The study was carried out in Campania, Italy (13595 km2), one of the most densely populated and fire affected regions in the Mediterranean. Data on all fire events recorded between 2002 and 2011 was provided by Carabinieri (Italian national gendarmerie) forest fire preparedness unit (Nucleo Informativo Antincendio Boschivo, NIAB). The study made use of MODIS land surface temperature (LST) and surface reflectance collection 6 products, which are publicly available on the USGS Land Processes Distributed Active Archive Center (LP DAAC). Approach was probabilistic in nature, trying to relate pre-fire satellite observations of vegetation conditions to the probability distributions of burned area, fire duration and rate of spread. Efforts initially focussed on assessing LST anomaly and its effect on fire behaviour characteristics. LST anomaly is a measure of excess enthalpy stored in fuels. It controls the probability of flames extinction and thus fire duration. First, a climatology of LST was constructed from the longest available time series of daily MODIS LST by means of the Harmonic Analysis of Time Series (HANTS) algorithm. HANTS was then used to construct annual models of daily LST. Finally, the daily LST anomaly was evaluated as the difference between the annual model and the climatology. Fires in the database were then associated with LST anomaly values recorded at their corresponding location on the day prior to the event. Probability distribution functions of log-transformed burned area (normal), log-transformed fire duration (generalised extreme value, GEV) and log-transformed rate of spread (Weibull) where then determined in ten decile bins of LST anomaly. The mean and the standard deviation of the normal distribution of log-transformed burned area showed a clear linear dependence on LST anomaly (r2=0.81, p<0.001 and r2=0.52, p<0.05 respectively), indicating an increase in the probability of large fires with increasing LST anomaly. Similarly, a marked linear dependence on LST anomaly was found for the location (r2=0.78, p<0.001), scale (r2=0.79, p<0.001) and shape (r2=0.87, p<0.001) of the GEV distribution of log-transformed fire duration, favouring longer fire duration with increasing LST anomaly. Conversely, the LST anomaly had a limited effect on the Weibull distribution of log-transformed rate of spread, with scale and shape showing slightly decreasing trends (r2=0.50, p<0.05 and r2=0.54, p<0.05 respectively). A likelihood ratio test showed that the probability models of log-transformed burned area, fire duration and rate of spread conditional to LST anomaly (alternative models) allowed the rejection of the corresponding unconditional models fitting all data (null models), confirming that LST anomaly is a covariate of burned area, fire duration and, to a lesser extent, rate of spread. These results are in line with expectations from models of the combustion process. Following a similar line of reasoning, this study further focussed on remote sensing of live fuel moisture content (LFMC). This vegetation property controls ignition delay, and thus affects flames propagation. The first step was the construction of a novel spectral index, the perpendicular moisture index (PMI), specifically designed to be sensitive to LFMC. The PMI was developed from simulated vegetation spectral data convolved to MODIS bands by noting that in the spectral reflectance subspace of MODIS bands 2 (0.86 µm) and 5 (1.24 µm) isolines of LFMC can be identified, and that these isolines are straight and parallel. By taking as a reference the line corresponding to LFMC=0 (completely dry vegetation), the PMI was calculated as the distance of measured reflectance from the reference line. The PMI is thus a measure of LFMC, and higher values of PMI correspond to higher moisture content. The index was found to be linearly related to LFMC, especially for dense vegetation cover (r2=0.70 when leaf area index is larger than 2, r2=0.87 when larger than 4). When vegetation cover is less dense, the contribution of soil background to the measured reflectance increases, and the PMI underestimates LFMC. PMI maps were produced from the MODIS 8-day composited reflectance product, and fires in the database were associated with the corresponding PMI value at the fire location in the pre-fire compositing period. Using the same approach adopted for LST anomaly, the probability distribution functions of log-transformed burned area, fire duration and rate of spread were determined in ten decile bins of PMI. The mean of the normal distribution of log-transformed burned area showed a clear linear dependence on PMI (r2=0.80, p<0.001), while no trend could be observed for standard deviation. A clear linear dependence on PMI was also found for scale and shape of the Weibull distribution of log-transformed rate of spread (r2=0.97, p<0.001 and r2=0.82, p<0.001 respectively). These results were further confirmed by a likelihood ratio test where the probability models of log-transformed burned area and rate of spread conditional to PMI allowed the rejection of the corresponding unconditional models fitting all data. Location and shape of the GEV distribution of log-transformed fire duration showed no significant linear trend with PMI, whereas scale showed a weak trend (r2=0.55, p<0.05). However, in the likelihood ratio test the probability model of log-transformed fire duration conditional to PMI failed to reject the corresponding unconditional model. These results showed that PMI is a covariate of burned area and rate of spread, as expected from flames propagation models, but not of fire duration. Predictions of fire characteristics based on concurrent observations of LST anomaly and PMI were compared with predictions based on the Fire Weather Index (FWI) System. This fire danger rating tool proved to be effective in several areas worldwide, including Europe. FWI values from weather reanalysis data were associated with fires in the database and were analysed with the same approach adopted for LST anomaly and PMI. It was found that parameters of the probability distribution function of log-transformed burned area and fire duration conditional to FWI System components followed clear linear trends, with increasing danger values leading to higher probabilities of large burned areas and long fire durations. Conversely, FWI System components were unrelated to the rate of spread. Trend analysis (coefficient of determination and p-value of the linear fit, Sen’s slope and Mann-Kendall test) and likelihood ratio tests were used to compare the trends in the parameters of the probability distributions of fire characteristics. It was shown that remote sensing predictions of burned area and fire duration were comparable or better than those from FWI, and that PMI is a good predictor of the rate of spread whereas FWI System components are not. The identified linear trends in the dependence of the parameters of the probability distribution of log-transformed burned area, fire duration and rate of spread on LST anomaly and on PMI allow the prediction of the probability of extreme events, conditional to ignition, as a function of pre-fire remote sensing observations. As both LST anomaly and PMI are good covariates of burned area, these two remote sensing observations of vegetation conditions can be used jointly to improve the prediction of the probability of fires larger than say, the 95th percentile of all events recorded in the study area (30 ha). It was found that the probability of a fire resulting in a burned area larger than 30 ha increases from 0.9% to 9.2% with pre-fire LST anomaly increasing from -2.1 to 4.3 K and increases from 1.8% to 7.4% with pre-fire PMI decreasing from 0.052 to -0.032. When the probability of fires exceeding 30.0 ha is modelled as a function of both LST anomaly and PMI, the probability increases from 0.5% to 12.7%. This confirms that the joint use of LST anomaly and PMI leads to improved predictions. The scientific community showed a consensus on the need to improve fire danger prediction through a more accurate assessment of live fuel condition. Existing fire danger rating systems estimate fuel moisture content from meteorological variables, which results in an undesired approximated solution due to underlying assumptions. Consequently, any direct observation of fuel moisture content has the potential to enable a better evaluation of fire occurrence and fire danger indices. From a remote sensing perspective, these considerations are translated in the research question on the need to understand to what extent can satellite measurements be used to predict forest fire behaviour characteristics. This research showed that remote sensing of vegetation in the optical and thermal domains allows the prediction of the probability distributions of fire behaviour characteristics such as burned area, duration, and rate of spread. These can be further used to evaluate the probability of extreme events, conditional to ignition, as a function of pre-fire remote sensing measurements, contributing to predict danger. It should be noted once more that this result was achieved by using pre-fire remote sensing observations, allowing the prediction of fire characteristics. In perspective, results showed in this dissertation can support the development of operational tools for forest managers and civil protection agencies in their fire preparedness activities.","Remote sensing; Earth observation; Forest fires; Fire danger; Fire burned area; Fire duration; Fire rate of spread; MODIS; Land surface temperature (LST); LST anomaly; Perpendicular Moisture Index (PMI); Live fuel moisture content (LFMC); Fire Weather Index (FWI); Probability of extreme events; Conditional probability distribution; Anderson-Darling goodness-of-fit; Generalized extreme value (GEV) distribution; Normal distribution; Weibull distribution; Time series; Harmonic Analysis of Time Series (HANTS)","en","doctoral thesis","","978-94-6384-275-4","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:4e7de687-3b15-4d01-8b2d-22c23437f179","http://resolver.tudelft.nl/uuid:4e7de687-3b15-4d01-8b2d-22c23437f179","Depth Inversion from Wave Frequencies in Temporally Augmented Satellite Video","Gawehn, M.A. (TU Delft Coastal Engineering; Deltares); Almar, Rafael (IRD-LEGOS); Bergsma, Erwin W. J. (Centre National pour l’Etudes Spatiales); de Vries, S. (TU Delft Coastal Engineering); Aarninkhof, S.G.J. (TU Delft Hydraulic Engineering)","","2022","Optical satellite images of the nearshore water surface offer the possibility to invert water depths and thereby constitute the underlying bathymetry. Depth inversion techniques based on surface wave patterns can handle clear and turbid waters in a variety of global coastal environments. Common depth inversion algorithms require video from shore-based camera stations, UAVs or Xband-radars with a typical duration of minutes and at framerates of 1–2 fps to find relevant wave frequencies. These requirements are often not met by satellite imagery. In this paper, satellite imagery is augmented from a sequence of 12 images of Capbreton, France, collected over a period of ∼1.5 min at a framerate of 1/8 fps by the Pleiades satellite, to a pseudo-video with a framerate of 1 fps. For this purpose, a recently developed method is used, which considers spatial pathways of propagating waves for temporal video reconstruction. The augmented video is subsequently processed with a frequency-based depth inversion algorithm that works largely unsupervised and is openly available. The resulting depth estimates approximate ground truth with an overall depth bias of −0.9 m and an interquartile range of depth errors of 5.1 m. The acquired accuracy is sufficiently high to correctly predict wave heights over the shoreface with a numerical wave model and to find hotspots where wave refraction leads to focusing of wave energy that has potential implications for coastal hazard assessments. A more detailed depth inversion analysis of the nearshore region furthermore demonstrates the possibility to detect sandbars. The combination of image augmentation with a frequency-based depth inversion method shows potential for broad application to temporally sparse satellite imagery and thereby aids in the effort towards globally available coastal bathymetry data.","satellite remote sensing; coastal depth inversion; Dynamic Mode Decomposition; ocean waves; Capbreton; New Aquitain; France","en","journal article","","","","","","","","","","Hydraulic Engineering","Coastal Engineering","","",""
"uuid:eb48f9dd-41ef-43b8-b91d-8afd51ffb14a","http://resolver.tudelft.nl/uuid:eb48f9dd-41ef-43b8-b91d-8afd51ffb14a","Evaluation of Creep Behavior of Soft Soils by Utilizing Multisensor Data Combined with Machine Learning","Kovacevic, Meho Sasa (University of Zagreb); Bačić, Mario (University of Zagreb); Librić, Lovorka (University of Zagreb); Gavin, Kenneth (TU Delft Geo-engineering)","","2022","To identify the unknown values of the parameters of Burger’s constitutive law, commonly used for the evaluation of the creep behavior of the soft soils, this paper demonstrates a procedure relying on the data obtained from multiple sensors, where each sensor is used to its best advantage. The geophysical, geotechnical, and unmanned aerial vehicle data are used for the development of a numerical model whose results feed into the custom-architecture neural network, which then provides information about on the complex relationships between the creep characteristics and soil displacements. By utilizing InSAR and GPS monitoring data, particle swarm algorithm identifies the most probable set of Burger’s creep parameters, eventually providing a reliable estimation of the long-term behavior of soft soils. The validation of methodology is conducted for the Oostmolendijk embankment in the Netherlands, constructed on the soft clay and peat layers. The validation results show that the application of the proposed methodology, which relies on multisensor data, can overcome the high cost and long duration issues of laboratory tests for the determination of the creep parameters and can provide reliable estimates of the long-term behavior of geotechnical structures constructed on soft soils","soft soil creep; Burger’s model; neural network; particle swarm optimization; remote sensing; nondestructive testing","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:35447f98-0ead-451b-91cd-54bb3de2bea3","http://resolver.tudelft.nl/uuid:35447f98-0ead-451b-91cd-54bb3de2bea3","Lessons for Remote Post-earthquake Reconnaissance from the 14 August 2021 Haiti Earthquake","Whitworth, Michael R. Z. (AECOM, London); Giardina, Giorgia (TU Delft Geo-engineering); Penney, Camilla (University of Cambridge); Di Sarno, Luigi (University of Liverpool); Adams, Keith (Brunel University London); Kijewski-Correa, Tracy (University of Notre Dame); Black, Jacob (AKT II, London); Foroughnia, Fatemeh (TU Delft Geo-engineering); Macchiarulo, V. (TU Delft Geo-engineering)","","2022","On 14th August 2021, a magnitude 7.2 earthquake struck the Tiburon Peninsula in the Caribbean nation of Haiti, approximately 150 km west of the capital Port-au-Prince. Aftershocks up to moment magnitude 5.7 followed and over 1,000 landslides were triggered. These events led to over 2,000 fatalities, 15,000 injuries and more than 137,000 structural failures. The economic impact is of the order of US$1.6 billion. The on-going Covid pandemic and a complex political and security situation in Haiti meant that deploying earthquake engineers from the UK to assess structural damage and identify lessons for future building construction was impractical. Instead, the Earthquake Engineering Field Investigation Team (EEFIT) carried out a hybrid mission, modelled on the previous EEFIT Aegean Mission of 2020. The objectives were: to use open-source information, particularly remote sensing data such as InSAR and Optical/Multispectral imagery, to characterise the earthquake and associated hazards; to understand the observed strong ground motions and compare these to existing seismic codes; to undertake remote structural damage assessments, and to evaluate the applicability of the techniques used for future post-disaster assessments. Remote structural damage assessments were conducted in collaboration with the Structural Extreme Events Reconnaissance (StEER) team, who mobilised a group of local non-experts to rapidly record building damage. The EEFIT team undertook damage assessment for over 2,000 buildings comprising schools, hospitals, churches and housing to investigate the impact of the earthquake on building typologies in Haiti. This paper summarises the mission setup and findings, and discusses the benefits, and difficulties, encountered during this hybrid reconnaissance mission.","remote reconnaissance; earthquake; building damage; remote sensing; landslides; data collection; InSAR; multispectral imagery","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:ebc80097-dc8a-44b4-9252-8413f8efa121","http://resolver.tudelft.nl/uuid:ebc80097-dc8a-44b4-9252-8413f8efa121","Monitoring deformations of infrastructure networks: A fully automated GIS integration and analysis of InSAR time-series","Macchiarulo, V. (University of Bath); Milillo, Pietro (University of Houston); Blenkinsopp, Chris E. (University of Bath); Giardina, Giorgia (TU Delft Geo-engineering)","","2022","Ageing stock and extreme weather events pose a threat to the safety of infrastructure networks. In most countries, funding allocated to infrastructure management is insufficient to perform systematic inspections over large transport networks. As a result, early signs of distress can develop unnoticed, potentially leading to catastrophic structural failures. Over the past 20 years, a wealth of literature has demonstrated the capability of satellite-based Synthetic Aperture Radar Interferometry (InSAR) to accurately detect surface deformations of different types of assets. Thanks to the high accuracy and spatial density of measurements, and a short revisit time, space-borne remote-sensing techniques have the potential to provide a cost-effective and near real-time monitoring tool. Whilst InSAR techniques offer an effective approach for structural health monitoring, they also provide a large amount of data. For civil engineering procedures, these need to be analysed in combination with large infrastructure inventories. Over a regional scale, the manual extraction of InSAR-derived displacements from individual assets is extremely time-consuming and an automated integration of the two datasets is essential to effectively assess infrastructure systems. This paper presents a new methodology based on the fully automated integration of InSAR-based measurements and Geographic Information System-infrastructure inventories to detect potential warnings over extensive transport networks. A Sentinel dataset from 2016 to 2019 is used to analyse the Los Angeles highway and freeway network, while the Italian motorway network is evaluated by using open access ERS/Envisat datasets between 1992 and 2010, COSMO-SkyMed datasets between 2008 and 2014 and Sentinel datasets between 2014 and 2020. To demonstrate the flexibility of the proposed methodology to different SAR sensors and infrastructure classes, the analysis of bridges and viaducts in the two test areas is also performed. The outcomes highlight the potential of the proposed methodology to be integrated into structural health monitoring systems and improve current procedures for transport network management.","Italy; Los Angeles; MT-InSAR; bridges; critical infrastructure; early warning; infrastructure resilience; remote sensing; roadway; transport networks","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:0dd836b3-87d6-4e3d-b706-296d1e1062a1","http://resolver.tudelft.nl/uuid:0dd836b3-87d6-4e3d-b706-296d1e1062a1","Assessing and Modelling Climate Optimal Flights Using Open Surveillance and Remote Sensing Data","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Dedoussi, I.C. (TU Delft Aircraft Noise and Climate Effects); Stam, D.M. (TU Delft Astrodynamics & Space Missions); Hoekstra, J.M. (TU Delft Control & Simulation)","Lovell, Dave (editor)","2022","Sustainability is the biggest challenge facing the aerospace industry today. With the global number of flights expected to rise, the climate impact of aviation will continue to increase. Current research states that the rerouting of aircraft through wind-optimisation for the purpose of fuel usage minimisation and emission reduction is an effective sustainability contribution. However, these routing models only optimize for minimum fuel burn, not necessarily minimum climate impact. Flying efficiently through wind fields could mean flying through regions with higher climate impact, for example, where warming contrails are formed. This potentially forfeits the advantage of the reduced emissions from the wind-optimized route. By bringing together fields such as satellite remote sensing, atmospheric science and aircraft surveillance data, a climate optimized free routing model can be made. This paper creates a climate optimized free routing airspace model by incorporating knowledge from the aforementioned fields and existing wind-optimization models with AI and open-source tools.","Sustainability; Remote Sensing; Atmospheric Science; OpenSky; Aircraft Surveillance Data; AI; Contrails","en","conference paper","FAA & Eurocontrol","","","","","","","","","","Control & Simulation","","",""
"uuid:400c8cba-e200-4856-a5ce-22f4402e8a61","http://resolver.tudelft.nl/uuid:400c8cba-e200-4856-a5ce-22f4402e8a61","Scalable Water Balances from Earth Observations (SWEO): results from 50 years of remote sensing in hydrology","Hessels, T.M. (TU Delft Water Resources; IHE Delft Institute for Water Education; IrriWatch); Davids, Jeffrey C. (California State University, Chico; Davids Engineering); Bastiaanssen, W.G.M. (TU Delft Water Resources; IrriWatch)","","2022","Strategic planning of water management at the river-basin scale requires (1) measurement and accounting of individual hydrological processes, (2) quantification of water resources, and (3) their optimal allocation. Scalable Water Balances from Earth Observations (SWEO) is an open-access parameterization enabling automated reporting of water footprints and Sustainable Development Goal (SDG) indicators. We present its systematic arrangement and input datasets, and demonstrate its accuracy by independent riverflow measurements. We also review some achievements in remote sensing for hydrology during the last 50 years in quantifying hydrological and water management processes, flows, fluxes and changes in storage from various independent sources; and append mathematical formulations.","50 years of remote sensing hydrology; internal calibration; open-access Earth observation databases; rapid water accounting; scalable water balance","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:edae6ce7-e633-44d3-99f4-f2f2f0ce0193","http://resolver.tudelft.nl/uuid:edae6ce7-e633-44d3-99f4-f2f2f0ce0193","Examining Contrail Formation Models with Open Flight and Remote Sensing Data","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2022","One of the biggest challenges facing the aerospace industry today is its sustainability. As the number of flights is expected to rise globally, aviation’s climate impact will continue to increase. Current research has extensively addressed the rerouting of aircraft through wind-optimization in order to minimize fuel burn and emissions. Such optimization is currently implemented for flight planning. Although this strategy is optimized for fuel burn and emissions, it does not necessarily minimize the overall climate impact. Navigating optimally through wind fields could mean flying through regions with a higher climate impact, where warming contrails are formed. This can occur when contrails trap outgoing terrestrial radiation and so contribute to global warming. This warming contrail creation could potentially forfeit the climate gain of the reduced emissions from the wind-optimized route. In order to implement such a climate-optimized routing model, knowledge about the atmospheric conditions under which contrails form is required. One existing theorem is the Schmidt-Appleman Criterion, which uses the air temperature, relative humidity and ambient air pressure to determine whether contrail formation is possible. In addition, the ice-supersaturation criterion model indicates contrail persistence. In this paper, multiple open data sources are used to examine the use of this established criterion, to evaluate the appropriateness of these data sources for future use in a climate-optimized routing model. Based on the obtained results, we show that, with these data sources, the combination of Schmidt-Appleman and the ice-supersaturation criterion can produce a more reliable determination of contrail formation. The results can be used for an improved unified and data-driven model for the purposes of climate-optimized routing.","Sustainability; Contrails; Remote Sensing; Atmospheric Science; OpenSky; Aircraft Surveillance Data","en","conference paper","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-05-10","","","Control & Simulation","","",""
"uuid:96c4918b-4df6-4135-bff4-e9121e11a245","http://resolver.tudelft.nl/uuid:96c4918b-4df6-4135-bff4-e9121e11a245","Remote Sensing of Surface Melt on Antarctica: Opportunities and Challenges","de Roda Husman, S. (TU Delft Physical and Space Geodesy); Hu, Zhongyang (Universiteit Utrecht); Wouters, B. (TU Delft Physical and Space Geodesy); Munneke, Peter Kuipers (Universiteit Utrecht); Veldhuijsen, Sanne (Universiteit Utrecht); Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning; Katholieke Universiteit Leuven)","","2022","Surface melt is an important driver of ice shelf disintegration and its consequent mass loss over the Antarctic Ice Sheet. Monitoring surface melt using satellite remote sensing can enhance our understanding of ice shelf stability. However, the sensors do not measure the actual physical process of surface melt, but rather observe the presence of liquid water. Moreover, the sensor observations are influenced by the sensor characteristics and surface properties. Therefore, large inconsistencies can exist in the derived melt estimates from different sensors. In this study, we apply state-of-the-art melt detection algorithms to four frequently used remote sensing sensors, i.e., two active microwave sensors, which are Advanced Scatterometer (ASCAT) and Sentinel-1, a passive microwave sensor, i.e., Special Sensor Microwave Imager/Sounder (SSMIS), and an optical sensor, i.e., Moderate Resolution Imaging Spectroradiometer (MODIS). We intercompare the melt detection results over the entire Antarctic Ice Sheet and four selected study regions for the melt seasons 2015-2020. Our results show large spatiotemporal differences in detected melt between the sensors, with particular disagreement in blue ice areas, in aquifer regions, and during wintertime surface melt. We discuss that discrepancies between sensors are mainly due to cloud obstruction and polar darkness, frequency-dependent penetration of satellite signals, temporal resolution, and spatial resolution, as well as the applied melt detection methods. Nevertheless, we argue that different sensors can complement each other, enabling improved detection of surface melt over the Antarctic Ice Sheet.","Antarctic Ice Sheet; Antarctica; Earth Observation; ice shelves; Land surface; melt detection; multi-source remote sensing; Ocean temperature; polar regions; satellite observations; Sea surface; Sensors; Surface topography; Surface treatment","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:258deab2-3e9e-471a-a675-39df97b3e376","http://resolver.tudelft.nl/uuid:258deab2-3e9e-471a-a675-39df97b3e376","Damage detection on antarctic ice shelves using the normalised radon transform","Izeboud, M. (TU Delft Mathematical Geodesy and Positioning); Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning; Katholieke Universiteit Leuven)","","2022","Areas of structural damage mechanically weaken Antarctic ice shelves. This potentially preconditions ice shelves for disintegration and enhanced grounding line retreat. The development of damage and its feedback on marine ice sheet dynamics has been identified as key to future ice shelf stability and sea level contributions from Antarctica. However, it is one of the least understood processes that impact ice shelf instability since quantifying damage efficiently and accurately is a challenging task. Challenges relate to the complex surface of Antarctica, variations in viewing-illumination geometry, snow or cloud cover and variable signal-to-noise levels in satellite imagery. Therefore, automated damage assessment approaches require careful pre- and post-processing, lacking the option to be applied to wider spatiotemporal domains. Simultaneously, studies that use manual mapping are usually limited due to the effort required for extensive mapping, which either results in a limited spatial domain or the use of low resolution data.
This study proposes the NormalisEd Radon transform Damage detection (NeRD) method to detect damage features and their orientations from multi-source satellite imagery. NeRD performs robust, high resolution, large-scale damage assessments. NeRD is applied to the ice shelves in the Amundsen Sea Embayment (ASE) and validated with both manually labelled and existing fracture maps. Validation shows that NeRD detects damage with high recall and provides an accurate physical representation of multi-scale damage features and their orientation. Sensitivity analyses indicate NeRD is robust to different resolution parameter settings. NeRD consistently detects damage for different data sources ranging from optical Landsat 7/8 and Sentinel-2 optical to Synthetic Aperture Radar Sentinel-1 data. Therefore, NeRD paves the way for synergistic multi-source damage detection that overcomes remaining limitations from individual sources. Results show varying damage patterns on the ice shelves in the ASE area in austral summer 2020–2021, with most damage located on the Pine Island, Crosson and Thwaites ice shelves. We show a damage increase on the Pine Island ice shelf between 2013–2019, and display advection and rotation of crevasses. The detected damage orientation can provide insight in the type of crevasse opening mode and the development of damage over time. The damage maps produced with NeRD can help evaluate ice sheet models or machine learning approaches, improving our understanding of damage evolution.","Damage detection; Antarctic ice shelves; Multi-source remote sensing; Normalised radon transform","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:16667492-fee8-49c9-88ff-1f32745430aa","http://resolver.tudelft.nl/uuid:16667492-fee8-49c9-88ff-1f32745430aa","Crop Water Productivity Mapping and Benchmarking Using Remote Sensing and Google Earth Engine Cloud Computing","Ghorbanpour, Ali Karbalaye (University of California); Kisekka, Isaya (University of California); Afshar, Abbas (Iran University of Science and Technology); Hessels, T.M. (TU Delft Water Resources); Taraghi, Mahdi (Urmia University); Hessari, Behzad (Urmia University); Tourian, Mohammad J. (University of Stuttgart); Duan, Zheng (Lund University)","","2022","Scarce water resources present a major hindrance to ensuring food security. Crop water productivity (WP), embraced as one of the Sustainable Development Goals (SDGs), is playing an integral role in the performance-based evaluation of agricultural systems and securing sustainable food production. This study aims at developing a cloud-based model within the Google Earth Engine (GEE) based on Landsat -7 and -8 satellite imagery to facilitate WP mapping at regional scales (30-m resolution) and analyzing the state of the water use efficiency and productivity of the agricultural sector as a means of benchmarking its WP and defining local gaps and targets at spatiotemporal scales. The model was tested in three major agricultural districts in the Lake Urmia Basin (LUB) with respect to five crop types, including irrigated wheat, rainfed wheat, apples, grapes, alfalfa, and sugar beets as the major grown crops. The actual evapotranspiration (ET) was estimated using geeSEBAL based on the Surface Energy Balance Algorithm for Land (SEBAL) methodology, while for crop yield estimations Monteith’s Light Use Efficiency model (LUE) was employed. The results indicate that the WP in the LUB is below its optimum targets, revealing that there is a significant degree of work necessary to ameliorate the WP in the LUB. The WP varies between 0.49–0.55 (kg/m3) for irrigated wheat, 0.27–0.34 for rainfed wheat, 1.7–2.2 for apples, 1.2–1.7 for grapes, 5.5–6.2 for sugar beets, and 0.67–1.08 for alfalfa, which could be potentially increased up to 80%, 150%, 76%, 83%, 55%, and 48%, respectively. The spatial variation of the WP and crop yield makes it feasible to detect the areas with the best and poorest on-farm practices, thereby facilitating the better targeting of resources to bridge the WP gap through water management practices. This study provides important insights into the status and potential of WP with possible worldwide applications at both farm and government levels for policymakers, practitioners, and growers to adopt effective policy guidelines and improve on-farm practices.","crop water productivity; Google Earth Engine; Lake Urmia; Landsat; remote sensing; SEBAL","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:ebfa8556-22d7-4ef8-afc1-740922207f27","http://resolver.tudelft.nl/uuid:ebfa8556-22d7-4ef8-afc1-740922207f27","Quantifying NOxEmissions from U.S. Oil and Gas Production Regions Using TROPOMI NO2","Dix, Barbara (University of Colorado); Francoeur, Colby (University of Colorado; National Oceanic and Atmospheric Administration); Li, Meng (University of Colorado; National Oceanic and Atmospheric Administration); Serrano Calvo, R. (TU Delft Atmospheric Remote Sensing); Levelt, Pieternel Felicitas (TU Delft Atmospheric Remote Sensing; University Corporation for Atmospheric Research; Royal Netherlands Meteorological Institute (KNMI)); Veefkind, j. Pepijn (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); McDonald, Brian C. (National Oceanic and Atmospheric Administration); De Gouw, Joost (University of Colorado)","","2022","The production of crude oil and natural gas is associated with emissions of air pollutants, such as nitrogen oxides (NOx = NO + NO2) and volatile organic compounds, which are precursors for the formation of ground-level ozone. Knowledge of these emissions is critical to the understanding and mitigation of local air quality. NOx emissions from oil and gas production activities are not well described in commonly used emission inventories, and discrepancies of several factors have been found in the past. Here we present an easy and computationally efficient method to quantify NOx emissions from satellite NO2 observations that can be applied to evaluate common emission inventories and provide timely input for chemistry transport models. Using NO2 columns from the TROPOspheric Monitoring Instrument (TROPOMI), we calculated annually averaged NOx emissions from the divergence of NO2 column fluxes for six oil and gas production regions in the United States. Derived NOx emissions for the years 2018 to 2020 range between 4.8 and 81.1 t/day, and observed trends over time are consistent with changes in industrial activity. To evaluate the method, we compared our results with the fuel-based oil and gas NOx inventory (FOG) and performed sensitivity studies using model output from the Weather Research Forecasting model with Chemistry (WRF-Chem). We found that annually averaged NOx emissions from oil and gas production activities can in most cases be calculated within an uncertainty of 50%, while simultaneously derived emission maps show the spatial distribution of NOx emissions with a high level of detail. For future use, this method can easily be applied globally.","air quality; emissions; nitrogen oxides; oil and gas; remote sensing; satellite","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Atmospheric Remote Sensing","","",""
"uuid:f1dd8107-850b-4bf4-a70b-fa124a6ddc33","http://resolver.tudelft.nl/uuid:f1dd8107-850b-4bf4-a70b-fa124a6ddc33","Hydroclimatic adaptation critical to the resilience of tropical forests","Singh, Chandrakant (Stockholm University); van der Ent, R.J. (TU Delft Water Resources; Universiteit Utrecht); Wang-Erlandsson, Lan (Stockholm University); Fetzer, Ingo (Stockholm University)","","2022","Forest and savanna ecosystems naturally exist as alternative stable states. The maximum capacity of these ecosystems to absorb perturbations without transitioning to the other alternative stable state is referred to as ‘resilience’. Previous studies have determined the resilience of terrestrial ecosystems to hydroclimatic changes predominantly based on space-for-time substitution. This substitution assumes that the contemporary spatial frequency distribution of ecosystems’ tree cover structure holds across time. However, this assumption is problematic since ecosystem adaptation over time is ignored. Here we empirically study tropical forests’ stability and hydroclimatic adaptation dynamics by examining remotely sensed tree cover change (ΔTC; aboveground ecosystem structural change) and root zone storage capacity (Sr; buffer capacity towards water-stress) over the last two decades. We find that ecosystems at high (>75%) and low (<10%) tree cover adapt by instigating considerable subsoil investment, and therefore experience limited ΔTC—signifying stability. In contrast, unstable ecosystems at intermediate (30%–60%) tree cover are unable to exploit the same level of adaptation as stable ecosystems, thus showing considerable ΔTC. Ignoring this adaptive mechanism can underestimate the resilience of the forest ecosystems, which we find is largely underestimated in the case of the Congo rainforests. The results from this study emphasise the importance of the ecosystem's temporal dynamics and adaptation in inferring and assessing the risk of forest-savannah transitions under rapid hydroclimatic change.","alternative stable states; ecosystem change; forest-savanna transition; remote sensing; spatio-temporal approach; subsoil adaptation; transient state","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:c915fe68-a425-4e6a-ae6f-9cb4846f9993","http://resolver.tudelft.nl/uuid:c915fe68-a425-4e6a-ae6f-9cb4846f9993","Managing mangroves and coastal land cover in the Mekong Delta","Phan, M.H. (TU Delft Coastal Engineering; Ministry of Agriculture and Rural Development); Stive, M.J.F. (TU Delft Coastal Engineering)","","2022","Mangroves play an important role in sustaining a healthy coastal environment, providing a natural habitat to various species, a stable shoreline and forestry products. However, the extent of mangroves developed along the tidal coast of the Mekong delta in southern Vietnam has faced and still faces the impact from both natural and anthropogenic drivers. Since the area of mangroves in the coastal Mekong delta is not well documented, this study aims to quantitatively document the evolution of the mangrove area over the past 48 years, i.e. between 1973 and 2020. Satellite Landsat images, along with a classification method comprising Iso Cluster and Maximum Likelihood algorithms, have been used for mapping land cover types including mangroves, aquaculture, soils, plants and water surfaces along the coastal districts of the Mekong delta. The study shows that remote sensing and GIS techniques can be applied to obtain mapping of the land cover, as well as detect and analyse spatial and temporal changes caused by e.g. coastal erosion or aquaculture expansion. The findings reveal that the total mangrove area of an estimated 185,800 ha in 1973 decreased significantly to 102,160 ha in 2020. Approximately 2150 ha/yr of the total mangrove loss over 1973–2020 was due to invasion by aquaculture, while roughly 430 ha/yr was lost due to coastal erosion. A slight increase in mangrove area occurred since 2010 as a result of the implementation of a series of projects to protect against coastal erosion and to restore mangroves by the Vietnamese government and international non-governmental and governmental organizations, although the success rates of mangrove restoration are relatively low. The survival of mangrove forests in the Mekong delta is related to the main pressure drivers: pollution, land use conversion, insufficient sediment sources, coastal erosion and coastal mangrove squeeze. Therefore, an integrated mangroves and shrimp farming model is one of the most appropriate approaches to achieve a beneficial balance between both aquaculture and mangroves.","Aquaculture; Land-cover; Mangroves; Mekong delta; Remote sensing","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-08-31","","","Coastal Engineering","","",""
"uuid:d37d12bd-ad7c-4567-9c05-649f310a5806","http://resolver.tudelft.nl/uuid:d37d12bd-ad7c-4567-9c05-649f310a5806","Calibration and Validation of SWAT Model by Using Hydrological Remote Sensing Observables in the Lake Chad Basin","Bennour, Ali (Chinese Academy of Sciences; University of Chinese Academy of Sciences; Commissariat Regional au Development Agricole); Jia, Li (Chinese Academy of Sciences); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Zheng, Chaolei (Chinese Academy of Sciences); Zeng, Yelong (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Barnieh, Beatrice Asenso (Chinese Academy of Sciences; University of Energy and Natural Resources); Jiang, Min (Chinese Academy of Sciences)","","2022","Model calibration and validation are challenging in poorly gauged basins. We developed and applied a new approach to calibrate hydrological models using distributed geospatial remote sensing data. The Soil and Water Assessment Tool (SWAT) model was calibrated using only twelve months of remote sensing data on actual evapotranspiration (ETa) geospatially distributed in the 37 sub-basins of the Lake Chad Basin in Africa. Global sensitivity analysis was conducted to identify influential model parameters by applying the Sequential Uncertainty Fitting Algorithm–version 2 (SUFI-2), included in the SWAT-Calibration and Uncertainty Program (SWAT-CUP). This procedure is designed to deal with spatially variable parameters and estimates either multiplicative or additive corrections applicable to the entire model domain, which limits the number of unknowns while preserving spatial variability. The sensitivity analysis led us to identify fifteen influential parameters, which were selected for calibration. The optimized parameters gave the best model performance on the basis of the high Nash–Sutcliffe Efficiency (NSE), Kling–Gupta Efficiency (KGE), and determination coefficient (R2). Four sets of remote sensing ETa data products were applied in model calibration, i.e., ETMonitor, GLEAM, SSEBop, and WaPOR. Overall, the new approach of using remote sensing ETa for a limited period of time was robust and gave a very good performance, with R2 > 0.9, NSE > 0.8, and KGE > 0.75 applying to the SWAT ETa vs. the ETMonitor ETa and GLEAM ETa. The ETMonitor ETa was finally adopted for further model applications. The calibrated SWAT model was then validated during 2010–2015 against remote sensing data on total water storage change (TWSC) with acceptable performance, i.e., R2 = 0.57 and NSE = 0.55, and remote sensing soil moisture data with R2 and NSE greater than 0.85.","African Sahel; ETMonitor evapotranspiration; hydrological modeling; hydrological remote sensing observables; limited calibration; SWAT model","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:bf74fbdc-0bb8-49bc-83ac-2583e48094be","http://resolver.tudelft.nl/uuid:bf74fbdc-0bb8-49bc-83ac-2583e48094be","Wind-Wave Attenuation in Arctic Sea Ice: A Discussion of Remote Sensing Capabilities","Collard, Fabrice (OceanDataLab); Marié, Louis (Univ. Brest/CNRS/Ifremer/IRD); Nouguier, Frédéric (Univ. Brest/CNRS/Ifremer/IRD); Kleinherenbrink, M. (TU Delft Mathematical Geodesy and Positioning); Ehlers, F. (TU Delft Physical and Space Geodesy); Ardhuin, Fabrice (Univ. Brest/CNRS/Ifremer/IRD)","","2022","Wind-generated waves strongly interact with sea ice and impact air-sea exchanges, operations at sea, and marine life. Unfortunately, the dissipation of wave energy is not well quantified and its possible effect on upper ocean mixing and ice drift is still mysterious. As the Arctic is opening up and wave energy increases, the limited amount of in situ observations is a clear limitation to our scientific understanding. Both radar and optical remote sensing has revealed the frequent presence of waves in ice, and could be used more systematically to investigate wave-ice interactions. Here we show that, in cloud-free conditions, Sentinel-2 images exhibit brightness modulations in ice-covered water, consistent with the presence of waves measured a few hours later by the ICESat-2 laser altimeter. We show that a full-focus SAR processing of Sentinel-3 radar altimeter data also reveals the presence and wavelengths of waves in sea ice, within minutes of Sentinel-2 imagery. The SWIM instrument on CFOSAT is another source of quantitative evidence for the direction and wavelengths of waves in ice, when ice conditions are spatially homogeneous. In the presence of sea ice, a quantitative wave height measurement method is not yet available for all-weather near-nadir radar instruments such as altimeters and SWIM. However, their systematic colocation with optical instruments on Sentinel-2 and ICESat-2, which are less frequently able to observe waves in sea ice, may provide the empirical transfer functions needed to interpret and calibrate the radar data, greatly expanding the available data on wave-ice interactions.","remote sensing; sea ice; wind waves","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Mathematical Geodesy and Positioning","","",""
"uuid:bd76bb1c-40f4-4bb5-9dca-eb65864a94f0","http://resolver.tudelft.nl/uuid:bd76bb1c-40f4-4bb5-9dca-eb65864a94f0","Melting Behavior of Rimed and Unrimed Snowflakes Investigated With Statistics of Triple-Frequency Doppler Radar Observations","Karrer, Markus (University of Cologne); Dias Neto, J. (TU Delft Atmospheric Remote Sensing; University of Cologne); von Terzi, Leonie (University of Cologne); Kneifel, Stefan (University of Cologne)","","2022","Comparing the reflectivity flux at the top and bottom of the melting layer (ML) reveals the overall effect of the microphysical processes occurring within the ML on the particle population. If melting is the only process taking place and all particles scatter in the Rayleigh regime, the reflectivity flux increases in the ML by a constant factor given by the ratio of the dielectric factors. Deviations from this constant factor can indicate that either growth or shrinking processes (breakup, sublimation, and evaporation) dominate. However, inference of growth or shrinking dominance from the increase in reflectivity flux is only possible if other influences (e.g., vertical wind speed) are negligible or corrected. By analyzing radar Doppler spectra and multi-frequency observations, we correct the reflectivity fluxes for vertical wind and categorize the height profiles by the riming degree at the ML top. We apply this reflectivity flux ratio (ZFR) approach to a multi-month mid-latitude winter data set that contains mostly stratiform clouds. The profiles of radar variables in the ML are found to be surprisingly similar for both unrimed and rimed profiles with slight differences, for example, in the absolute values of the reflectivity flux. Statistical analysis of the ZFR suggests that either microphysical processes other than melting are not important or strongly compensate for each other. The results seem to confirm that at least for moderately precipitating stratiform clouds, the melting-only assumption applied in several retrievals and microphysical schemes is reasonable.","melting layer; multi-frequency Doppler radar; precipitation; reflectivity flux ratio approach; remote sensing; riming","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:183e31a4-ab3f-4402-a4b2-1d25590c6acf","http://resolver.tudelft.nl/uuid:183e31a4-ab3f-4402-a4b2-1d25590c6acf","Water and productivity accounting using WA+ framework for sustainable water resources management: Case study of northwestern Iran","Ghorbanpour, Ali Karbalaye (Iran University of Science and Technology; University of California); Afshar, Abbas (Iran University of Science and Technology); Hessels, T.M. (TU Delft Water Resources); Duan, Zheng (Lund University)","","2022","An exhaustive evaluation of water resources is a prerequisite for evidence-informed planning and implementing sustainable management strategies. However, the lack of sufficient information on water supply and consumption, alongside the technical limitations on comprehensive accounting for inter-relations and interactions between the subsystems, has resulted in decisions with often long-lasting outcomes and undesirable consequences. Water accounting is a tool for systematic acquisition, analysis, and reporting of water-related information to fill the existing knowledge gap on water flows and fluxes. In this study, Water Accounting Plus (WA+) framework is applied to the western region of Lake Urmia, a dying hyper-saline lake, to assess water use and crop water productivity (CWP) from 2010 to 2016. Remotely sensed information along with a distributed hydrological model (SPHY) is used to fill the information gap on water resources and inform effective policy actions. Our analysis reveals that the agricultural sector is neither productive nor efficient while there is a considerable scope to ameliorate water productivity and beneficial water use by adopting proper water management practices. Average CWP values for wheat, sugarbeet, vineyard, and apple vary between 0.38 and 0.55, 5.1–5.6, 1.5–1.7 and 1.9–2.3 (kg/m3), respectively while storage changes show consistent depletion, especially during dry year, up to 117 MCM. The results indicate that a 40% reduction in blue water use is achievable to supply additional water to revive Lake Urmia. This study highlights the importance of water accounting and information flow for decision-makers, practitioners, and farming communities to define practical targets and enhance productivity in water-scarce regions.","Crop water productivity; Lake Urmia; Remote sensing; Sustainable management; Water accounting plus","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Water Resources","","",""
"uuid:4d05228f-4cf5-42a5-9319-f4c6fdbe4a2c","http://resolver.tudelft.nl/uuid:4d05228f-4cf5-42a5-9319-f4c6fdbe4a2c","Characterizing the thermal effects of vegetation on urban surface temperature","Yang, Jinxin (Guangzhou University); Shi, Qian (Sun Yat-sen University); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Xie, Yanhua (University of Wisconsin-Madison); Wu, Zhifeng (Guangzhou University); Xu, Yong (Guangzhou University); Abbas, Sawaid (University of Punjab)","","2022","Vegetation is important for urban heat mitigation. The cooling intensity of vegetation is affected by background climate and urban design. How to evaluate vegetation cooling efficiency under different climate conditions is still an issue open to discussion. In this study, a normalized indicator of urban vegetation cooling efficiency (NVCE) is proposed as a metric of urban vegetation cooling efficiency applicable and comparable under different climate and urban conditions. When surfaces are only covered by vegetation, the cooling effects should be highest than other pixels at the local climate scale. The difference of surface temperature between the pure vegetation surfaces and surfaces without vegetations (Tr, b − Tr, v) is the range of the vegetation cooling intensity at the same local climate conditions. Difference between radiometric surface temperature of a mixed pixel and the vegetation temperature within the mixed pixel (Ti, r − Ti, v) is excess temperature of pixel i. The ratio of (Ti, r − Ti, v) to (Tr, b − Tr, v) can indicate how much percent of existed excess temperature after vegetation cooling effects for pixel i under such local climate condition. Thus, the NVCE is defined as (Ti, r − Ti, v)/(Tr, b − Tr, v). Based on the high spatial resolution data, the Ti, v and Ti, rwithin each 30 m × 30 m grid are derived to calculate the NVCE and the relationships between NVCE and fractional vegetation cover were studied under different conditions. Results showed that NVCE can reduce the differences caused by background climate in the assessment of vegetation cooling efficiency, i.e. making vegetation cooling efficiency under different climate conditions comparable. The NVCE is also sensitive to the vegetation fraction. When vegetation fraction is smaller than 0.2, the mean value of NVCE is about 0.5 and no obvious change. This means that the vegetation has no obvious cooling effects when vegetation fraction is smaller than 0.2. When the vegetation fraction is higher than 0.2, NVCE decreases linearly with increasing vegetation fraction. When the vegetation fraction is higher than 0.9, NVCE tends to 0. This indicates that 0.2 for vegetation fraction is the threshold of vegetation cooling effects. This study can provide information for evaluating the vegetation cooling efficiency under different climate and geometric conditions. This study also can provide useful information for urban green infrastructure design and planning, e.g. the vegetation fraction should be higher than 0.2 for urban cooling and the vegetation cooling efficiency can reach maximum when SVF is about 0.5 to 0.6.","Remote sensing; Urban heat island; Vegetation cooling effects","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Optical and Laser Remote Sensing","","",""
"uuid:b5d7563d-0690-4508-914e-a75a2e7aba22","http://resolver.tudelft.nl/uuid:b5d7563d-0690-4508-914e-a75a2e7aba22","Detecting anthropogenic volume changes in cross sections of a sandy beach with permanent laser scanning","Kuschnerus, M. (TU Delft Optical and Laser Remote Sensing); Lindenbergh, R.C. (TU Delft Optical and Laser Remote Sensing); Lodder, Q.J. (TU Delft Policy Analysis; TU Delft Coastal Engineering; Ministry of Infrastructure and the Environment); Brand, E. (Ministry of Infrastructure and the Environment); Vos, S.E. (TU Delft Coastal Engineering)","","2022","Coastal areas world wide are highly dynamic areas, subject to continuous deformation processes. Both natural and anthropogenic processes constantly cause changes at various spatial scales. Sandy beaches in the Netherlands fall under a regulation, according to which moving sand is permitted, if the volume change remains below a certain threshold. The threshold holds for volume changes within a cross section of 1 m width of the beach. The enforcement of this rule is currently labor intensive, because monitoring generally happens only on a yearly basis, or incidental and non-quantitative. Improved observation capabilities with remote sensing are advancing the supporting technology for this kind of regulations. Permanent laser scanning is a potential tool for monitoring and quantifying volume changes of a section of the beach. We develop and implement methodology to extract time series of volume change with respect to a reference date of 01-01-2020 covering January 2020 until the end of April 2020. The method is applied on point cloud data from a permanent laser scanner on the coast of Noordwijk, The Netherlands. We analyse the time series for incidents, where the threshold in volume change is passed, and find all shortest intervals during which the threshold is passed. Then we analyse potential underlying cause in order to support not only enforcement, but also evaluation of the current regulation. This will ultimately help to work towards a better understanding of the influence of small scale human activities on coastal development.","Change Detection; Coastal Remote Sensing; Permanent Laser Scanning; Time Series; Volume Change","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:929b2360-2d3a-4acb-8f68-ac736c50a400","http://resolver.tudelft.nl/uuid:929b2360-2d3a-4acb-8f68-ac736c50a400","Spectropolarimetry of life: Airborne measurements from a hot air balloon","Mulder, W. (TU Delft Astrodynamics & Space Missions; Universiteit Leiden); Patty, C. H.Lucas (University of Bern); Spadaccia, Stefano (University of Bern); Pommerol, Antoine (University of Bern); Demory, Brice Olivier (University of Bern); Keller, Christoph U. (Universiteit Leiden; Lowell Observatory); Kühn, Jonas G. (University of Bern; Université de Genève); Snik, Frans (Universiteit Leiden); Stam, D.M. (TU Delft Astrodynamics & Space Missions)","Lakshminarayanan, Vasudevan (editor); Creath, Katherine (editor); Shaw, Joseph A. (editor)","2022","Does life exist outside our Solar System A first step towards searching for life outside our Solar System is detecting life on Earth by using remote sensing applications. One powerful and unambiguous biosignature is the circular polarization resulting from the homochirality of biotic molecules and systems. We aim to investigate the possibility of identifying and characterizing life on Earth by using airborne spectropolarimetric observations from a hot air balloon during our field campaign in Switzerland, May 2022. In this proceeding we present the optical-setup and the data obtained from aerial circular spectropolarimetric measurements of farmland, forests, lakes and urban sites. We make use of the well-calibrated FlyPol instrument that measures the fractionally induced circular polarization (V/I) of (reflected) light with a sensitivity of < 10-4. The instrument operates in the visible spectrum, ranging from 400 to 900 nm. We demonstrate the possibility to distinguish biotic from abiotic features using circular polarization spectra and additional broadband linear polarization information. We review the performance of our optical-setup and discuss potential improvements. This sets the requirements on how to perform future airborne spectropolarimetric measurements of the Earth's surface features from several elevations.","Biosignatures; Earth observation; Field campaign; Polarization; Remote-sensing; Spectropolarimetry","en","conference paper","SPIE","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Astrodynamics & Space Missions","","",""
"uuid:2ca42400-ed09-4010-8f3c-3050d6e4c45d","http://resolver.tudelft.nl/uuid:2ca42400-ed09-4010-8f3c-3050d6e4c45d","Perspective on satellite-based land data assimilation to estimate water cycle components in an era of advanced data availability and model sophistication","De Lannoy, Gabriëlle J.M. (Katholieke Universiteit Leuven); Bechtold, Michel (Katholieke Universiteit Leuven); Albergel, Clément (ECSAT); Brocca, Luca (IMAMOTER - C.N.R. Sensors and Nanomaterials Laboratory); Calvet, Jean Christophe (ENSIACET); Carrassi, Alberto (University of Reading; University of Bologna); Crow, Wade T. (USDA-ARS Hydrology and Remote Sensing Laboratory); de Rosnay, Patricia (European Centre for Medium Range Weather Forecasts); Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning)","","2022","The beginning of the 21st century is marked by a rapid growth of land surface satellite data and model sophistication. This offers new opportunities to estimate multiple components of the water cycle via satellite-based land data assimilation (DA) across multiple scales. By resolving more processes in land surface models and by coupling the land, the atmosphere, and other Earth system compartments, the observed information can be propagated to constrain additional unobserved variables. Furthermore, access to more satellite observations enables the direct constraint of more and more components of the water cycle that are of interest to end users. However, the finer level of detail in models and data is also often accompanied by an increase in dimensions, with more state variables, parameters, or boundary conditions to estimate, and more observations to assimilate. This requires advanced DA methods and efficient solutions. One solution is to target specific observations for assimilation based on a sensitivity study or coupling strength analysis, because not all observations are equally effective in improving subsequent forecasts of hydrological variables, weather, agricultural production, or hazards through DA. This paper offers a perspective on current and future land DA development, and suggestions to optimally exploit advances in observing and modeling systems.","data assimilation; land surface modeling; microwave remote sensing; snow; soil moisture; targeted observations; vegetation","en","review","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:88b24395-46f9-49e0-9152-cc178a32a30f","http://resolver.tudelft.nl/uuid:88b24395-46f9-49e0-9152-cc178a32a30f","An Agenda for Land Data Assimilation Priorities: Realizing the Promise of Terrestrial Water, Energy, and Vegetation Observations From Space","Kumar, Sujay (NASA Goddard Space Flight Center); Kolassa, Jana (NASA Goddard Space Flight Center; Science Systems and Applications Inc.); Reichle, Rolf (NASA Goddard Space Flight Center); Crow, Wade (USDA-ARS Hydrology and Remote Sensing Laboratory); de Lannoy, Gabrielle (Katholieke Universiteit Leuven); de Rosnay, Patricia (European Centre for Medium Range Weather Forecasts); MacBean, Natasha (University of Western Ontario); Quaife, Tristan (University of Reading); Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning)","","2022","The task of quantifying spatial and temporal variations in terrestrial water, energy, and vegetation conditions is challenging due to the significant complexity and heterogeneity of these conditions, all of which are impacted by climate change and anthropogenic activities. To address this challenge, Earth Observations (EOs) of the land and their utilization within data assimilation (DA) systems are vital. Satellite EOs are particularly relevant, as they offer quasi-global coverage, are non-intrusive, and provide uniformity, rapid measurements, and continuity. The past three decades have seen unprecedented growth in the number and variety of land remote sensing technologies launched by space agencies and commercial companies around the world. There have also been significant developments in land modeling and DA systems to provide tools that can exploit these measurements. Despite these advances, several important gaps remain in current land DA research and applications. This paper discusses these gaps, particularly in the context of using DA to improve model states for short-term numerical weather and sub-seasonal to seasonal predictions. We outline an agenda for land DA priorities so that the next generation of land DA systems will be better poised to take advantage of the significant current and anticipated shifts and advancements in remote sensing, modeling, computational technologies, and hardware resources.","data assimilation; hydrology; land surface; remote sensing","en","review","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:11649a3a-7ca6-4a89-bbf7-3383c3b818f5","http://resolver.tudelft.nl/uuid:11649a3a-7ca6-4a89-bbf7-3383c3b818f5","A critical review of discontinuity plane extraction from 3D point cloud data of rock mass surfaces","Daghigh, Hamid (University of British Columbia); Tannant, Dwayne D. (University of British Columbia); Daghigh, Vahid (Mississippi State University); Lichti, Derek D. (University of Calgary); Lindenbergh, R.C. (TU Delft Optical and Laser Remote Sensing)","","2022","Field investigations of geometric discontinuity properties in rock masses are increasingly using three-dimensional point cloud data. These point clouds sample the rock mass surface and are typically acquired by photogrammetry or LiDAR. The automatic segmentation and extraction of planar surfaces from point cloud data have attracted significant attention among researchers. This paper reviews the capabilities, merits, and limitations of different segmentation methods for discontinuity plane surface extraction and the specific challenges of processing point cloud data collected from rock faces. The segmentation and orientation results of a series of studies on two point cloud datasets of rock mass surfaces are critically discussed. A new set of ground truth orientations for one point cloud and some challenges faced while labeling a ground truth discontinuity plane are presented. Some suggestions to establish reliable and reproducible ground truth orientation results are presented. Two popular open-source software tools (CloudCompare and Discontinuity Set Extractor) for planar surface extraction are reviewed, and their capabilities and shortcomings are discussed. Acquisition of high-quality point cloud data and sharing it on a public repository establishes a basis for researchers to implement their methodologies and meaningfully compare their results to advance the knowledge in the field. Finally, some recommendations for future research and development are summarized.","Discontinuity plane extraction; LiDAR; Point cloud segmentation; Remote sensing; Rock mass; Unsupervised learning","en","review","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Optical and Laser Remote Sensing","","",""
"uuid:1cc31981-5a50-41d5-949e-5866d964fd44","http://resolver.tudelft.nl/uuid:1cc31981-5a50-41d5-949e-5866d964fd44","Bio-Remote Sensing in Predicting Infection in Neonates With Thermal Imaging and Machine Learning","Rassels, K. (TU Delft Biomechatronics & Human-Machine Control); French, P.J. (TU Delft Bio-Electronics)","","2022","Premature birth complications have different causes and vary in different parts of the world with sepsis as one of the leading causes of these complications. The body releases anti-inflammatory substances when an infection is detected and this, in turn, could damage healthy organs, especially when they are not fully developed. Preterm babies are susceptible to diseases due to their underdeveloped organs and immune systems. Hence, it is extremely important to treat sepsis as soon as the baby is diagnosed. Neonatal sepsis is a dangerous nonspecific disease in babies, and it is a clinically very difficult and challenging task to diagnose. Late or incorrect treatment of infants' sepsis can lead to death which is one of the most causes of mortality rate in neonates. In the traditional treatment of sepsis, the needed time and accuracy for diagnosis are still very concerning, considering the number of involved risks in late diagnosis or mistreatment of sepsis cases. Thus, the need for having a fast and reliable algorithm with high accuracy to predict sepsis before clinical recognition would help the doctors to treat the neonates in time and to reduce the mortality rate related to sepsis. This paper presents a fast, accurate, and reliable thermographic Bio-Remote Sensing approach to predicting sepsis in neonates and discusses the significance of combining the Thermal Imaging technique with Machine Learning (ML). At the same time, it provides a more practical and desirable solution for physicians by minimising the traditional diagnosis time and maximizing the accuracy of the prediction needed to detect sepsis in neonates.","Artificial Intelligence (AI), Machine Learning (ML), Premature babies, Incubator; Bio-Remote Sensing, Predicting Infection, Thermographic technology; Body temperature measurement; neonates; Sepsis, Infrared thermal imaging","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Biomechatronics & Human-Machine Control","","",""
"uuid:b4a931b9-d94c-49cc-b331-2a62f08a2c2e","http://resolver.tudelft.nl/uuid:b4a931b9-d94c-49cc-b331-2a62f08a2c2e","Microwave remote sensing for agricultural drought monitoring: Recent developments and challenges","Vreugdenhil, Mariette (Technische Universität Wien); Greimeister-Pfeil, Isabella (Technische Universität Wien); Preimesberger, Wolfgang (Technische Universität Wien); Camici, Stefania (CNR-IRPI); Dorigo, Wouter (Technische Universität Wien); Enenkel, Markus (Harvard University); van der Schalie, Robin (Planet Labs PBC); Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning); Wagner, Wolfgang (Technische Universität Wien)","","2022","Agricultural droughts are extreme events which are often a result of interplays between multiple hydro-meteorological processes. Therefore, assessing drought occurrence, extent, duration and intensity is complex and requires the combined use of multiple variables, such as temperature, rainfall, soil moisture (SM) and vegetation state. The benefit of using information on SM and vegetation state is that they integrate information on precipitation, temperature and evapotranspiration, making them direct indicators of plant available water and vegetation productivity. Microwave remote sensing enables the retrieval of both SM and vegetation information, and satellite-based SM and vegetation products are available operationally and free of charge on a regional or global scale and daily basis. As a result, microwave remote sensing products play an increasingly important role in drought monitoring applications. Here, we provide an overview of recent developments in using microwave remote sensing for large-scale agricultural drought monitoring. We focus on the intricacy of monitoring the complex process of drought development using multiple variables. First, we give a brief introduction on fundamental concepts of microwave remote sensing together with an overview of recent research, development and applications of drought indicators derived from microwave-based satellite SM and vegetation observations. This is followed by a more detailed overview of the current research gaps and challenges in combining microwave-based SM and vegetation measurements with hydro-meteorological data sets. The potential of using microwave remote sensing for drought monitoring is demonstrated through a case study over Senegal using multiple satellite- and model-based data sets on rainfall, SM, vegetation and combinations thereof. The case study demonstrates the added-value of microwave-based SM and vegetation observations for drought monitoring applications. Finally, we provide an outlook on potential developments and opportunities.","agriculture; drought; microwave remote sensing; soil moisture; vegetation","en","review","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:e4b484a0-fb73-4a13-a38f-d48204c5fd9b","http://resolver.tudelft.nl/uuid:e4b484a0-fb73-4a13-a38f-d48204c5fd9b","Sentinel-1 Backscatter Time Series for Characterization of Evapotranspiration Dynamics over Temperate Coniferous Forests","Mueller, Marlin M. (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); Friedrich Schiller University Jena); Dubois, Clémence (Friedrich Schiller University Jena); Jagdhuber, Thomas (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); Universität Augsburg); Hellwig, Florian M. (Friedrich Schiller University Jena; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)); Pathe, Carsten (Friedrich Schiller University Jena); Schmullius, Christiane (Friedrich Schiller University Jena); Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning)","","2022","Forests’ ecosystems are an essential part of the global carbon cycle with vast carbon storage potential. These systems are currently under external pressures showing increasing change due to climate change. A better understanding of the biophysical properties of forests is, therefore, of paramount importance for research and monitoring purposes. While there are many biophysical properties, the focus of this study is on the in-depth analysis of the connection between the C-band Copernicus Sentinel-1 SAR backscatter and evapotranspiration (ET) estimates based on in situ meteorological data and the FAO-based Penman–Monteith equation as well as the well-established global terrestrial ET product from the Terra and Aqua MODIS sensors. The analysis was performed in the Free State of Thuringia, central Germany, over coniferous forests within an area of 2452 km2, considering a 5-year time series (June 2016–July 2021) of 6- to 12-day Sentinel-1 backscatter acquisitions/observations, daily in situ meteorological measurements of four weather stations as well as an 8-day composite of ET products of the MODIS sensors. Correlation analyses of the three datasets were implemented independently for each of the microwave sensor’s acquisition parameters, ascending and descending overpass direction and co- or cross-polarization, investigating different time series seasonality filters. The Sentinel-1 backscatter and both ET time series datasets show a similar multiannual seasonally fluctuating behavior with increasing values in the spring, peaks in the summer, decreases in the autumn and troughs in the winter months. The backscatter difference between summer and winter reaches over 1.5 dB, while the evapotranspiration difference reaches 8 mm/day for the in situ measurements and 300 kg/m2/8-day for the MODIS product. The best correlation between the Sentinel-1 backscatter and both ET products is achieved in the ascending overpass direction, with datasets acquired in the late afternoon, and reaches an R2-value of over 0.8. The correlation for the descending overpass direction reaches values of up to 0.6. These results suggest that the SAR backscatter signal of coniferous forests is sensitive to the biophysical property evapotranspiration under some scenarios.","backscatter; coniferous forests; evapotranspiration; MODIS; remote sensing; SAR; Sentinel-1; single spectrum analysis; thuringia; time series","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:2003d80c-4305-4f26-bc6c-d027533cbb1a","http://resolver.tudelft.nl/uuid:2003d80c-4305-4f26-bc6c-d027533cbb1a","Uncertainty in Satellite Remote Sensing Derived Evapotranspiration Estimation: Current Status and Assessment Methods","Tran, N.B. (TU Delft Water Resources; IHE Delft Institute for Water Education); Van Der Kwast, Johannes (IHE Delft Institute for Water Education); Mul, Marloes (IHE Delft Institute for Water Education); Seyoum, S.D. (TU Delft Water Resources; IHE Delft Institute for Water Education); Uijlenhoet, R. (TU Delft Water Resources); Jewitt, G.P.W. (TU Delft Water Resources; IHE Delft Institute for Water Education)","Ortega-Sánchez, Miguel (editor)","2022","Evapotranspiration (ET), a key variable in both water and energy cycles. It is very challenging to measure or estimate in large regions. Among many approaches to estimate ET indirectly (e.g. through hydrological modelling), models that are based on satellite remote sensing data (RS) are increasingly being used. However, the RS-based models inherit uncertainty from many sources, such as the model’s algorithm and parameters, input satellite data, and processing techniques. It is challenging to assess this uncertainty due to limitations of validation data, high volume and high dimensionality of RS data. Many studies have evaluated uncertainty in RS-based estimation of ET using different methods and reference data. The suitability of methods and reference data subsequently affect the validity of these evaluations. Therefore, it is necessary to have an overview of different evaluation methods and their uses. This study aimed to systematically review original research papers that assessed uncertainty or accuracy of RS-ET model or data products. We categorized these papers and quantified based on (i) spatial and temporal scale of ET estimation, (ii) types of uncertainty, and (iii) methods used to assess uncertainty. Studies have been geographically concentrated in North Asia, North America, and Europe. Most studies used the validation method, which quantifies the discrepancy between pixel-based ET estimation with an in-situ estimation. Although a standardized validation approach for satellite-based ET estimates is not yet ready, most validation studies employed Eddy Covariance (EC) flux towers for reference estimation at field-scale. In regions where in-situ measurements are limited, many studies use the residual of the water balance as reference. However, few studies considered uncertainty in the reference estimation and mismatch of spatial and temporal scales. For monitoring agricultural fields, most RS-ET methods have been reported with high accuracy. When applying these methods to larger extent, additional assessments are required to better inform data users of the quality of RS-ET estimation. These include cross-validation, sensitivity, and uncertainty analyses. Overall, this review showed the progress in evapotranspiration estimation using satellite data in terms of uncertainty assessment.","Evapotranspiration; Remote sensing; Satellite data; Surface energy balance models; Uncertainty","en","conference paper","IAHR","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-12-24","","","Water Resources","","",""
"uuid:257afeb8-49db-495e-a786-9d73bf4d9906","http://resolver.tudelft.nl/uuid:257afeb8-49db-495e-a786-9d73bf4d9906","Surveying and Mapping","Tiberius, C.C.J.M. (TU Delft Mathematical Geodesy and Positioning); van der Marel, H. (TU Delft Mathematical Geodesy and Positioning); Reudink, R.H.C. (TU Delft Laboratory Geoscience and Remote Sensing); van Leijen, F.J. (TU Delft Mathematical Geodesy and Positioning)","","2022","This book provides an introduction, at academic level, into the field of surveying and mapping. The book has been compiled based on hand-outs and readers written for the third-year course Surveying and Mapping, in the bachelor program Civil Engineering at Delft University of Technology. This book covers a wide range of measurement techniques, from land surveying, GPS/GNSS and remote sensing to the associated data processing, the underlying coordinate reference systems, as well as the analysis and visualization of the acquired geospatial information.","land surveying; mathematical geodesy; GPS; remote sensing; reference systems; mapping","en","book","TU Delft OPEN","9789463664905","","","","TU Delft OPEN Textbook","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:3404c498-f317-4ce2-8d85-9dba4fb1e353","http://resolver.tudelft.nl/uuid:3404c498-f317-4ce2-8d85-9dba4fb1e353","Identifying downstream gains from local losses: A new set of methods for tracking water reuse across river basins","Simons, G.W.H. (TU Delft Water Resources)","Bastiaanssen, W.G.M. (promotor); Immerzeel, Walter W. (promotor); Delft University of Technology (degree granting institution)","2021","Downstream reuse of previously withdrawn water resources is a common phenomenon across river basins worldwide, particularly those with (semi-)arid climate conditions and intensive water resources development. Water reuse often occurs unplanned, remains undetected, and as a result is insufficiently considered in water saving attempts, water allocation strategies, and water rights and pricing systems. This has led to a long list of ineffective and counter-productive introductions of Water Saving Technologies and Practices (WSTPs), with significant economic, social, and environmental consequences. Awareness of indirect water reuse has increased in recent years, both in integrated river basin management as well as in the irrigation sector, which has traditionally been focused on enhancing irrigation efficiencies. However, accounting for water reuse in decision-making has remained limited due to problematic terminology, scarcity of data, and a general lack of methods and tools for explicit assessment of water reuse across hydrological systems.
This research aims to address these problems by developing a coherent set of methods for spatiotemporal evaluation of water reuse. This dissertation presents and demonstrates an appropriate framework of concepts and indicators, as well as a number of complementary procedures for quantifying these indicators based on innovative data sources and newly developed algorithms.","water reuse; remote sensing; water accounting; water saving","en","doctoral thesis","","","","","","","","","","","Water Resources","","",""
"uuid:09d84cc1-27e2-4327-a8c7-207a75952061","http://resolver.tudelft.nl/uuid:09d84cc1-27e2-4327-a8c7-207a75952061","Internal processes in hydrological models: A glance at the Meuse basin from space","Bouaziz, L.J.E. (TU Delft Water Resources)","Hrachowitz, M. (promotor); Savenije, Hubert (promotor); Delft University of Technology (degree granting institution)","2021","Contemplating the Meuse or any other river of the world, one may wonder about the journey of rain in becoming river. This fascinates hydrologists, as they develop theories to understand movement, storage and release of water through the landscape across climates. These theories are translated to hydrological models, which describe the complex reality in a simpler way. Models are then used to predict the hydrological cycle for the nearby or long-term future. This thesis aims to assist the Dutch Ministry of Infrastructure and Water Management in improving the reliability of hydrological modeling of the Meuse basin for operational and policy applications. Using in-situ and remote-sensing data, the value of representing additional processes in models is explored, as well as the creative use of additional data to improve hydrological predictions. First, water balance data is used to identify the potential presence of intercatchment groundwater flows (Chapter 3). These underground flow paths cross topographic catchment boundaries and mainly play a role in headwater catchments (< 500 km2) of the Meuse basin, which are underlain by productive aquifers. Representing this flux as a preferential threshold-initiated process improves low and high flow model performance and increases the consistency between modeled and remote-sensing estimates of actual evaporation. Besides the importance of quantifying the long-term hydrological partitioning of precipitation into streamflow, evaporation and potentially intercatchment groundwater flows, another key element of the hydrological response is the amount of water available in the root-zone of vegetation. The temporal dynamics of root-zone soil moisture control how much more water can be stored in the soil and how much water is available for transpiration. In Chapter 4, meaningful estimates of root-zone soil moisture are inferred from satellite observations of near-surface soil moisture, by establishing a link between the catchment-scale root-zone storage capacity and the Soil Water Index. Interestingly, hydrological models with different internal process representations of root-zone soil moisture, evaporation, snow and total storage at the catchment scale may lead to a similar aggregated streamflow response (Chapter 5). This discrepancy implies that models are not necessarily providing the right answers for the right reasons, as they cannot simultaneously be close to reality and different from each other. To circumvent the uncertainty of process representation, which is inherent to hydrological science, the use of multiple model structures is advocated for operational and policy applications. Nonetheless, testing the consistency between modeled hydrological behavior and independent remote-sensing data can foster model developments and lead to creating better models. Finally, we move beyond the use of historical in-situ and remote-sensing data to predict long-term hydrological behavior of the Meuse basin under projected global warming (Chapter 6). If environmental conditions change, it is likely to also assume ecosystem adaptation in response to climate change and a potential natural and/or anthropogenic shift in dominant species across the landscape. Non-stationarity in the representation of hydrological systems is introduced in a process-based model with three hydrological response units to account for the spatial variability of hydrological processes. More specifically, we adapt the root-zone storage capacity parameter using the information contained in the projected climate data. This is an important step forward in the great challenge of hydrological predictions under change. Despite data uncertainties and a lack of data at the required temporal and spatial resolutions, many possibilities are at hand with what is currently available to develop new theories, test and improve hydrological models. Requiring creativity, this is a beautiful challenge to further unravel the mysteries of the hydrological landscape.","hydrological modeling; Meuse basin; root-zone storage capacity; remote sensing; states and fluxes; intercatchment groundwater flow; Climate change; Soil Water Index","en","doctoral thesis","","978-94-6421-419-2","","","","","","","","","Water Resources","","",""
"uuid:42c5bef9-8195-42a5-a103-49b8bbbc2d96","http://resolver.tudelft.nl/uuid:42c5bef9-8195-42a5-a103-49b8bbbc2d96","Monitoring Aerosol Cloud Interactions in Liquid Water Clouds","Sarna, K. (TU Delft Atmospheric Remote Sensing)","Russchenberg, H.W.J. (promotor); Delft University of Technology (degree granting institution)","2021","This thesis presents a new method for the continuous observation of aerosol-cloud interactions with ground-based remote sensing instruments. The described method is based on the measurements from UV lidar, radar and radiometer. All of those instruments are capable of obtaining continuous, high-resolution measurements. In order to facilitate its easy implementation to measuring sites the method is based on a standardized Cloudnet data format. The main goal is to monitor the change in the cloud droplet concentration, as obtained from the measurements by cloud radar and radiometer, to then compare it to the aerosol background below the cloud, represented by the attenuated backscatter measured by UV lidar. The response of the cloud to the aerosol background can best be measured when the amount of available water is kept constant. Hence the measurements from the radiometer, specifically the derived liquid water path (LWP), which is used to constrain the cloud response. Based on the value of the LWP, analyzed data is divided into bins and for each of these the relation between cloud droplet effective radius and integrated value of the attenuated backscatter are calculated. This metric is called ACIr and is used to describe the strength of the relation between the clouds microphysical properties and the aerosol background below the cloud.
The method was first tested and applied to pristine marine clouds as measured at the Graciosa Island in the Azores. The application was then extended to the Cabauw site located in the Netherlands. On both sites a decrease in the cloud size was observed in combination with a simultaneous increase of the aerosol loading below the cloud. This relation was particularly strong for a mid range of the LWP, between 40 and 60 gm-2 LWP for the cases from Azores and between 60 and 105 gm-2 for the cases from the Netherlands. These results indicate that the process of aerosol-cloud interactions is a predominant one only under those conditions where a mid amount of water is available. When the amount of available water is less than 40 gm-2 this process is harder to observe, due to the initial stage of cloud formation. In the case of LWP above 105 gm-2 other cloud processes, such as collision and coalescence, seem to be predominant. The results from the analysis of the Cabauw dataset, which was the more extensive dataset, also made clear that updraft within the cloud plays a significant role in invigorating aerosol particles into becoming cloud droplets. A possible extension of the presented method includes obtaining optical cloud extinction from the UV lidar measurements. The presented retrieval method can obtain very reliable results when compared to the simulated results. Hence the cloud optical extinction can be used as a proxy of the cloud properties and the described method of monitoring aerosol-cloud interactions can be applied to measurement sites where only UV lidar and radiometer are present. This thesis shows that ground-based remote sensing instruments used in synergy can efficiently and continuously monitor aerosol–cloud interactions.","aerosol; clouds; aerosolclouds interactions; remote sensing","en","doctoral thesis","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:97a7173b-051b-4521-9af1-5113ab13d8d4","http://resolver.tudelft.nl/uuid:97a7173b-051b-4521-9af1-5113ab13d8d4","Multi-Source Hydrological Data Products to Monitor High Asian River Basins and Regional Water Security","Menenti, M. (TU Delft Optical and Laser Remote Sensing); Li, Xin (Chinese Academy of Sciences); Jia, Li (Chinese Academy of Sciences); Yang, Kun (Tsinghua University); Pellicciotti, Francesca (Swiss Federal Institute for Forest, Snow and Landscape Research); Mancini, Marco (Politecnico di Milano); Shi, Jiancheng (Chinese Academy of Sciences); Escorihuela, Maria José (IsardSAT); Zheng, Chaolei (Chinese Academy of Sciences)","","2021","This project explored the integrated use of satellite, ground observations and hydrological distributed models to support water resources assessment and monitoring in High Mountain Asia (HMA). Hydrological data products were generated taking advantage of the synergies of European and Chinese data assets and space-borne observation systems. Energy-budget-based glacier mass balance and hydrological models driven by satellite observations were developed. These models can be applied to describe glacier-melt contribution to river flow. Satellite hydrological data products were used for forcing, calibration, validation and data assimilation in distributed river basin models. A pilot study was carried out on the Red River basin. Multiple hydrological data products were generated using the data collected by Chinese satellites. A new Evapo-Transpiration (ET) dataset from 2000 to 2018 was generated, including plant transpiration, soil evaporation, rainfall interception loss, snow/ice sublimation and open water evaporation. Higher resolution data were used to characterize glaciers and their response to environmental forcing. These studies focused on the Parlung Zangbo Basin, where glacier facies were mapped with GaoFeng (GF), Sentinal-2/Multi-Spectral Imager (S2/MSI) and Landsat8/Operational Land Imager (L8/OLI) data. The geodetic mass balance was estimated between 2000 and 2017 with Zi-Yuan (ZY)-3 Stereo Images and the SRTM DEM. Surface velocity was studied with Landsat5/Thematic Mapper (L5/TM), L8/OLI and S2/MSI data over the period 2013–2019. An updated method was developed to improve the retrieval of glacier albedo by correcting glacier reflectance for anisotropy, and a new dataset on glacier albedo was generated for the period 2001–2020. A detailed glacier energy and mass balance model was developed with the support of field experiments at the Parlung No. 4 Glacier and the 24 K Glacier, both in the Tibetan Plateau. Besides meteorological measurements, the field experiments included glaciological and hydrological measurements. The energy balance model was formulated in terms of enthalpy for easier treatment of water phase transitions. The model was applied to assess the spatial variability in glacier melt. In the Parlung No. 4 Glacier, the accumulated glacier melt was between 1.5 and 2.5 m w.e. in the accumulation zone and between 4.5 and 6.0 m w.e. in the ablation zone, reaching 6.5 m w.e. at the terminus. The seasonality in the glacier mass balance was observed by combining intensive field campaigns with continuous automatic observations. The linkage of the glacier and snowpack mass balance with water resources in a river basin was analyzed in the Chiese (Italy) and Heihe (China) basins by developing and applying integrated hydrological models using satellite retrievals in multiple ways. The model FEST-WEB was calibrated using retrievals of Land Surface Temperature (LST) to map soil hydrological properties. A watershed model was developed by coupling ecohydrological and socioeconomic systems. Integrated modeling is supported by an updated and parallelized data assimilation system. The latter exploits retrievals of brightness temperature (Advanced Microwave Scanning Radiometer, AMSR), LST (Moderate Resolution Imaging Spectroradiometer, MODIS), precipitation (Tropical Rainfall Measuring Mission (TRMM) and FengYun (FY)-2D) and in-situ measurements. In the case study on the Red River Basin, a new algorithm has been applied to disaggregate the SMOS (Soil Moisture and Ocean Salinity) soil moisture retrievals by making use of the correlation between evaporative fraction and soil moisture.","High Mountain Asia; Data assimilation; Model calibration; Energy and water balance; Distributed hydrological models; Multispectral remote sensing","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:ad190e6d-0aa9-4422-a30f-a9c6ea8e91d0","http://resolver.tudelft.nl/uuid:ad190e6d-0aa9-4422-a30f-a9c6ea8e91d0","Can Radar Remote Life Sensing Technology Help Combat COVID-19?","Islam, Shekh M. M. (University of Hawaii at Manoa; University of Dhaka); Fioranelli, F. (TU Delft Microwave Sensing, Signals & Systems); Lubecke, Victor M. (University of Hawaii at Manoa)","","2021","COVID-19, caused by SARS-CoV-2, is now a global pandemic disease. This outbreak has affected every aspect of life including work, leisure, and interaction with technology. Governments around the world have issued orders for travel bans, social distancing, and lockdown to control the spread of the virus and prevent strain on hospitals. This paper explores potential applications for radar-based non-contact remote respiration sensing technology that may help to combat the COVID-19 pandemic, and outlines potential advantages that may also help to reduce the spread of the virus. Applications arising from recent developments in the state of the art for transceiver and signal processing
technologies will be discussed along associated technical implications. These
applications include remote breathing rate monitoring, continuous identity
authentication, occupancy detection, and hand gesture recognition. This paper also highlights future research directions that must be explored further to bring this innovative non-contact sensor technology into real-world implementation.","radar remote sensing; identity authentication; gesture recognition; occupancy sensing; breathing","en","review","","","","","","","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:88a08f1c-eaa6-4c78-ad15-104e3476ffb6","http://resolver.tudelft.nl/uuid:88a08f1c-eaa6-4c78-ad15-104e3476ffb6","Documenting Impacts of Hydro-Meteorological Events Using Earth Observation","Alfieri, S.M. (TU Delft Optical and Laser Remote Sensing); Foroughnia, Fatemeh (TU Delft Geo-engineering); van Natijne, A.L. (TU Delft Optical and Laser Remote Sensing); Mousivand, A. (TU Delft Optical and Laser Remote Sensing); Lindenbergh, R.C. (TU Delft Optical and Laser Remote Sensing); Porcu, Federico (University of Bologna); Zieher, Thomas (Austrian Academy of Sciences); Pulvirulenti, Beatrice (University of Bologna); Yang, Jingxin (Guangzhou University); Menenti, M. (TU Delft Optical and Laser Remote Sensing)","","2021","The ambition of H2020 OPERANDUM project is to develop and document Nature Based Solutions (NBS) to mitigate risks associated with hydro-meteorological (HM) hazards. NBS mitigate risks by reducing the vulnerability of a particular system. The aim of this work is to demonstrate the use of multisource remote sensing data in documenting the impact of extreme HM events to advance knowledge on vulnerability and exposure. In particular the focus is to document past impacts due to extreme events selected from a characterization of recent (3 0 years) HM events in 11 Open Air Laboratories (OALs) where co-design, co-development and deployment of NBS are taking place. The impacts were documented by applying a wide spectrum of satellite image data and other, close - range, remote sensing techniques. A better understanding of the consequences due to extreme HM events in a particular area (OALs) is essential to identify elements at risk and expected to provide a reference to evaluate the reduction of vulnerability and mitigation of risks past the completion of NBS.","Hazards; Risks; Impacts; Optical and SAR remote sensing; Sentinel","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-04-12","","","Optical and Laser Remote Sensing","","",""
"uuid:6575b91a-7e1f-419a-8038-9f8c1e78b161","http://resolver.tudelft.nl/uuid:6575b91a-7e1f-419a-8038-9f8c1e78b161","Integrated Monitoring of a Slowly Moving Landslide Based on Total Station Measurements, Multi-Temporal Terrestrial Laser Scanning and Space-Borne Interferometric Synthetic Aperture Radar","Zieher, Thomas (Austrian Academy of Sciences); Pfeiffer, Jan (Austrian Academy of Sciences); van Natijne, A.L. (TU Delft Optical and Laser Remote Sensing); Lindenbergh, R.C. (TU Delft Optical and Laser Remote Sensing)","","2021","Continuous landslide monitoring is a crucial task for the management of natural hazards for identifying suitable mitigation measures, including nature-based solutions. In the present study, three monitoring techniques including (i) an automated tracking total station (ATTS), (ii) multi-temporal terrestrial laser scanning (TLS) and (iii) space-borne interferometric synthetic aperture radar (InSAR) are applied to monitor the spatio-temporal displacement patterns of the Vögelsberg landslide (Tyrol, Austria) between 2016/05 and 2020/06. The landslide shows spatially and temporally varying displacement rates with up to 12 cm/a and a mean annual displacement of 4 cm/a. The results show that only the ATTS provides sufficient temporal resolution and spatial accuracy for assessing the temporal behaviour of the landslide's movement. However, ATTS measurements are only available at the installed 53 retro-reflecting prisms. Multi-temporal TLS can provide additional insight into the spatial displacement pattern at various man-made and natural objects such as walls, fences, poles and tree stems. But the respective accuracy and data acquisition intervals do not allow to draw conclusions about the temporal dynamics of the landslide's movement. Results of the InSAR technique based on Sentinel-1 imagery show good agreement with ATTS measurements, but cannot provide real-time information on the landslide's acceleration and deceleration phases. However, in combination, the measurement techniques provide vital information in both the spatial and temporal domain.","Deep-seated landslide; remote sensing; displacement monitoring; spatio-temporal analyses; OPERANDUM","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-04-12","","","Optical and Laser Remote Sensing","","",""
"uuid:d8139466-fa73-45b0-86fc-88dced522552","http://resolver.tudelft.nl/uuid:d8139466-fa73-45b0-86fc-88dced522552","Estimation of Potential Soil Erosion and Sediment Yield: A Case Study of the Transboundary Chenab River Catchment","Ali, Muhammad Gufran (University of Agriculture, Faisalabad); Ali, Sikandar (University of Agriculture, Faisalabad); Arshad, Rao Husnain (University of Agriculture, Faisalabad); Nazeer, A. (TU Delft Water Resources; Bahauddin Zakariya University); Waqas, Muhammad Mohsin (Khwaja Fareed University of Engineering and Information Technology); Waseem, Muhammad (Ghulam Ishaq Khan Institute of Engineering Sciences and Technology); Aslam, Rana Ammar (University of Agriculture, Faisalabad); Cheema, Muhammad Jehanzeb Masud (PMAS Arid Agriculture University); Leta, Megersa Kebede (University of Rostock, Rostock); Shauket, Imran (University of Agriculture, Faisalabad)","","2021","Near real-time estimation of soil loss from river catchments is crucial for minimizing environmental degradation of complex river basins. The Chenab river is one of the most complex river basins of the world and is facing severe soil loss due to extreme hydrometeorological conditions, unpredictable hydrologic response, and complex orography. Resultantly, huge soil erosion and sediment yield (SY) not only cause irreversible environmental degradation in the Chenab river catchment but also deteriorate the downstream water resources. In this study, potential soil erosion (PSE) is estimated from the transboundary Chenab river catchment using the Revised Universal Soil Loss Equation (RUSLE), coupled with remote sensing (RS) and geographic information system (GIS). Land Use of the European Space Agency (ESA), Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) data, and world soil map of Food and Agriculture Organization (FAO)/The United Nations Educational, Scientific and Cultural Organization were incorporated into the study. The SY was estimated on monthly, quarterly, seasonal, and annual time-scales using sediment delivery ratio (SDR) estimated through the area, slope, and curve number (CN)-based approaches. The 30-year average PSE from the Chenab river catchment was estimated as 177.8, 61.5, 310.3, 39.5, 26.9, 47.1, and 99.1 tons/ha for annual, rabi, kharif, fall, winter, spring, and summer time scales, respectively. The 30-year average annual SY from the Chenab river catchment was estimated as 4.086, 6.163, and 7.502 million tons based on area, slope, and CN approaches. The time series trends analysis of SY indicated an increase of 0.0895, 0.1387, and 0.1698 million tons per year for area, slope, and CN-based approaches, respectively. It is recommended that the areas, except for slight erosion intensity, should be focused on framing strategies for control and mitigation of soil erosion in the Chenab river catchment.","RUSLE; soil erosion; sediment yield; Chenab river; remote sensing; GIS","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:81ab62ea-ee1f-444d-9b75-120169b58169","http://resolver.tudelft.nl/uuid:81ab62ea-ee1f-444d-9b75-120169b58169","InCorr: Interactive Data-Driven Correlation Panels for Digital Outcrop Analysis","Ortner, Thomas (VRVis Research Center); Walch, Andreas (VRVis Research Center); Nowak, Rebecca (VRVis Research Center); Barnes, Robert (Imperial College London); Höllt, T. (TU Delft Computer Graphics and Visualisation); Groller, Eduard (Technische Universität Wien)","","2021","Geological analysis of 3D Digital Outcrop Models (DOMs) for reconstruction of ancient habitable environments is a key aspect of the upcoming ESA ExoMars 2022 Rosalind Franklin Rover and the NASA 2020 Rover Perseverance missions in seeking signs of past life on Mars. Geologists measure and interpret 3D DOMs, create sedimentary logs and combine them in ‘correlation panels’ to map the extents of key geological horizons, and build a stratigraphic model to understand their position in the ancient landscape. Currently, the creation of correlation panels is completely manual and therefore time-consuming, and inflexible. With InCorr we present a visualization solution that encompasses a 3D logging tool and an interactive data-driven correlation panel that evolves with the stratigraphic analysis. For the creation of InCorr we closely cooperated with leading planetary geologists in the form of a design study. We verify our results by recreating an existing correlation analysis with InCorr and validate our correlation panel against a manually created illustration. Further, we conducted a user-study with a wider circle of geologists. Our evaluation shows that InCorr efficiently supports the domain experts in tackling their research questions and that it has the potential to significantly impact how geologists work with digital outcrop representations in general.","Geographic / geospatial visualization; digital outcrop analysis; integration of spatial and non-spatial data visualization; remote sensing geology","en","journal article","","","","","","","","","","","Computer Graphics and Visualisation","","",""
"uuid:7ead3d6c-bfcc-47fa-b161-ad4c12d3969c","http://resolver.tudelft.nl/uuid:7ead3d6c-bfcc-47fa-b161-ad4c12d3969c","Detecting forest response to droughts with global observations of vegetation water content","Konings, Alexandra G. (Stanford University); Saatchi, Sassan S. (California Institute of Technology); Frankenberg, Christian (California Institute of Technology); Keller, Michael (California Institute of Technology; United States Forest Service); Leshyk, Victor (Northern Arizona University); Anderegg, William R.L. (University of Utah); Humphrey, Vincent (California Institute of Technology); Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning); Wang, Yujie (California Institute of Technology)","","2021","Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analog of the pressure–volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions—which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.","drought response; drought-induced tree mortality; microwave remote sensing; pressure–volume; vegetation optical depth; vegetation water content; water potential","en","review","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:61269165-ba8c-44bf-9fbd-e2d855e10dc1","http://resolver.tudelft.nl/uuid:61269165-ba8c-44bf-9fbd-e2d855e10dc1","Remote sensing-based automatic detection of shoreline position: A case study in apulia region","Spinosa, A. (TU Delft Mathematical Physics; Deltares); Ziemba, A.M. (TU Delft Mathematical Physics; Deltares); Saponieri, Alessandra (University of Salento); Damiani, Leonardo (Polytechnic University of Bari); El Serafy, G.Y.H. (TU Delft Mathematical Physics; Deltares)","","2021","Remote sensing and satellite imagery have become commonplace in efforts to monitor and model various biological and physical characteristics of the Earth. The land/water interface is a continually evolving landscape of high scientific and societal interest, making the mapping and monitoring thereof particularly important. This paper aims at describing a new automated method of shoreline position detection through the utilization of Synthetic Aperture Radar (SAR) images derived from European Space Agency satellites, specifically the operational SENTINEL Series. The resultant delineated shorelines are validated against those derived from video monitoring systems and in situ monitoring; a mean distance of 1 and a maximum of 3.5 pixels is found.","Coastal monitoring; Copernicus; Remote sensing; SAR; Shoreline detection","en","journal article","","","","","","","","","","","Mathematical Physics","","",""
"uuid:5b898ad7-c6d7-480e-b499-48d757020d40","http://resolver.tudelft.nl/uuid:5b898ad7-c6d7-480e-b499-48d757020d40","Tropical rainfall monitoring with commercial microwave links in Sri Lanka","Overeem, A. (Royal Netherlands Meteorological Institute (KNMI); Wageningen University & Research); Leijnse, Hidde (Royal Netherlands Meteorological Institute (KNMI); Wageningen University & Research); van Leth, Thomas C. (Wageningen University & Research); Bogerd, Linda (Royal Netherlands Meteorological Institute (KNMI); Wageningen University & Research); Priebe, Jan (GSM Association); Tricarico, Daniele (GSM Association); Droste, Arjan (Wageningen University & Research); Uijlenhoet, R. (TU Delft Water Resources; Wageningen University & Research)","","2021","Commercial microwave links (CMLs) from cellular telecommunication networks can provide a valuable 'opportunistic' source of high-resolution space-time rainfall information, complementing traditional in-situ measurement devices (rain gauges, disdrometers) and remote sensors (weather radars, satellites). Their greatest potential lies in areas with low gauge densities and lack of weather radars, often in developing countries with a subtropical or tropical climate and generally large spatial rainfall variability. Here, the open-source R package RAINLINK is employed to retrieve CML rainfall maps covering the majority of Sri Lanka for a 3.5 month period based on CML data from on average 1140 link paths. These are compared locally to hourly and daily rain gauge data, as well as to rainfall maps from the dual-frequency precipitation radar on board the global precipitation measurement core observatory satellite. The potential of CMLs for real-time tropical rainfall monitoring is demonstrated.","Commercial microwave links; Global precipitation measurement mission; Hydrometeorology; Opportunistic sensing; Rainfall monitoring; Remote sensing","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:45acfab2-ca8d-4ac1-a284-5d1a2608cb81","http://resolver.tudelft.nl/uuid:45acfab2-ca8d-4ac1-a284-5d1a2608cb81","GRACEfully Closing the Water Balance: A Data-Driven Probabilistic Approach Applied to River Basins in Iran","Schoups, G.H.W. (TU Delft Water Resources); Nasseri, M. (TU Delft Water Resources; University of Tehran)","","2021","To fully benefit from remotely sensed observations of the terrestrial water cycle, bias and random errors in these data sets need to be quantified. This paper presents a Bayesian hierarchical model that fuses monthly water balance data and estimates the corresponding data errors and error-corrected water balance components (precipitation, evaporation, river discharge, and water storage). The model combines monthly basin-scale water balance constraints with probabilistic data error models for each water balance variable. Each data error model includes parameters that are in turn treated as unknown random variables to reflect uncertainty in the errors. Errors in precipitation and evaporation data are parameterized as a function of multiple data sources, while errors in GRACE storage observations are described by a noisy sine wave model with parameters controlling the phase, amplitude, and randomness of the sine wave. Error parameters and water balance variables are estimated using a combination of Markov Chain Monte Carlo sampling and iterative smoothing. Application to semiarid river basins in Iran yields (a) significant reductions in evaporation uncertainty during water-stressed summers, (b) basin-specific timing and amplitude corrections of the GRACE water storage dynamics, and (c) posterior water balance estimates with average standard errors of 4–12 mm/month for water storage, 3.5–7 mm/month for precipitation, 2–6 mm/month for evaporation, and 0–2 mm/month for river discharge. The approach is readily extended to other data sets and other (gauged) basins around the world, possibly using customized data error models. The resulting error-filtered and bias-corrected water balance estimates can be used to evaluate hydrological models.","data errors; groundtruth; Kalman smoothing; Markov Chain Monte Carlo; remote sensing","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:1ef7d3c5-070a-4158-a848-d452621e6fd0","http://resolver.tudelft.nl/uuid:1ef7d3c5-070a-4158-a848-d452621e6fd0","A comprehensive five-year evaluation of IMERG late run precipitation estimates over the Netherlands","Bogerd, Linda (Wageningen University & Research; Royal Netherlands Meteorological Institute (KNMI)); Overeem, Aart (Wageningen University & Research; Royal Netherlands Meteorological Institute (KNMI)); Leijnse, Hidde (Wageningen University & Research; Royal Netherlands Meteorological Institute (KNMI)); Uijlenhoet, R. (TU Delft Water Resources; Wageningen University & Research)","","2021","Applications like drought monitoring and forecasting can profit from the global and near-real-time availability of satellite-based precipitation estimates once their related uncertainties and challenges are identified and treated. To this end, this study evaluates the IMERG V06B Late Run precipitation product from the Global Precipitation Measurement mission (GPM), a multisatellite product that combines space-based radar, passive microwave (PMW), and infrared (IR) data into gridded precipitation estimates. The evaluation is performed on the spatiotemporal resolution of IMERG (0.1° × 0.1°, 30 min) over the Netherlands over a 5-yr period. A gauge-adjusted radar precipitation product from the Royal NetherlandsMeteorological Institute (KNMI) is used as reference, against which IMERG shows a large positive bias. To find the origin of this systematic overestimation, the data are divided into seasons, rainfall intensity ranges, echo top height (ETH) ranges, and categories based on the relative contributions of IR, morphing, and PMW data to the IMERG estimates. Furthermore, the specific radiometer is identified for each PMW-based estimate. IMERG’s detection performance improves with higher ETH and rainfall intensity, but the associated error and relative bias increase as well. Severe overestimation occurs during low-intensity rainfall events and is especially linked to PMW observations. All individual PMW instruments show the same pattern: overestimation of low-intensity events and underestimation of high-intensity events. IMERG misses a large fraction of shallow rainfall events, which is amplified when IR data are included. Space-based retrieval of shallow and low-intensity precipitation events should improve before IMERG can become accurate over the middle and high latitudes.","Precipitation; Radars/radar observations; Rainfall; Remote sensing; Satellite observations","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2021-12-28","","","Water Resources","","",""
"uuid:44af0c88-66c7-47fe-9dbc-08241799ab40","http://resolver.tudelft.nl/uuid:44af0c88-66c7-47fe-9dbc-08241799ab40","Rainfall-induced attenuation correction for two operational dual-polarization c-band radars in the Netherlands","Overeem, A. (Royal Netherlands Meteorological Institute (KNMI); Wageningen University & Research); de Vries, Hylke (Royal Netherlands Meteorological Institute (KNMI)); Sakka, Hassan Al (Leonardo Germany GmbH); Uijlenhoet, R. (TU Delft Water Resources; Wageningen University & Research); Leijnse, Hidde (Royal Netherlands Meteorological Institute (KNMI); Wageningen University & Research)","","2021","The Royal Netherlands Meteorological Institute (KNMI) operates two operational dual-polarization C-band weather radars providing 2D radar rainfall products. Attenuation can result in severe underestimation of rainfall amounts, particularly in convective situations that are known to have high impact on society. To improve the radar-based precipitation estimates, two attenuation correction methods are evaluated and compared: 1) modified Kraemer (MK) method, i.e., Hitschfeld–Bordan where parameters of the power-law Zh–kh relation are adjusted such that reflectivities in the entire dataset do not exceed 59 dBZh and attenuation correction is limited to 10 dB; and 2) using two-way path-inte-grated attenuation computed from the dual-polarization moment specific differential phase Kdp (Kdp method). In both cases the open-source Python library wradlib is employed for the actual attenuation correction. A radar voxel only con-tributes to the computed path-integrated attenuation if its height is below the forecasted freezing-level height from the numerical weather prediction model HARMONIE-AROME. The methods are effective in improving hourly and daily quantitative precipitation estimation (QPE), where the Kdp method performs best. The verification against rain gauge data shows that the underestimation diminishes from 55% to 37% for hourly rainfall for the Kdp method when the gauge indicates more than 10 mm of rain in that hour. The improvement for the MK method is less pronounced, with a resulting underestimation of 40%. The stability of the MK method holds a promise for application to data archives from single-polarization radars.","Precipitation; Radars/Radar observations; Rainfall; Remote sensing","en","journal article","","","","","","","","2021-12-08","","","Water Resources","","",""
"uuid:624d5a9d-1bc9-4e34-bdc2-eaaae9c64074","http://resolver.tudelft.nl/uuid:624d5a9d-1bc9-4e34-bdc2-eaaae9c64074","River Flood Detection Using Passive Microwave Remote Sensing in a Data-Scarce Environment: A Case Study for Two River Basins in Malawi","Mokkenstorm, Lone C. (Lund University; Netherlands Red Cross); van den Homberg, Marc J.C. (Netherlands Red Cross); Winsemius, H.C. (TU Delft Water Resources; Deltares; Rainbow Sensing); Persson, Andreas (Lund University)","","2021","Detecting and forecasting riverine floods is of paramount importance for adequate disaster risk management and humanitarian response. However, this is challenging in data-scarce and ungauged river basins in developing countries. Satellite remote sensing data offers a cost-effective, low-maintenance alternative to the limited in-situ data when training, parametrizing and operating flood models. Utilizing the signal difference between a measurement (M) and a dry calibration (C) location in Passive Microwave Remote Sensing (PMRS), the resulting rcm index simulates river discharge in the measurement pixel. Whilst this has been demonstrated for several river basins, it is as of yet unknown at what ratio of the spatial scales of the river width vs. the PMRS pixel resolution it remains effective in East-Africa. This study investigates whether PMRS imagery at 37 GHz can be effectively used for flood preparedness in two small-scale basins in Malawi, the Shire and North Rukuru river basins. Two indices were studied: The m index (rcm expressed as a magnitude relative to the average flow) and a new index that uses an additional wet calibration cell: rcmc. Furthermore, the results of both indices were benchmarked against discharge estimates from the Global Flood Awareness System (GloFAS). The results show that the indices have a similar seasonality as the observed discharge. For the Shire River, rcmc had a stronger correlation with discharge (ρ = 0.548) than m (ρ = 0.476), and the former predicts discharge more accurately (R2 = 0.369) than the latter (R2 = 0.245). In Karonga, the indices performed similarly. The indices do not perform well in detecting individual flood events when comparing the signal to a flood impact database. However, these results are sensitive to the threshold used and the impact database quality. The method presented simulated Shire River discharge and detected floods more accurately than GloFAS. It therefore shows potential for river monitoring in data-scarce areas, especially for rivers of a similar or larger spatial scale than the Shire River. Upstream pixels could not directly be used to forecast floods occurring downstream in these specific basins, as the time lag between discharge peaks did not provide sufficient warning time.","disaster risk; early warning; flood modeling; malawi; physical geography; remote sensing; riverine floods","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:8eccf032-4529-4e96-b762-2ab6eebf4379","http://resolver.tudelft.nl/uuid:8eccf032-4529-4e96-b762-2ab6eebf4379","Integrating inland and coastal water quality data for actionable knowledge","El Serafy, G.Y.H. (TU Delft Mathematical Physics; Deltares); Schaeffer, Blake A. (U.S. Environmental Protection Agency); Neely, Merrie-Beth (Global Science and Technology); Spinosa, A. (TU Delft Mathematical Physics; Deltares); Odermatt, Daniel (Swiss Federal Institute of Aquatic Science and Technology); Weathers, Kathleen C. (Cary Institute of Ecosystem Studies); Baracchini, Theo (Swiss Federal Institute of Aquatic Science and Technology; Swiss Federal Institute of Technology); Bouffard, Damien (Swiss Federal Institute of Aquatic Science and Technology); Carvalho, Laurence (UK Centre for Ecology & Hydrology)","","2021","Water quality measures for inland and coastal waters are available as discrete samples from professional and volunteer water quality monitoring programs and higher-frequency, near-continuous data from automated in situ sensors. Water quality parameters also are estimated from model outputs and remote sensing. The integration of these data, via data assimilation, can result in a more holistic characterization of these highly dynamic ecosystems, and consequently improve water resource management. It is becoming common to see combinations of these data applied to answer relevant scientific questions. Yet, methods for scaling water quality data across regions and beyond, to provide actionable knowledge for stakeholders, have emerged only recently, particularly with the availability of satellite data now providing global coverage at high spatial resolution. In this paper, data sources and existing data integration frameworks are reviewed to give an overview of the present status and identify the gaps in existing frameworks. We propose an integration framework to provide information to user communities through the the Group on Earth Observations (GEO) AquaWatch Initiative. This aims to develop and build the global capacity and utility of water quality data, products, and information to support equitable and inclusive access for water resource management, policy and decision making.","Coastal; Estuary; Integration; Interoperabil-ity; Lake; Management; Remote sensing; Sensors; Water quality","en","review","","","","","","","","","","","Mathematical Physics","","",""
"uuid:88ac6085-1955-4243-87fd-d8e46e82c0fc","http://resolver.tudelft.nl/uuid:88ac6085-1955-4243-87fd-d8e46e82c0fc","An overview of monitoring methods for assessing the performance of nature-based solutions against natural hazards","Kumar, Prashant (University of Surrey; Trinity College Dublin); Debele, Sisay E. (University of Surrey); Sahani, Jeetendra (University of Surrey); Rawat, Nidhi (University of Surrey); Marti-Cardona, Belen (University of Surrey); Alfieri, S.M. (TU Delft Optical and Laser Remote Sensing); Basu, Bidroha (Trinity College Dublin; University College Dublin); Basu, Arunima Sarkar (University College Dublin); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences)","","2021","To bring to fruition the capability of nature-based solutions (NBS) in mitigating hydro-meteorological risks (HMRs) and facilitate their widespread uptake require a consolidated knowledge-base related to their monitoring methods, efficiency, functioning and the ecosystem services they provide. We attempt to fill this knowledge gap by reviewing and compiling the existing scientific literature on methods, including ground-based measurements (e.g. gauging stations, wireless sensor network) and remote sensing observations (e.g. from topographic LiDAR, multispectral and radar sensors) that have been used and/or can be relevant to monitor the performance of NBS against five HMRs: floods, droughts, heatwaves, landslides, and storm surges and coastal erosion. These can allow the mapping of the risks and impacts of the specific hydro-meteorological events. We found that the selection and application of monitoring methods mostly rely on the particular NBS being monitored, resource availability (e.g. time, budget, space) and type of HMRs. No standalone method currently exists that can allow monitoring the performance of NBS in its broadest view. However, equipments, tools and technologies developed for other purposes, such as for ground-based measurements and atmospheric observations, can be applied to accurately monitor the performance of NBS to mitigate HMRs. We also focused on the capabilities of passive and active remote sensing, pointing out their associated opportunities and difficulties for NBS monitoring application. We conclude that the advancement in airborne and satellite-based remote sensing technology has signified a leap in the systematic monitoring of NBS performance, as well as provided a robust way for the spatial and temporal comparison of NBS intervention versus its absence. This improved performance measurement can support the evaluation of existing uncertainty and scepticism in selecting NBS over the artificially built concrete structures or grey approaches by addressing the questions of performance precariousness. Remote sensing technical developments, however, take time to shift toward a state of operational readiness for monitoring the progress of NBS in place (e.g. green NBS growth rate, their changes and effectiveness through time). More research is required to develop a holistic approach, which could routinely and continually monitor the performance of NBS over a large scale of intervention. This performance evaluation could increase the ecological and socio-economic benefits of NBS, and also create high levels of their acceptance and confidence by overcoming potential scepticism of NBS implementations.","In-situ measurement; Key performance indicators; NBS monitoring; Remote sensing; Synthetic aperture radar","en","review","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:f40fbf4d-540b-443c-ade6-0f9f18dc6350","http://resolver.tudelft.nl/uuid:f40fbf4d-540b-443c-ade6-0f9f18dc6350","Towards including dynamic vegetation parameters in the EUMETSAT H SAF ASCAT soil moisture products","Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning); Hahn, Sebastian (Technische Universität Wien); Wagner, Wolfgang (Technische Universität Wien); Vreugdenhil, M. (Technische Universität Wien)","","2021","The TU Wien Soil Moisture Retrieval (TUW SMR) approach is used to produce several operational soil moisture products from the Advanced Scatterometer (ASCAT) on the Metop series of satellites as part of the EUMETSAT Satellite Application Facility on Support to Operational Hydrology and Water Management (H SAF). The incidence angle dependence of backscatter is described by a second-order Taylor polynomial, the coefficients of which are used to normalize ASCAT observations to the reference incidence angle of 40° and for correcting vegetation effects. Recently, a kernel smoother was developed to estimate the coefficients dynamically, in order to account for interannual variability. In this study, we used the kernel smoother for estimating these coefficients, where we distinguished for the first time between their two uses, meaning that we used a short and fixed window width for the backscatter normalisation while we tested different window widths for optimizing the vegetation correction. In particular, we investigated the impact of using the dynamic vegetation parameters on soil moisture retrieval. We compared soil moisture retrievals based on the dynamic vegetation parameters to those estimated using the current operational approach by examining their agreement, in terms of the Pearson correlation coefficient, unbiased RMSE and bias with respect to in situ soil moisture. Data from the United States Climate Research Network were used to study the influence of climate class and land cover type on performance. The sensitivity to the kernel smoother half-width was also investigated. Results show that estimating the vegetation parameters with the kernel smoother can yield an improvement when there is interannual variability in vegetation due to a trend or a change in the amplitude or timing of the seasonal cycle. However, using the kernel smoother introduces high-frequency variability in the dynamic vegetation parameters, particularly for shorter kernel half-widths. Keywords: soil moisture; backscatter; radar remote sensing;.","ASCAT; Backscatter; Radar remote sensing; Scatterometry; Soil moisture; Vegetation","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:6ee05ef1-4459-4627-a681-564cad40b04c","http://resolver.tudelft.nl/uuid:6ee05ef1-4459-4627-a681-564cad40b04c","Spectral and growth characteristics of willows and maize in soil contaminated with a layer of crude or refined oil","Serrano Calvo, R. (TU Delft Atmospheric Remote Sensing; University of Dundee); Cutler, Mark E.J. (University of Dundee); Bengough, Anthony Glyn (University of Dundee; The James Hutton Institute)","","2021","Remote sensing holds great potential for detecting stress in vegetation caused by hydro-carbons, but we need to better understand the effects of hydrocarbons on plant growth and specific spectral expression. Willow (Salix viminalis var. Tora) cuttings and maize (Zea mays var. Lapriora) seedlings were grown in pots of loam soil containing a hydrocarbon-contaminated layer at the base of the pot (crude or refined oil) at concentrations of 0.5, 5, or 50 g·kg−1 . Chlorophyll concen-tration, biomass, and growth of plants were determined through destructive and nondestructive sampling, whilst reflectance measurements were made using portable hyperspectral spectrometers. All biophysical (chlorophyll concentration and growth) variables decreased in the presence of high concentrations of hydrocarbons, but at lower concentrations an increase in growth and chlorophyll were often observed with respect to nonpolluted plants, suggesting a biphasic response to hydrocarbon presence. Absorption features were identified that related strongly to pigment concentration and biomass. Variations in absorption feature characteristics (band depth, band area, and band width) were dependent upon the hydrocarbon concentration and type, and showed the same biphasic pattern noted in the biophysical measurements. This study demonstrates that the response of plants to hydrocarbon pollution varies according to hydrocarbon concentration and that remote sensing has the potential to both detect and monitor the variable impacts of pollution in the landscape.","Absorption features; Hydrocarbon pollution; Hyperspectral remote sensing; Plant stress; Reflectance spectra; Vegetation indices","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:e668571d-ee31-44cc-a025-f1924e66ce83","http://resolver.tudelft.nl/uuid:e668571d-ee31-44cc-a025-f1924e66ce83","Rainfall retrieval using commercial microwave links: Effect of sampling strategy on retrieval accuracy","Pudashine, Jayaram (Monash University); Guyot, Adrien (Monash University); Overeem, A. (Wageningen University & Research; Royal Netherlands Meteorological Institute (KNMI)); Pauwels, Valentijn R.N. (Monash University); Seed, Alan (Griffith University); Uijlenhoet, R. (TU Delft Water Resources); Prakash, Mahesh (Data 61-CSIRO)","","2021","This study presents the first evaluation of using commercial microwave link (CML) data for rainfall measurements in Australia, with the test site being the greater Melbourne Metropolitan area. More than 100 CMLs with microwave frequency ranging between 10 and 40 GHz have been used for the rainfall retrieval. The 15-minute received signal levels (RSLs) for each CML based on two sampling strategies (average and minimum/maximum) collected for 2 years provided a unique dataset to compare performances of rainfall retrievals. The open source algorithm RAINLINK was used for deriving rainfall from the 15-minute RSL data. From two years of data, a subset of 30 rainy days distributed across this period were used for calibrating the RAINLINK parameters, with the remaining data used for validation. For this study, only path-averaged rainfall intensities were validated based on a gauge-adjusted radar product serving as the reference. The result of the wet-dry classification showed that the minimum and maximum RSL data performed better, with lower probability of false detection and higher Matthews correlation coefficient than average RSL data. For the rainfall retrieval, both datasets showed similar correlation with the gauge adjusted radar product. However, based on other statistics (RMSE, bias and CV) minimum and maximum RSL data outperformed average for the rainfall retrieval. Overall, this study highlights the robust accuracy of commercial microwave links for rainfall retrieval while using only minimum and maximum RSL data.","Cellular communication networks; Microwave links; Opportunistic sensing; Rainfall; Remote sensing","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-03-14","","","Water Resources","","",""
"uuid:0ef2ac1a-6944-4f4b-b57b-31f639e7746a","http://resolver.tudelft.nl/uuid:0ef2ac1a-6944-4f4b-b57b-31f639e7746a","A Self-Adaptive Method for Mapping Coastal Bathymetry On-The-Fly from Wave Field Video","Gawehn, M.A. (TU Delft Coastal Engineering; Deltares); de Vries, S. (TU Delft Coastal Engineering); Aarninkhof, S.G.J. (TU Delft Hydraulic Engineering)","","2021","Mapping coastal bathymetry from remote sensing becomes increasingly more attractive for the coastal community. It is facilitated by a rising availability of drone and satellite data, advances in data science, and an open-source mindset. Coastal bathymetry, but also wave directions, celerity and near-surface currents can simultaneously be derived from aerial video of a wave field. However, the required video processing is usually extensive, requires skilled supervision, and is tailored to a fieldsite. This study proposes a video-processing algorithm that resolves these issues. It automatically adapts to the video data and continuously returns mapping updates and thereby aims to make wave-based remote sensing more inclusive to the coastal community. The code architecture for the first time includes the dynamic mode decomposition (DMD) to reduce the data complexity of wavefield video. The DMD is paired with loss-functions to handle spectral noise and a novel spectral storage system and Kalman filter to achieve fast converging measurements. The algorithm is showcased for fieldsites in the USA, the UK, the Netherlands, and Australia. The performance with respect to mapping bathymetry was validated using ground truth data. It was demonstrated that merely 32 s of video footage is needed for a first mapping update with average depth errors of 0.9–2.6 m. These further reduced to 0.5–1.4 m as the videos continued and more mapping updates were returned. Simultaneously, coherent maps for wave direction and celerity were achieved as well as maps of local near-surface currents. The algorithm is capable of mapping the coastal parameters on-the-fly and thereby offers analysis of video feeds, such as from drones or operational camera installations. Hence, the innovative application of analysis techniques like the DMD enables both accurate and unprecedentedly fast coastal reconnaissance. The source code and data of this article are openly available.","Bathymetry; Coastal zone; Depth inversion; Dynamic mode decomposition; On-the-fly; Remote sensing; Waves","en","journal article","","","","","","","","","","Hydraulic Engineering","Coastal Engineering","","",""
"uuid:a2f9a46b-b42f-4f69-977b-3fdc2afc13a2","http://resolver.tudelft.nl/uuid:a2f9a46b-b42f-4f69-977b-3fdc2afc13a2","Assessing sponge cities performance at city scale using remotely sensed LULC changes: Case study Nanjing","Liu, X. (TU Delft Hydraulic Structures and Flood Risk; Southeast University; IHE Delft Institute for Water Education); Fu, Dafang (Southeast University); Zevenbergen, C. (TU Delft Hydraulic Structures and Flood Risk; TU Delft Urban Design; IHE Delft Institute for Water Education); Busker, Tim (Vrije Universiteit Amsterdam); Yu, Meixiu (Hohai University)","","2021","As a result of high-density urbanization and climate change, both the frequency and intensity of extreme urban rainfall are increasing. Drainage systems are not designed to cope with this increase, and as a result, floods are becoming more common in cities, particularly in the rapidly growing cities of China. To better cope with more frequent and severe urban flooding and to improve the water quality of stormwater runoff, the Chinese government launched the national Sponge City Construction (SCC) program in 2014. The current SCC design standards and guidelines are based on static values (e.g., return periods, rainfall intensities, and volume capture ratio (VCR)). They do not fully acknowledge the large differences in climate conditions across the country and assume that the hydraulic conditions will not change over time. This stationary approach stems from the traditional engineering approach designed for grey infrastructure (following a “one size fits all” approach). The purpose of this study was to develop a methodology to assess the VCR baseline (before construction in the pre-development stage) and changes in VCR (difference between the VCR of the pre-and post-development stage). The VCR of the post-development stage is one of the required indicators of the Assessment Standard for Sponge Cities Effects to evaluate SCC projects. In this study, the VCR was derived from remote-sensing-based land use land cover (LULC) change analysis, applying an unsupervised classification algorithm on different Landsat images from 1985 to 2015. A visualization method (based upon Sankey chart, which depicts the flows and their proportions of components) and a novel and practical partitioning method for built-up regions were developed to visualize and quantify the states and change flows of LULC. On the basis of these findings, we proposed a new indicator, referred to as VCRa − L, in order to assess the changes in urban hydrology after SCC construction. This study employed the city of Nanjing as a case study and analyzed detailed information on how LULC changes over time of built-up areas. The surface area of the urban and built-up areas of Nanjing quadrupled from 11% in 1985 to 44% in 2015. In the same period, neither the entire city nor its subregions reached the VCR target of 80%. The proposed new methodology aims to support national, regional, and city governments to identify and prioritize where to invest and implement SCC measures more effectively in cities across China.","Built-up area partitioning method; Google earth engine; Land use change; Modified Sankey chart; Remote sensing; Sponge city construction; Volume capture ratio","en","journal article","","","","","","","","","","","Hydraulic Structures and Flood Risk","","",""
"uuid:c098bf6f-b04d-4dea-a6c9-7b6bcc6447fb","http://resolver.tudelft.nl/uuid:c098bf6f-b04d-4dea-a6c9-7b6bcc6447fb","Eleven years of mangrove–mudflat dynamics on the mud volcano-induced prograding delta in east java, indonesia: Integrating uav and satellite imagery","Beselly, S.M. (TU Delft Coastal Engineering; IHE Delft Institute for Water Education; Brawijaya University); van der Wegen, Mick (IHE Delft Institute for Water Education; Deltares); Grueters, Uwe (Justus Liebig University Giessen); Reyns, J.A.H. (IHE Delft Institute for Water Education; Deltares); Dijkstra, Jasper (Deltares); Roelvink, D. (TU Delft Coastal Engineering; IHE Delft Institute for Water Education; Deltares)","","2021","This article presents a novel approach to explore mangrove dynamics on a prograding delta by integrating unmanned aerial vehicle (UAV) and satellite imagery. The Porong Delta in Indonesia has a unique geographical setting with rapid delta development and expansion of the mangrove belt. This is due to an unprecedented mud load from the LUSI mud volcanic eruption. The mangrove dynamics analysis combines UAV-based Structure from Motion (SfM) photogrammetry and 11 years (2009–2019) satellite imagery cloud computing analysis by Google Earth Engine (GEE). Our analysis shows unique, high-spatiotemporal-resolution mangrove extent maps. The SfM pho-togrammetry analysis leads to a 3D representation of the mangrove canopy and an estimate of mangrove biophysical properties with accurate height and individual position of the mangroves stand. GEE derived vegetation indices resulted in high (three-monthly) resolution mangrove coverage dynamics over 11 years (2009–2019), yielding a value of more than 98% for the overall, producer and consumer accuracy. Combining the satellite-derived age maps and the UAV-derived spatial tree structure allowed us to monitor the mangrove dynamics on a rapidly prograding delta along with its structural attributes. This analysis is of essential value to ecologists, coastal managers, and poli-cymakers.","Google Earth Engine; Mangroves; Remote sensing; SfM Photogrammetry; UAV","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:888982c7-9758-4c6a-9e1f-c5b16374bad1","http://resolver.tudelft.nl/uuid:888982c7-9758-4c6a-9e1f-c5b16374bad1","Anisotropy parameterization development and evaluation for glacier surface albedo retrieval from satellite observations","Ren, Shaoting (Chinese Academy of Sciences; University of Chinese Academy of Sciences; Swiss Federal Institute for Forest, Snow and Landscape Research); Miles, Evan S. (Swiss Federal Institute for Forest, Snow and Landscape Research); Jia, Li (Chinese Academy of Sciences); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Kneib, Marin (Swiss Federal Institute for Forest, Snow and Landscape Research; ETH Zürich); Buri, Pascal (Swiss Federal Institute for Forest, Snow and Landscape Research); McCarthy, Michael J. (Swiss Federal Institute for Forest, Snow and Landscape Research; British Antarctic Survey); Shaw, Thomas E. (Swiss Federal Institute for Forest, Snow and Landscape Research); Yang, Wei (Chinese Academy of Sciences); Pellicciotti, Francesca (Swiss Federal Institute for Forest, Snow and Landscape Research; University of Northumbria)","","2021","Glacier albedo determines the net shortwave radiation absorbed at the glacier surface and plays a crucial role in glacier energy and mass balance. Remote sensing techniques are efficient means to retrieve glacier surface albedo over large and inaccessible areas and to study its variability. However, corrections of anisotropic reflectance of glacier surface have been established for specific shortwave bands only, such as Landsat 5 Thematic Mapper (L5/TM) band 2 and band 4, which is a major limitation of current retrievals of glacier broadband albedo. In this study, we calibrated and evaluated four anisotropy correction models for glacier snow and ice, applicable to visible, near-infrared and shortwave-infrared wavelengths using airborne datasets of Bidirectional Reflectance Distribution Function (BRDF). We then tested the ability of the best-performing anisotropy correction model, referred to from here on as the ‘updated model’, to retrieve albedo from L5/TM, Landsat 8 Operational Land Imager (L8/OLI) and Moderate Resolution Imaging Spectroradiometer (MODIS) imagery, and evaluated these results with field measurements collected on eight glaciers around the world. Our results show that the updated model: (1) can accurately estimate anisotropic factors of reflectance for snow and ice surfaces; (2) generally performs better than prior approaches for L8/OLI albedo retrieval but is not appropriate for L5/TM; (3) generally retrieves MODIS albedo better than the MODIS standard albedo product (MCD43A3) in both absolute values and glacier albedo temporal evolution, i.e., exhibiting both fewer gaps and better agreement with field obser-vations. As the updated model enables anisotropy correction of a maximum of 10 multispectral bands and is implemented in Google Earth Engine (GEE), it is promising for observing and analyz-ing glacier albedo at large spatial scales.","Albedo retrieval; Anisotropy correction; Glacier surface albedo; Remote sensing","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:1cdf2397-6c30-41d0-a5fd-3511994030eb","http://resolver.tudelft.nl/uuid:1cdf2397-6c30-41d0-a5fd-3511994030eb","SHM of Vibrating Stay-Cables by Microwave Remote Sensing","Cabboi, A. (TU Delft Mechanics and Physics of Structures); Gentile, Carmelo (Politecnico di Milano); Zonno, Giacomo (Politecnico di Milano)","Rizzo, Piervincenzo (editor); Milazzo, Alberto (editor)","2021","A radar equipment was used to measure the deflection response of bridge stay-cables induced by ambient and traffic excitation. After a concise description of the radar equipment and a summary of advantages and potential issues of the microwave technology, the paper focuses on the experimental tests performed on all stay-cables of the curved cable-stayed bridge erected in the commercial harbor of Porto Marghera, Venice, Italy. The bridge consists of an inclined concrete tower, single-plane cables and a composite deck; the curved deck has a centerline length of 231 m, with two different side spans and 9 cables supporting each side span. Three series of ambient vibration tests were performed (on July 2010, April 2011 and October 2019) on the two arrays of cables of the bridge by using conventional accelerometers and microwave interferometer. The availability of simultaneously collected radar and accelerometer data (which are usually regarded as reference data in dynamic tests) allowed to investigate the accuracy of the radar technique (in terms of natural frequencies and tensile force estimated from natural frequencies) and the errors/uncertainties in radar results. Furthermore, the tests allowed to verify the repeatability of radar survey, with SHM purposes.","Dynamic testing; Microwave remote sensing; Radar; Stay-cable; Structural Health Monitoring","en","conference paper","Springer","","","","","Accepted author manuscript","","2022-01-09","","","Mechanics and Physics of Structures","","",""
"uuid:d8fa4d5f-eb9a-47f5-a77d-355458683ea9","http://resolver.tudelft.nl/uuid:d8fa4d5f-eb9a-47f5-a77d-355458683ea9","Space-based SAR and optical remote sensing for productivity monitoring and mapping of sugarcane","Molijn, R.A.","Hanssen, R.F. (promotor); Vieira Rocha, Jansle (promotor); Delft University of Technology (degree granting institution); University of Campinas (degree granting institution)","2020","In this study, research on productivity and land cover monitoring is presented, with a focus on sugarcane, based on space-based remote sensing observations that were collected by Synthetic Aperture Radar (SAR) and optical sensors. The study aims to provide new insights into techniques and methodologies that allow for cost-efficient monitoring of sugarcane productivity and the wide-scale expansion of sugarcane over long time series. It is part of a wider framework of research projects, sharing the overarching goal to contribute to a biobased society, where the resources for the production of chemicals, materials and energy are based on biomass, produced in a competitive and sustainable manner. São Paulo state, Brazil, was selected as study area, primarily because it is one of the most prominent regions worldwide that hosts sugarcane, which is one of the most prominent crops for bio-energy production.
The study includes the following research.
First of all, results are presented that are based on a wide range of biophysical measurements that were collected during a year-long ground measurement campaign in several sugarcane fields. These results are accompanied by detailed quality assessments, illustrating their reliability when collecting such measurements through such campaigns. In addition, the methodology for setting up and carrying out the ground campaign is explained, which was designed to minimize biomass alterations in the field in light of the use of the measurements for validation of space-based SAR and optical remote sensing signals.
Secondly, remote sensing signals from various satellites are compared to the ground reference measurements in order to develop space-based sugarcane productivity monitoring techniques. It includes an analysis on the sensitivity of C-band and L-band SAR and optical observations to sugarcane biomass growth, to precipitation events and to SAR sensor configurations. In addition, the spatial features in satellite imagery from the various sensors are analyzed for their temporal consistencies in order to deduce time windows during which the satellite observations are most effective for productivity monitoring. It was found that especially saturation, precipitation and sensor configurations dictate the effectiveness, particularly for SAR. Furthermore, the highest spatial resolution optical imagery proved to perform best for mapping intra-field productivity differences that were measured in the field. In addition to this study, two related but smaller studies are presented. The first focuses on a specific remote sensing technique to identify patterns in a sugarcane field that occur persistently in time. The second demonstrates how plant gaps in a densely ground-measured sugarcane field affect signals from various SAR and how this effect is influenced by spatial averaging windows, precipitation events, sugarcane height and SAR sensor type.
Thirdly, the performance of a specific Bayesian land cover monitoring model that combines SAR and optical observations is demonstrated. The model is an adaptation of the Hidden Markov Model, which allows for the temporally-consistent tracking of vegetation states regardless of gaps in satellite observations. Attention is paid to the effect of precipitation during SAR observations on the model's performance and to certain vegetation conditions that cause classification confusion between land cover types. The research finally provides detailed insights into when SAR-only observations outperform optical-only observations and vice versa, in addition to the advantages when combining them.
Finally, a technique is introduced that exploits SAR signal fluctuations caused by varying (ground and plant) surface wetness conditions in order to improve the characterization of vegetation. Three scenarios that define the selection of SAR observations were investigated for their effect on the classification performance: (i) no distinction between wetness conditions, (ii) distinction between wetness conditions at the time of the SAR acquisitions and (iii) distinction between wetness conditions between consecutive SAR acquisitions. Particularly when the wetness conditions differ under the last scenario, it was found that performances improve. When combining this information with a-priori knowledge on soil types, the accuracy of the classification further increases. For this, maps are used that are a result from applying the previously introduced Hidden Markov Model over the entire state of São Paulo.
The datasets that are used in these studies were mainly acquired by the SAR satellites Sentinel-1, Radarsat-2 and ALOS-2, and by the optical satellites Landsat-8 and Worldview-2. For the studies that are related to land cover monitoring and vegetation characterization, high performance computing was required due to the vast amount of observation data and the complexity of the applied techniques. These facilities were mainly provided by the Dutch national supercomputer of SURF and by Google Earth Engine.","SAR and optical remote sensing; Sugarcane; Growth monitoring; Land cover mapping; Ground reference measurements; Data Assimiliation; Saturation effects","en","doctoral thesis","Delft University Publishers","978-94-6366-252-9","","","","","","","","Geoscience and Remote Sensing","","","",""
"uuid:da8e1ff5-2a76-47b1-9ba8-503a3d64ae26","http://resolver.tudelft.nl/uuid:da8e1ff5-2a76-47b1-9ba8-503a3d64ae26","A novel method to quantify consumed fractions and non-consumptive use of irrigation water: Application to the indus Basin irrigation system of Pakistan","Simons, G.W.H. (TU Delft Water Resources; FutureWater -Wageningen); Bastiaanssen, W.G.M. (TU Delft Water Resources); Cheema, M.J.M. (PMAS Arid Agriculture University); Ahmad, B. (Pakistan Agricultural Research Council (PARC)); Immerzeel, W.W. (Universiteit Utrecht)","","2020","Increasing irrigation efficiencies remains the focus of numerous efforts to mitigate water scarcity. In reality, higher local efficiencies do often not reduce water scarcity, but instead cause a redistribution of water flows when the entire irrigation scheme or river basin is considered. Insufficient understanding of consumed fractions and non-consumptive use (i.e. return flows) have led to ineffective, or even harmful, water conservation measures. In this paper, we demonstrate a novel method for spatial quantification of the Consumed Fraction (CF) of withdrawn irrigation water based on satellite remote sensing and the Budyko Hypothesis. This method was applied to evaluate consumption of irrigation water (ETblue), total water supply, and non-consumptive use across the Indus Basin Irrigation System (IBIS) of Pakistan. An average ETblue of 707 mm/yr from irrigated cropland was found for 2004–2012, with values per Canal Command Area (CCA) varying from 421 mm/yr to 1011 mm/yr. Although canal supply (662 mm/yr on average) in most CCAs was largely sufficient to sustain ETblue, a similar volume of additional pumping (690 mm/yr) was required to comply with hydro-climatological principles prescribed by Budyko theory. CF values between 0.38 and 0.66 were computed at CCA level, with an average value of 0.52. Co-occurrence of relatively low CF values, high additional water supply, and long-term canal diversions similar to ETblue, implies that the IBIS is characterized by extensive reuse of non-consumed flows within CCAs. In addition, the notably higher CF of 0.71−0.93 of the full IBIS indicates that return flow reuse between CCAs cannot be neglected. These conclusions imply that the IBIS network of irrigators is adapted to extensively recover and reuse drainage flows on different spatial scales. Water saving and efficiency enhancement measures should therefore be implemented with great caution. By relying on globally available satellite products and limited additional data, this novel method to determine Consumed Fractions and non-consumed flows can support policy makers worldwide to make irrigation systems more efficient without detriment to downstream users.","Budyko; Consumed fraction; Non-Consumptive use; Remote sensing; Water reuse","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:b405a7c3-481f-4f64-87fb-75c90754f1b3","http://resolver.tudelft.nl/uuid:b405a7c3-481f-4f64-87fb-75c90754f1b3","Seasonal and Spatial Variability in Patchiness of Microphytobenthos on Intertidal Flats From Sentinel-2 Satellite Imagery","Daggers, Tisja D. (Universiteit Utrecht); Herman, P.M.J. (TU Delft Environmental Fluid Mechanics; Deltares); van der Wal, Daphne (Universiteit Utrecht; University of Twente)","","2020","Understanding the spatial structure of microphytobenthos (MPB) on intertidal flats is necessary to gain insight in the benthic community structure and ecosystem processes. The increasing availability of high resolution satellite sensors provides the opportunity to better understand spatial patterns of MPB on various (meter to km) scales. We tested how MPB patch size (indicated by the range derived from a semi-variogram) and degree of patchiness (indicated by the sill) vary as function of seasons, salinity, tidal flat type (muddy fringing versus sandy mid-channel tidal flats) or ecotopes (defined by hydrodynamics, silt content and elevation), in the Westerschelde estuary, the Netherlands. We used Sentinel-2 imagery (2016–2019) with 10 m spatial resolution to derive (omnidirectional) semi-variogram parameters from the NDVI (used as indicator for MPB biomass) and evaluated (seasonality in) patchiness of MPB in the different categories. We demonstrated that MPB patch size (the range) remains constant from winter to summer, while the sill increased from winter to summer. The location of patches on tidal flats was variable throughout the year and shows a remarkable similarity with seasonality in the spatial heterogeneity of the silt content on tidal flats. The patch size and degree of patchiness is higher on relatively sandy mid-channel tidal flats than on relatively silt rich fringing tidal flats. This implies that spatial patterning of MPB biomass on the meso-scale is likely closely linked to abiotic conditions and that spreading processes or grazing activity play a minor role. We observed visually that some areas with a relatively high MPB biomass (‘patches’) remain visible throughout the year, while other patches were only present during a particular season.","intertidal flats; microphytobenthos; patchiness; remote sensing; silt","en","journal article","","","","","","","","","","","Environmental Fluid Mechanics","","",""
"uuid:b4d9e6a5-4366-4350-a157-2024caceb015","http://resolver.tudelft.nl/uuid:b4d9e6a5-4366-4350-a157-2024caceb015","Improving ASCAT Soil Moisture Retrievals With an Enhanced Spatially Variable Vegetation Parameterization","Hahn, Sebastian (Technische Universität Wien); Wagner, Wolfgang (Technische Universität Wien); Steele-Dunne, S.C. (TU Delft Mathematical Geodesy and Positioning); Vreugdenhil, M. (Technische Universität Wien); Melzer, Thomas (Technische Universität Wien)","","2020","This study investigates the performance of the TU Wien soil moisture retrieval (TUW-SMR) algorithm by adapting the strength of the vegetation correction. The semiempirical change detection method TUW-SMR exploits the multiangle backscatter observations from spaceborne fan-beam scatterometer systems in order to derive surface soil moisture information expressed in the degree of saturation. The vegetation parameterization of TUW-SMR is controlled by the dry and wet crossover angles that are used to determine the dry and wet backscatter reference. Backscatter observations from the Advanced Scatterometer (ASCAT) are used to produce four soil moisture data sets based on different dry and wet crossover angles describing: 1) a static, respectively, no vegetation correction; 2) the currently used seasonal vegetation correction; 3) a stronger seasonal vegetation correction; and 4) a spatially variable seasonal vegetation correction with the stronger vegetation correction over vegetated areas and no vegetation correction over bare land. All four ASCAT soil moisture data sets are evaluated against soil moisture estimates from GLDAS-2.1 Noah land surface model and the European Space Agency (ESA) climate change initiative (CCI) Passive v04.5 soil moisture product using the triple collocation method and traditional correlation analysis. The results show that the spatially variable vegetation correction overall improves soil moisture estimates in both more densely vegetated areas, e.g., in large parts of North America and Europe, and more sparsely vegetated, e.g., Western Africa. Nonetheless, the experiment also provides insight into challenging retrieval conditions where the TUW-SMR fails to take all relevant backscatter processes into account, e.g., wetlands and bare soils with subsurface scattering.","Performance evaluation; radar cross sections; radar remote sensing; soil moisture","en","journal article","","","","","","Accepted Author Manuscript","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:b41149d8-4aff-4024-89eb-0969999a4e94","http://resolver.tudelft.nl/uuid:b41149d8-4aff-4024-89eb-0969999a4e94","Inconsistencies between chemistry–climate models and observed lower stratospheric ozone trends since 1998","Ball, W.T. (TU Delft Atmospheric Remote Sensing; ETH Zürich; PMOD WRC); Chiodo, Gabriel (ETH Zürich; Columbia University); Abalos, Marta (Universidad Complutense de Madrid); Alsing, Justin (Stockholm University; Imperial College London); Stenke, Andrea (ETH Zürich)","","2020","The stratospheric ozone layer shields surface life from harmful ultraviolet radiation. Following the Montreal Protocol ban on long-lived ozone-depleting substances (ODSs), rapid depletion of total column ozone (TCO) ceased in the late 1990s, and ozone above 32 km is now clearly recovering. However, there is still no confirmation of TCO recovery, and evidence has emerged that ongoing quasi-global (60∘ S–60∘ N) lower stratospheric ozone decreases may be responsible, dominated by low latitudes (30∘ S–30∘ N). Chemistry–climate models (CCMs) used to project future changes predict that lower stratospheric ozone will decrease in the tropics by 2100 but not at mid-latitudes (30–60∘). Here, we show that CCMs display an ozone decline similar to that observed in the tropics over 1998–2016, likely driven by an increase in tropical upwelling. On the other hand, mid-latitude lower stratospheric ozone is observed to decrease, while CCMs that specify real-world historical meteorological fields instead show an increase up to present day. However, these cannot be used to simulate future changes; we demonstrate here that free-running CCMs used for projections also show increases. Despite opposing lower stratospheric ozone changes, which should induce opposite temperature trends, CCMs and observed temperature trends agree; we demonstrate that opposing model–observation stratospheric water vapour (SWV) trends, and their associated radiative effects, explain why temperature changes agree in spite of opposing ozone trends. We provide new evidence that the observed mid-latitude trends can be explained by enhanced mixing between the tropics and extratropics. We further show that the temperature trends are consistent with the observed mid-latitude ozone decrease. Together, our results suggest that large-scale circulation changes expected in the future from increased greenhouse gases (GHGs) may now already be underway but that most CCMs do not simulate mid-latitude ozone layer changes well. However, it is important to emphasise that the periods considered here are short, and internal variability that is both intrinsic to each CCM and different to observed historical variability is not well-characterised and can influence trend estimates. Nevertheless, the reason CCMs do not exhibit the observed changes needs to be identified to allow models to be improved in order to build confidence in future projections of the ozone layer.","Ozone; Stratosphere; water vapor; Remote sensing; Climate modeling","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:13bb3665-f4b3-4608-8663-671aa764d629","http://resolver.tudelft.nl/uuid:13bb3665-f4b3-4608-8663-671aa764d629","Damage accelerates ice shelf instability and mass loss in Amundsen Sea Embayment","Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning); Sun, Sainan (Vrije Universiteit Brussel); Shuman, Christopher (NASA Goddard Space Flight Center); Wouters, B. (TU Delft Physical and Space Geodesy; Universiteit Utrecht); Pattyn, Frank (Vrije Universiteit Brussel); Wuite, Jan (ENVEO IT GmbH); Berthier, Etienne (CNES Centre National d'Etudes Spatiales; Université Paul Sabatier; IRD Institut de Recherche pour le Developpement; CNRS); Nagler, Thomas (ENVEO IT GmbH)","","2020","Pine Island Glacier and Thwaites Glacier in the Amundsen Sea Embayment are among the fastest changing outlet glaciers in West Antarctica with large consequences for global sea level. Yet, assessing how much and how fast both glaciers will weaken if these changes continue remains a major uncertainty as many of the processes that control their ice shelf weakening and grounding line retreat are not well understood. Here, we combine multisource satellite imagery with modeling to uncover the rapid development of damage areas in the shear zones of Pine Island and Thwaites ice shelves. These damage areas consist of highly crevassed areas and open fractures and are first signs that the shear zones of both ice shelves have structurally weakened over the past decade. Idealized model results reveal moreover that the damage initiates a feedback process where initial ice shelf weakening triggers the development of damage in their shear zones, which results in further speedup, shearing, and weakening, hence promoting additional damage development. This damage feedback potentially preconditions these ice shelves for disintegration and enhances grounding line retreat. The results of this study suggest that damage feedback processes are key to future ice shelf stability, grounding line retreat, and sea level contributions from Antarctica. Moreover, they underline the need for incorporating these feedback processes, which are currently not accounted for in most ice sheet models, to improve sea level rise projections.","Antarctica; glaciology; ice sheet modeling; remote sensing; sea level rise","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:c6b28112-9023-49ce-b9fa-e21b3ef289a4","http://resolver.tudelft.nl/uuid:c6b28112-9023-49ce-b9fa-e21b3ef289a4","The application of a radar-based depth inversion method to monitor near-shore nourishments on an open sandy coast and an ebb-tidal delta","Gawehn, M.A. (TU Delft Coastal Engineering; Deltares); van Dongeren, Ap (Deltares); de Vries, S. (TU Delft Coastal Engineering); Swinkels, Cilia (Deltares); Hoekstra, Roderik (Deltares); Aarninkhof, S.G.J. (TU Delft Hydraulic Engineering); Friedman, Joshua (Deltares)","","2020","Coastal management in the Netherlands has the aim to defend coastal zones by preventing flooding and mitigating erosion. To that end, large-scale nourishments are placed in the nearshore, which are supposed to dynamically preserve the coastal zone over a timescale of years. To assess their effectiveness, these nourishments are monitored over large areas and long durations. As repetitive, in-situ measurements become too expensive, remote sensing offers an attractive alternative, mapping depth and near-surface current fields via depth inversion algorithms (DIA). However, the information that can be derived from remotely-sensed data is subject to improvement. In this study a 3D-FFT based DIA named XMFit (X-Band Matlab Fitting) is introduced, which is robust, accurate and fast enough for operational use. Focusing on depth estimates, the algorithm was validated for two case studies in the Netherlands: (1) the “Sand Engine”, a beach mega nourishment at a uniform open coast, and (2) the tidal inlet of the Dutch Wadden Sea island Ameland, characterizing a more complex coast. Considering both sites, the algorithm performance was characterized by a spatially averaged depth bias of −0.9 m at the Sand Engine and a time-varying bias of approximately -2 – 0 m at the Ameland Inlet. When compared to in-situ depth surveys the accuracy was lower, but the time resolution higher. Depth estimates from the Ameland tidal inlet were produced every 50 min by an operational system using a navigational X-Band radar to monitor the placement of a 5 million m3 ebb-tidal delta nourishment – a pilot measure for coastal management. Volumetric changes in the nourishment area over the year 2018, occurring at 7 km distance from the radar, were estimated with an error of 7%. Depth errors statistically correlated with the direction and magnitude of simultaneous near-surface current estimates. Additional experiments on Sand Engine data demonstrated that depth errors may be significantly reduced using an alternative spectral approach and/or by using a Kalman filter.","Coastal zone; Depth inversion; Nourishment; Remote sensing; Tidal inlet; X-band radar","en","journal article","","","","","","Accepted Author Manuscript","","2022-05-11","","Hydraulic Engineering","Coastal Engineering","","",""
"uuid:acba88f3-0672-480d-9c29-7dcd159c287f","http://resolver.tudelft.nl/uuid:acba88f3-0672-480d-9c29-7dcd159c287f","Improved Understanding of the Link Between Catchment-Scale Vegetation Accessible Storage and Satellite-Derived Soil Water Index","Bouaziz, L.J.E. (TU Delft Water Resources; Deltares); Steele-Dunne, S.C. (TU Delft Water Resources); Schellekens, Jaap (VanderSat B.V.); Weerts, Albrecht H. (Deltares; Wageningen University & Research); Stam, Jasper (Rijkswaterstaat); Sprokkereef, Eric (Rijkswaterstaat); Winsemius, H.C. (TU Delft Water Resources; Deltares); Savenije, Hubert (TU Delft Water Resources); Hrachowitz, M. (TU Delft Water Resources)","","2020","The spatiotemporal dynamics of water volumes stored in the unsaturated root zone are a key control on the response of terrestrial hydrological systems. Robust, catchment-scale root-zone soil moisture estimates are thus critical for reliable predictions of river flow, groundwater recharge, or evaporation. Satellites provide estimates of near-surface soil moisture that can be used to approximate the moisture content in the entire unsaturated root zone through the Soil Water Index (SWI). The characteristic time length (T, in days), as only parameter in the SWI approach, characterizes the temporal variability of soil moisture. The factors controlling T are typically assumed to be related to soil properties and climate; however, no clear link has so far been established. In this study, we hypothesize that optimal T values (Topt) are linked to the interplay of precipitation and evaporation during dry periods, thus to catchment-scale vegetation accessible water storage capacities in the unsaturated root zone. We identify Topt by matching modeled time series of root-zone soil moisture from a calibrated process-based hydrological model to SWI from several satellite-based near-surface soil moisture products in 16 contrasting catchments in the Meuse river basin. Topt values are strongly and positively correlated with vegetation accessible water volumes that can be stored in the root zone, here estimated for each study catchment both as model calibration parameter and from a water-balance approach. Differences in Topt across catchments are also explained by land cover (% agriculture), soil texture (% silt), and runoff signatures (flashiness index).","catchment hydrology; remotely sensed near-surface soil moisture; Soil Water Index; vegetation accessible water storage","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:b9065219-7841-442d-8ea0-0d3473607254","http://resolver.tudelft.nl/uuid:b9065219-7841-442d-8ea0-0d3473607254","Development of spectral-phenological features for deep learning to understand Spartina alterniflora invasion","Tian, Jinyan (Capital Normal University); Wang, Le (University at Buffalo, State University of New York); Yin, Dameng (University at Buffalo, State University of New York); Li, Xiaojuan (Capital Normal University); Diao, Chunyuan (University of Illinois at Urbana-Champaign); Gong, Huili (Capital Normal University); Shi, Chen (Capital Normal University); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Ge, Yong (Chinese Academy of Sciences)","","2020","Invasive Spartina alterniflora (S. alterniflora), a native riparian species in the U.S. Gulf of Mexico, has led to serious degradation to the ecosystem and biodiversity as well as economic losses since it was introduced to China in 1979. Although multi-temporal remote sensing offers unique capability to monitor S. alterniflora over large areas and long time periods, three major hurdle exist: (1) in the coastal zone where S. alterniflora occupies, frequent cloud coverage reduces the number of available images that can be used; (2) prominent spectral variations exist within the S. alterniflora due to phonological variations; (3) poor spectral separability between S. alterniflora and its co-dominant native species is often presented in the territories where S. alterniflora intruded in. To articulate these questions, we proposed a new pixel-based phenological feature composite method (Ppf-CM) based on Google Earth Engine. The Ppf-CM method was brainstormed to battle the aforementioned three hurdles as the basic unit for extracting phonological feature is individual pixel in lieu of an entire image scene. With the Ppf-CM-derived phenological feature as inputs, we took a step further to investigate the performance of the latest deep learning method as opposed to that of the conventional support vector machine (SVM); Lastly, we strive to understand how S. alterniflora has changed its spatial distribution in the Beibu Gulf of China from 1995 to 2017. As a result, we found (1) the developed Ppf-CM method can mitigate the phonological variation and augment the spectral separability between S. alterniflora and the background species regardless of the significant cloud coverage in the study area; (2) deep learning, compared to SVM, presented better potentials for incorporating the new phenological features generated from the Ppf-CM method; and (3) for the first time, we discovered a S. alterniflora invasion outbreak occurred during 1996–2001.","Cloudy coastal zone; Deep learning; Google earth engine; Invasive species; Phenology; Remote sensing big data","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:0387891a-41f0-4e2f-933a-e501002ac6c9","http://resolver.tudelft.nl/uuid:0387891a-41f0-4e2f-933a-e501002ac6c9","A semi-empirical method for estimating complete surface temperature from radiometric surface temperature, a study in Hong Kong city","Yang, Jinxin (Guangzhou University); Wong, Man Sing (The Hong Kong Polytechnic University); Ho, Hung Chak (The Hong Kong Polytechnic University; The University of Hong Kong); Krayenhoff, E. Scott (University of Guelph); Chan, P. W. (Hong Kong Observatory); Abbas, Sawaid (The Hong Kong Polytechnic University); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences)","","2020","The complete surface temperature (Tc) in urban areas, defined as the mean temperature of the total active surface area, is an important variable in urban micro-climate research, specifically for assessment of the urban surface energy balance. Since most vertically-oriented building facets are not observed by a nadir-viewing remote imaging radiometer, the radiometric surface temperature (Tr) measured at a specific view angle cannot be used with existing heat transfer equations to estimate radiative and convective fluxes in the urban environment. Thus, it is necessary to derive Tc for city neighborhoods. This study develops a simple method to estimate Tc from Tr with the aid of the Temperatures of Urban Facets in 3D (TUF-3D) numerical model, which calculates 3-D sub-facet scale urban surface temperatures for a variety of surface geometries and properties, weather conditions and solar angles. The effects of geometric and meteorological characteristics – e.g., building planar area index (λp), wall facet area index (F), solar irradiance – on the difference between Tc and Tr were evaluated using the TUF-3D model. Results showed the effects of geometric and meteorological characteristics on the difference between Tc and Tr differ between daytime and nighttime. The study then sought to predict the relationship between Tr and Tc, using λp, F, and solar irradiance for daytime and only using λp and F for nighttime. Based on the simulated data from TUF-3D, the resulting relationships achieve a coefficient of determination (r2) of 0.97 and a RMSE of 1.5 K during daytime, with corresponding nighttime values of r2 = 0.98 and RMSE = 0.69 K. The relationships between Tr and Tc are evaluated using high resolution airborne thermal images of daytime urban scenes: r2 = 0.75 and RMSE = 1.09 K on August 6, 2013 at 12:40 pm; and r2 = 0.86 and RMSE = 1.86K on October 24, 2017 at 11:30 am. The new relationships were also applied to estimate Tc from Tr in Hong Kong retrieved from Landsat 5 Thematic Mapper (TM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). In the present climatic context, the difference between Tc and Tr can reach 10 K during daytime in summer, and 6 K during daytime in winter, with seasonal variation attributable to the variations in shortwave irradiance. The nighttime difference between Tc and Tr can also reach 2 K in both summer and spring seasons.","Remote sensing; Surface temperature; Thermal heterogeneity; Urban geometry","en","journal article","","","","","","Accepted Author Manuscript","","2021-11-26","","","Optical and Laser Remote Sensing","","",""
"uuid:eb1b5110-1f63-4956-be6e-7485e0959541","http://resolver.tudelft.nl/uuid:eb1b5110-1f63-4956-be6e-7485e0959541","Land surface temperature and households’ energy consumption: Who is affected and where?","Mashhoodi, B. (TU Delft Environmental Technology and Design); Stead, D. (TU Delft Spatial Planning and Strategy); van Timmeren, A. (TU Delft Environmental Technology and Design; TU Delft Amsterdam Institute for Advanced Metropolitan Solutions)","","2020","It is widely accepted that land surface temperature (LST) affects household energy consumption (HEC). There is, however, no previous study available that clarifies whether LST's impact is similar in each and every area, or if it varies from one location to another. Analysing the impact of LST on HEC of 2612 residential zones of the Netherlands in 2014, this study concludes that HEC of 50% of the zones is affected by LST, accounting for 0.8% of overall consumption on average. It is obtained that energy-intensive, high-income and large-size households are more likely to be affected by LST. The results show that the effect is likely to be significant in the zones with relatively milder air temperature, and higher levels of humidity and wind. It is obtained that the effect intensifies when the buildings are less compact and the zones are less urbanised. Ultimately, this study urges for a shift in the approach of the existing studies on the impact of LST by putting forward a proposition: the impact of LST on HEC could not be spatially generalised, and one cannot enhance the associations unless location-specific circumstances of the areas in question are taken into consideration.","Geographically weighted regression; Household energy consumption; Land surface temperature; Netherlands; Remote sensing; Urban heat island","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2020-05-29","","Amsterdam Institute for Advanced Metropolitan Solutions","Environmental Technology and Design","","",""
"uuid:6e70a980-40f6-461c-b74a-408bea1b13b8","http://resolver.tudelft.nl/uuid:6e70a980-40f6-461c-b74a-408bea1b13b8","Machine learning: New potential for local and regional deep-seated landslide nowcasting","van Natijne, A.L. (TU Delft Optical and Laser Remote Sensing); Lindenbergh, R.C. (TU Delft Optical and Laser Remote Sensing); Bogaard, T.A. (TU Delft Water Resources)","","2020","Nowcasting and early warning systems for landslide hazards have been implemented mostly at the slope or catchment scale. These systems are often difficult to implement at regional scale or in remote areas. Machine Learning and satellite remote sensing products offer new opportunities for both local and regional monitoring of deep-seated landslide deformation and associated processes. Here, we list the key variables of the landslide process and the associated satellite remote sensing products, as well as the available machine learning algorithms and their current use in the field. Furthermore, we discuss both the challenges for the integration in an early warning system, and the risks and opportunities arising from the limited physical constraints in machine learning. This review shows that data products and algorithms are available, and that the technology is ready to be tested for regional applications.","Deep-seated landslide; Early warning systems; Hazard assessment; Machine learning; Remote sensing","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:2150fe82-4347-4e91-9e72-68b2eb06d014","http://resolver.tudelft.nl/uuid:2150fe82-4347-4e91-9e72-68b2eb06d014","Fifty Years of Atmospheric Boundary-Layer Research at Cabauw Serving Weather, Air Quality and Climate","Bosveld, Fred C. (Royal Netherlands Meteorological Institute (KNMI)); Baas, P. (TU Delft Atmospheric Remote Sensing); Beljaars, Anton C.M. (European Centre for Medium Range Forecasting, Reading); Holtslag, Albert A.M. (Wageningen University & Research); de Arellano, Jordi Vilà Guerau (Wageningen University & Research); van de Wiel, B.J.H. (TU Delft Atmospheric Remote Sensing)","","2020","An overview is given of 50-year Cabauw observations and research on the structure and dynamics of the atmospheric boundary layer. It is shown that over time this research site with its 200-m meteorological tower has grown into an atmospheric observatory with a comprehensive observational program encompassing almost all aspects of the atmospheric column including its boundary conditions. This is accomplished by the Cabauw Experimental Site for Atmospheric Research (CESAR) a consortium of research institutes. CESAR plays an important role in the educational programs of the CESAR universities. The current boundary-layer observational program is described in detail, and other parts of the CESAR observational program discussed more briefly. Due to an open data policy the CESAR datasets are used by researchers all over the world. Examples are given of the use of the long time series for model evaluation, satellite validation, and process studies. The role of tall towers is discussed in relation to the development of more and better ground-based remote sensing techniques. CESAR is now incorporated into the Ruisdael observatory, the large-scale atmospheric research infrastructure in the Netherlands. With Ruisdael the embedding of the Dutch atmospheric community in national policy landscape, and in the European atmospheric research infrastructures is assured for the coming decade.","Atmospheric boundary layer; Cabauw atmospheric observatory; Long time records; Remote sensing; Tall towers","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:08ef8be5-732d-4c7c-bec6-2f8d3052a8c0","http://resolver.tudelft.nl/uuid:08ef8be5-732d-4c7c-bec6-2f8d3052a8c0","Importance of Blowing Snow During Cloudy Conditions in East Antarctica: Comparison of Ground-Based and Space-Borne Retrievals Over Ice-Shelf and Mountain Regions","Gossart, Alexandra (Katholieke Universiteit Leuven); Palm, Stephen P. (Science Systems and Applications Inc.; NASA Goddard Space Flight Center); Souverijns, Niels (Katholieke Universiteit Leuven); Lenaerts, Jan T.M. (University of Colorado); Gorodetskaya, Irina V. (University of Aveiro); Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning); van Lipzig, Nicole P.M. (Katholieke Universiteit Leuven)","","2020","Continuous measurements of blowing snow are scarce, both in time and space. Satellites now provide the opportunity to derive blowing snow occurrences, transport and sublimation rates over Antarctica. These products are extremely valuable and offer a continental-wide assessment of blowing snow, which is an important but unknown component of the surface mass balance of the Antarctic ice sheet. However, little ground truth is available to validate these retrievals. The recent application of ceilometers for detection of blowing snow frequencies provides an opportunity to validate the satellite retrievals of blowing snow. A routine to detect blowing snow occurrence from ground-based remote sensing ceilometers has been developed at two coastal locations in East Antarctica for the 2011–2016 time period. Thanks to their ground-based location, ceilometers are able to detect blowing snow events in the presence of clouds and precipitation, which can be missed by the satellite, since optically thick clouds impede the penetration of the signal. In coastal areas, more than 90% of blowing snow occurs under cloudy conditions and represent 30 to 56% of all cloudy conditions at Princess Elisabeth and Neumayer III (Neumayer hereafter) stations, respectively. For cloud-free conditions, 8% of the measurements at Princess Elisabeth (and none at Neumayer) are identified as blowing snow by the satellite but not by the ceilometer, likely due to differences in sensors, limitation of the surface identification by the satellite, or the spatial inhomogeneity of the blowing snow event. While the satellite blowing snow retrieval is a useful product, further investigation is needed to reduce the uncertainties on blowing snow frequencies associated with clouds.","Antarctica; blowing snow; ceilometer; remote sensing; satellite","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:ce55fbc1-a0f7-4357-acde-8e4f2f7f56c2","http://resolver.tudelft.nl/uuid:ce55fbc1-a0f7-4357-acde-8e4f2f7f56c2","Change Detection Algorithm for Multi-Temporal Remote Sensing Images Based on Adaptive Parameter Estimation","Chen, Yu (China University of Geosciences); Ming, Zutao (China University of Geosciences); Menenti, M. (TU Delft Optical and Laser Remote Sensing)","","2020","This paper proposes a multioral image change detection algorithm based on adaptive parameter estimation, which is used to solve the problems of severe interference of coherent speckle noise and the retention of detailed information about changing regions in synthetic aperture radar remote sensing images. The change area in the initial differential image has local consistency and global prominence. By detecting the significant area to locate similar change areas, the coherent speckle noise outside the area can be eliminated. The use of hierarchical FCM clustering to automatically generate training samples can improve the reliability of training samples. In addition, in order to increase the distinction between the changed area and the non-changed area, a sparse automatic encoder is used to extract the changed features and generate a change detection map. Experiments using 4 sets of SAR images show that the algorithm can effectively reduce the effect of speckle noise on detection accuracy, the extraction of changing areas is more complete and meticulous, and the false detection rate is greatly reduced. Since the images in different time phases will be disturbed by weather, clouds, sea water, etc., the target segmentation algorithm can be used to extract the target of interest and highlight the changing area. Principal component analysis and k-means clustering method are used to reduce the influence of isolated pixels, and change information is extracted to obtain different images. The experiment uses four sets of image data of islands and reefs. The experiment proves that the algorithm can well eliminate external interference, improve the accuracy of change detection, and have a good detection effect on the area of islands and reefs. The adaptive parameter estimation plays a good role in the detection of changing areas, and the visual effect is better, which can improve the accuracy of the detection results.","Adaptive parameters; change detection model; multioral; remote sensing images; superficial superposition","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:e13f9284-8850-43a8-8294-126d86d525c6","http://resolver.tudelft.nl/uuid:e13f9284-8850-43a8-8294-126d86d525c6","Rootzone storage capacity reveals drought coping strategies along rainforest-savanna transitions","Singh, C. (TU Delft Water Resources; Stockholm University); Wang-Erlandsson, Lan (Stockholm University); Fetzer, Ingo (Stockholm University); Rockström, Johan (Potsdam Institute for Climate Impact Research); van der Ent, R.J. (TU Delft Water Resources; Universiteit Utrecht)","","2020","Climate change and deforestation have increased the risk of drought-induced forest-to-savanna transitions across the tropics and subtropics. However, the present understanding of forest-savanna transitions is generally focused on the influence of rainfall and fire regime changes, but does not take into account the adaptability of vegetation to droughts by utilizing subsoil moisture in a quantifiable metric. Using rootzone storage capacity (S r), which is a novel metric to represent the vegetation's ability to utilize subsoil moisture storage and tree cover (TC), we analyze and quantify the occurrence of these forest-savanna transitions along transects in South America and Africa. We found forest-savanna transition thresholds to occur around a S r of 550-750 mm for South America and 400-600 mm for Africa in the range of 30%-40% TC. Analysis of empirical and statistical patterns allowed us to classify the ecosystem's adaptability to droughts into four classes of drought coping strategies: lowly water-stressed forest (shallow roots, high TC), moderately water-stressed forest (investing in S r, high TC), highly water-stressed forest (trade-off between investments in S r and TC) and savanna-grassland regime (competitive rooting strategy, low TC). The insights from this study are useful for improved understanding of tropical eco-hydrological adaptation, drought coping strategies, and forest ecosystem regime shifts under future climate change.","Amazon; Congo; ecohydrology; ecosystem dynamics; remote sensing; transects; water-stress","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:a992351f-c72e-4b7f-9162-f625eed0dcdd","http://resolver.tudelft.nl/uuid:a992351f-c72e-4b7f-9162-f625eed0dcdd","Radar remote sensing of wind vector and turbulence intensity fields from raindrop backscattering","Oude Nijhuis, A.C.P. (TU Delft Microwave Sensing, Signals & Systems)","Yarovoy, Alexander (promotor); Russchenberg, H.W.J. (promotor); Krasnov, O.A. (copromotor); Delft University of Technology (degree granting institution)","2019","Scanning radars are promising sensors for atmospheric remote sensing, giving potential to retrieve parameters that characterize the local air dynamics during rain. For the observation of air motion, radars are relying on the backscatter of particles, which can, for example, be raindrops or insects. To measure wind vectors and turbulence intensities remotely during rain the radar is a common choice. This is mainly because the radar signals are not attenuated too much by the rain itself, which is the case for instruments operating at other frequencies, such as lidars. There is, however, a problem with measuring air dynamics from raindrops. Raindrops are not perfect tracers of the air motion. It may thus be necessary to make some corrections when air-dynamics parameters are estimated with a radar during the rain, and account for that raindrops are imperfect tracers of the air motion. This dissertation focuses on this problem. In addition, existing radar-based wind vector and turbulence intensity retrieval techniques are assessed for when they are applied during the rain, and they have been further developed.","Radar; remote sensing; turbulence; wind vectors; rain; inertia effect","en","doctoral thesis","","978-94-6384-004-0","","","","","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:ec90cb5b-99d6-40c0-a3ce-aa0fd478b2f9","http://resolver.tudelft.nl/uuid:ec90cb5b-99d6-40c0-a3ce-aa0fd478b2f9","Automated estimation of link quality for Lora: A remote sensing approach","Demetri, Silvia (Università di Trento); Zuniga, Marco (TU Delft Embedded Systems); Picco, Gian Pietro (Università di Trento); Kuipers, F.A. (TU Delft Embedded Systems); Bruzzone, Lorenzo (Università di Trento); Telkamp, Thomas (Lacuna Space)","Eskicioglu, Rasit (editor)","2019","Many research and industrial communities are betting on LoRa to provide reliable, long-range communication for the Internet of Things. This new radio technology, however, provides widely heterogeneous coverage; a LoRa link may span hundreds of meters or tens of kilometers, depending on the surrounding environment. This high variability is not captured by popular channel models for LoRa, and on-site measurementsÐa common alternativeÐare impractical due to the large geographical areas involved. We propose a novel, automated approach to estimate the coverage of LoRa gateways prior to deployment and without on-site measurements. We achieve this goal by combining free, readily-available multispectral images from remote sensing with the right channel model. Our processing toolchain automatically classifies the type of environment (e.g., buildings, trees, or open fields) traversed by a link, with high accuracy (>90%) and spatial resolution (10×10m2). We use this information to explain the attenuation observed in experiments. As signal attenuation is not well captured by popular channel models, we focus on the Okumura-Hata empirical model, hitherto largely unexplored for LoRa, and show that i) it yields estimates very close to our observations, and ii) we can use our toolchain to automatically select and configure its parameters. A validation on 8,000+ samples from a real dataset shows that our automated approach predicts the expected signal power within a ∼10dBm error, against the 20ś40dBm of popular channel models.","Link quality; LoRa; LPWAN; Multispectral images; Remote sensing","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Embedded Systems","","",""
"uuid:cdf7f648-37aa-41dc-b983-4ab430798c9f","http://resolver.tudelft.nl/uuid:cdf7f648-37aa-41dc-b983-4ab430798c9f","Velocity-Based EDR Retrieval Techniques Applied to Doppler Radar Measurements from Rain: Two Case Studies","Oude Nijhuis, A.C.P. (TU Delft Microwave Sensing, Signals & Systems); Unal, C.M.H. (TU Delft Atmospheric Remote Sensing); Krasnov, O.A. (TU Delft Microwave Sensing, Signals & Systems); Russchenberg, H.W.J. (TU Delft Geoscience and Remote Sensing); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2019","In this article, five velocity-based energy dissipation rate (EDR) retrieval techniques are assessed. The EDR retrieval techniques are applied to Doppler measurements from Transportable Atmospheric Radar (TARA)—a precipitation profiling radar—operating in the vertically fixed-pointing mode. A generalized formula for the Kolmogorov constant is derived, which gives potential for the application of the EDR retrieval techniques to any radar line of sight (LOS). Two case studies are discussed that contain rain events of about 2 and 18 h, respectively. The EDR values retrieved from the radar are compared to in situ EDR values from collocated sonic anemometers. For the two case studies, a correlation coefficient of 0.79 was found for the wind speed variance (WSV) EDR retrieval technique, which uses 3D wind vectors as input and has a total sampling time of 10 min. From this comparison it is concluded that the radar is able to measure EDR with a reasonable accuracy. Almost no correlation was found for the vertical wind velocity variance (VWVV) EDR retrieval technique, as it was not possible to sufficiently separate the turbulence dynamics contribution to the radar Doppler mean velocities from the velocity contribution of falling raindrops. An important cause of the discrepancies between radar and in situ EDR values is thus due to insufficient accurate estimation of vertical air velocities.","Radar observations; Radars; Rainfall; Remote sensing; Turbulence; Weather radar signal processing","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","","","Geoscience and Remote Sensing","Microwave Sensing, Signals & Systems","","",""
"uuid:ae86c8b5-1ead-4f2e-a498-aadfee340022","http://resolver.tudelft.nl/uuid:ae86c8b5-1ead-4f2e-a498-aadfee340022","Impact of soil moisture data resolution on soil moisture and surface heat flux estimates through data assimilation: A case study in the Southern Great Plains","Lu, Y. (TU Delft Water Resources); Dong, Jianzhi (USDA-ARS Hydrology and Remote Sensing Laboratory); Steele-Dunne, S.C. (TU Delft Water Resources)","","2019","The spatial heterogeneity and temporal variation of soil moisture and surface heat fluxes are key to many geophysical and environmental studies. It has been demonstrated that they can be mapped by assimilating soil thermal and wetness information into surface energy balance models. The aim of this work is to determine whether enhancing the spatial resolution or temporal sampling frequency of soil moisture data could improve soil moisture or surface heat flux estimates. Two experiments are conducted in an area mainly covered by grassland, and land surface temperature (LST) observations from the Geostationary Operational Environmental Satellite (GOES) mission are assimilated together with either an enhanced L-band passive soil moisture product (9 km, 2-3 days) from the Soil Moisture Active Passive (SMAP) mission or a merged product (36 km, quasi-daily) from the SMAP and the Soil Moisture Ocean Salinity (SMOS) mission. The results suggest that the availability of soil moisture observations is increased by 41% after merging data from the SMAP and the SMOS missions. A comparison with results from a previous study that assimilated a coarser SMAP soil moisture product (36 km, 2-3 days) suggests that enhancing the temporal sampling frequency of soil moisture observations leads to improved soil moisture estimates at both the surface and root zone, and the largest improvement is seen in the bias metric (0.008 and 0.007m 3 m -3 on average at the surface and root zone, respectively). Enhancing the spatial resolution, however, does not significantly improve soil moisture estimates, particularly at the surface. Surface heat flux estimates from assimilating soil moisture data of different spatial or temporal resolutions are very similar.","Atmosphere-land interaction; Data assimilation; Energy budget/balance; Remote sensing; Soil moisture; Surface temperature","en","journal article","","","","","","","","2019-10-25","","","Water Resources","","",""
"uuid:338c74ab-c3dd-443d-aa83-7a68f1e6084c","http://resolver.tudelft.nl/uuid:338c74ab-c3dd-443d-aa83-7a68f1e6084c","Comparing thresholding with machine learning classifiers for mapping complex water","Bangira, T. (TU Delft Optical and Laser Remote Sensing; Stellenbosch University); Alfieri, S.M. (TU Delft Optical and Laser Remote Sensing); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); van Niekerk, Adriaan (Stellenbosch University)","","2019","Small reservoirs play an important role in mining, industries, and agriculture, but storage levels or stage changes are very dynamic. Accurate and up-to-date maps of surface water storage and distribution are invaluable for informing decisions relating to water security, flood monitoring, and water resources management. Satellite remote sensing is an effective way of monitoring the dynamics of surface waterbodies over large areas. The European Space Agency (ESA) has recently launched constellations of Sentinel-1 (S1) and Sentinel-2 (S2) satellites carrying C-band synthetic aperture radar (SAR) and a multispectral imaging radiometer, respectively. The constellations improve global coverage of remotely sensed imagery and enable the development of near real-time operational products. This unprecedented data availability leads to an urgent need for the application of fully automatic, feasible, and accurate retrieval methods for mapping and monitoring waterbodies. The mapping of waterbodies can take advantage of the synthesis of SAR and multispectral remote sensing data in order to increase classification accuracy. This study compares automatic thresholding to machine learning, when applied to delineate waterbodies with diverse spectral and spatial characteristics. Automatic thresholding was applied to near-concurrent normalized difference water index (NDWI) (generated from S2 optical imagery) and VH backscatter features (generated from S1 SAR data). Machine learning was applied to a comprehensive set of features derived from S1 and S2 data. During our field surveys, we observed that the waterbodies visited had different sizes and varying levels of turbidity, sedimentation, and eutrophication. Five machine learning algorithms (MLAs), namely decision tree (DT), k-nearest neighbour (k-NN), random forest (RF), and two implementations of the support vector machine (SVM) were considered. Several experiments were carried out to better understand the complexities involved in mapping spectrally and spatially complex waterbodies. It was found that the combination of multispectral indices with SAR data is highly beneficial for classifying complex waterbodies and that the proposed thresholding approach classified waterbodies with an overall classification accuracy of 89.3%. However, the varying concentrations of suspended sediments (turbidity), dissolved particles, and aquatic plants negatively affected the classification accuracies of the proposed method, whereas the MLAs (SVM in particular) were less sensitive to such variations. The main disadvantage of using MLAs for operational waterbody mapping is the requirement for suitable training samples, representing both water and non-water land covers. The dynamic nature of reservoirs (many reservoirs are depleted at least once a year) makes the re-use of training data unfeasible. The study found that aggregating (combining) the thresholding results of two SAR and multispectral features, namely the S1 VH polarisation and the S2 NDWI, respectively, provided better overall accuracies than when thresholding was applied to any of the individual features considered. The accuracies of this dual thresholding technique were comparable to those of machine learning and may thus offer a viable solution for automatic mapping of waterbodies.","Machine learning; Optically complex; Remote sensing; Sentinel-1; Sentinel-2; Thresholding; Waterbody mapping","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:418c7592-be9c-4d6c-bc38-da9b7421f576","http://resolver.tudelft.nl/uuid:418c7592-be9c-4d6c-bc38-da9b7421f576","Sugarcane productivity mapping through C-band and L-band SAR and optical satellite imagery","Molijn, R.A. (TU Delft Mathematical Geodesy and Positioning); Iannini, L. (TU Delft Optical and Laser Remote Sensing); Rocha, Jansle Vieira (University of Campinas); Hanssen, R.F. (TU Delft Mathematical Geodesy and Positioning)","","2019","Space-based remote sensing imagery can provide a valuable and cost-effective set of observations for mapping crop-productivity differences. The effectiveness of such signals is dependent on several conditions that are related to crop and sensor characteristics. In this paper, we present the dynamic behavior of signals from five Synthetic Aperture Radar (SAR) sensors and optical sensors with growing sugarcane, focusing on saturation effects and the influence of precipitation events. In addition, we analyzed the level of agreement within and between these spaceborne datasets over space and time. As a result, we produced a list of conditions during which the acquisition of satellite imagery is most effective for sugarcane productivity monitoring. For this, we analyzed remote sensing data from two C-band SAR (Sentinel-1 and Radarsat-2), one L-band SAR (ALOS-2), and two optical sensors (Landsat-8 and WorldView-2), in conjunction with detailed ground-reference data acquired over several sugarcane fields in the state of São Paulo, Brazil. We conclude that satellite imagery from L-band SAR and optical sensors is preferred for monitoring sugarcane biomass growth in time and space. Additionally, C-band SAR imagery offers the potential for mapping spatial variations during specific time windows and may be further exploited for its precipitation sensitivity.","Precipitation effects; SAR and optical remote sensing; Saturation effects; Sugarcane growth monitoring","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:f7fa190e-111d-4cbc-a5b5-e208eb02b6fc","http://resolver.tudelft.nl/uuid:f7fa190e-111d-4cbc-a5b5-e208eb02b6fc","Detecting the response of irrigation water management to climate by remote sensing monitoring of evapotranspiration","El Ghandour, F.E. (TU Delft Optical and Laser Remote Sensing; Chouaib Doukkali University); Alfieri, S.M. (TU Delft Optical and Laser Remote Sensing); Houali, Youssef (Chouaib Doukkali University); Habib, Adnane (Chouaib Doukkali University; Chinese Academy of Sciences); Akdim, Nadia (Chouaib Doukkali University); Labbassi, Kamal (Chouaib Doukkali University); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences)","","2019","This study on a large irrigation scheme in Morocco addressed a two-fold question: (a) does the local water management authority adapt water releases to atmospheric water demand ET0-P? and (b) does crop actual evapotranspiration respond to inter- and intra-annual variability in water releases? We have evaluated the inter-annual variability of ET0-P during the period 1992-2017 and compared its anomalies (i.e., deviations from average) with anomalies in annual water release. Overall, it appeared that anomalies in water release were consistent with anomalies in ET0-P. The actual evapotranspiration (ETa) was estimated using a time series of multi-spectral satellite image data by applying the Surface Energy Balance (SEBAL) algorithm in a dry, wet, and reference year. We have determined the quartiles of the distribution of the ET0-P time series to identify these three years. The dry year was 2015-2016, the wet year was 2014-2015, and the reference (median of ET0-P) was 2013-2014. Finally, we compared seasonal and annual anomalies in ET0-P, ETa and release, Wd of irrigation water. In the period 1992-2017, the relative anomalies in ET0-P and Wd were similar only in 2000-2001 and 2015-2016. The analysis of anomalies in water inflow and stocks confirmed the response in increased Wd following wet years with higher inflow and replenishment of the reservoir. The response of crop water use to the irrigation water supply was evaluated by comparing anomalies in the ratio of actual to maximum ET, i.e., ETa/ETc with anomalies in Wd. As regards the Sidi Bennour, Faregh, and Gharbia districts, the relative anomalies in ETa/ETc and Wd were consistent, i.e., they had the same sign and comparable magnitude. Overall, the study shows that water delivery Wd responds to inter-annual variability in the pre-irrigation season water inflows into the reservoirs, rather than in ET0-P. On the other hand, actual crop water use, i.e., ETa/ETc, does respond to inter- and intra-annual variability in Wd. This evidence suggests that there is scope for adaptive water management based on a flexible adaptation of water release to inter- and intra-annual variability in water demand.","Actual evapotranspiration; Adaptive water management; Atmospheric water demand; Remote sensing","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:0cff7298-14a7-4a3c-8d74-c178405a2ee5","http://resolver.tudelft.nl/uuid:0cff7298-14a7-4a3c-8d74-c178405a2ee5","Maximizing Water--Food--Energy Nexus Synergies at Basin Scale","Burger, Rogier (Student TU Delft); Abraham, E. (TU Delft Water Resources)","Naddeo, V. (editor); Balakrishnan, M. (editor); Choo, K.H. (editor)","2019","In this short paper, we show how solutions for mitigating resource security in one sector can be found in another. We demonstrate—by means of a case study in Burkina Faso and Ghana—how investing in the electricity grid in the south leads to increase food security in the north. A new nexus framework was developed (‘MAXUS’) which was built to understand, simulate and optimize intersectoral (and international) development strategies in the water, food and energy sectors. We believe this new type of geospatial integral resource management, supported by the exponential increase of data availability of the twenty-first century, could finally turn nexus models into decision support tools.","Nexus optimization framework; Bottom-up approach; Integrated resource management; Remote sensing","en","book chapter","Springer","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2020-03-19","","","Water Resources","","",""
"uuid:6d5bb44f-9ed6-4d5b-97df-a4573d9bb754","http://resolver.tudelft.nl/uuid:6d5bb44f-9ed6-4d5b-97df-a4573d9bb754","From global goals to local gains—a framework for crop water productivity","Blatchford, Megan Leigh (University of Twente); Karimi, Poolad (IHE Delft Institute for Water Education); Bastiaanssen, W.G.M. (TU Delft Water Resources; IHE Delft Institute for Water Education); Nouri, Hamideh (University of Twente; University of Göttingen)","","2018","Crop water productivity (CWP) has become a recognised indicator in assessing the state of Sustainable Development Goals (SDG) 6.4—to substantially increase water use efficiency. This indicator, while useful at a global scale, is not comprehensive at a local scale. To fill this gap, this research proposes a CWP framework, that takes advantage of the spatio-temporal availability of remote sensing, that identifies CWP goals and sub-indicators specific to the needs of the targeted domain. Three sub-indicators are considered; (i) a global water productivity score (GWPS), (ii) a local water productivity score (LWPS) and (iii) a land and water use productivity score (YWPS). The GWPS places local CWP in the global context and focuses on maximised CWP. The LWPS differentiates yield zones, normalising for potential product, and focuses on minimising water consumption. The YWPS focuses simultaneously on improving land and water productivity equally. The CWP framework was applied to potato in the West Bank, Palestine. Three management practices were compared under each sub-indicator. The case study showed that fields with high and low performance were different under each sub-indicator. The performance associated with different management practices was also different under each sub-indicator. For example, a winter rotation had a higher performance under the YWPS, the fall rotation had a higher performance under the LWPS and under the GWPS there was little difference. The results showed, that depending on the basin goal, not only do the sub-indicators required change, but also the management practices or approach required to reach those basin goals. This highlights the importance of providing a CWP framework with multiple sub-indicators, suitable to basin needs, to ensure that meeting the SDG 6.4 goal does not jeopardise local objectives.","Evapotranspiration; Indicators; Palestine; Potato; Remote sensing; Surface Energy Balance Algorithm for Land (SEBAL); Sustainable development goals (SDGs); Yield","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:80c62d6f-0ae0-4e96-9554-841ddcd506c0","http://resolver.tudelft.nl/uuid:80c62d6f-0ae0-4e96-9554-841ddcd506c0","Global Mapping of Atmospheric Composition from Space: Retrieving Aerosol Height and Tropospheric NO2 from OMI","Chimot, J.J. (TU Delft Atmospheric Remote Sensing)","Levelt, Pieternel Felicitas (promotor); Veefkind, j. Pepijn (copromotor); Delft University of Technology (degree granting institution)","2018","The main objective of this thesis is to design a new aerosol layer height retrieval in order to improve the operational NO2 retrieval, both in the troposphere, from space-borne instruments for highly polluted events and under cloud-free conditions. This thesis focuses on the exploitation of the OMI satellite measurements acquired in the visible wavelength range (405-490 nm). In addition, we develop numerical methods and tools (e.g. machine learning) in order to support the operational processing of big data amounts from the forthcoming new-generation satellite instruments for air quality and climate research.","trace gas; aerosol; cloud; air quality; climate; satellite remote sensing; atmospheric retrieval; spectral signature; radiation scattering; absorption","en","doctoral thesis","","978-94-6366-010-5","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:f5634c57-2468-4b10-ae6f-0776ca8bff07","http://resolver.tudelft.nl/uuid:f5634c57-2468-4b10-ae6f-0776ca8bff07","Subsidence in the Dutch Wadden Sea","Fokker, Peter A. (TNO; Universiteit Utrecht); van Leijen, F.J. (TU Delft Mathematical Geodesy and Positioning); Orlic, Bogdan (TNO); van der Marel, H. (TU Delft Mathematical Geodesy and Positioning); Hanssen, R.F. (TU Delft Mathematical Geodesy and Positioning)","","2018","Ground surface dynamics is one of the processes influencing the future of the Wadden Sea area. Vertical land movement, both subsidence and heave, is a direct contributor to changes in the relative sea level. It is defined as the change of height of the Earth's surface with respect to a vertical datum. In the Netherlands, The Normaal Amsterdams Peil (NAP) is the official height datum, but its realisation via reference benchmarks is not time-dependent. Consequently, NAP benchmarks are not optimal for monitoring physical processes such as land subsidence. However, surface subsidence can be regarded as a differential signal: The vertical motion of one location relative to the vertical motion of another location. In this case, the actual geodetic height datum is superfluous. In the present paper, we highlight the processes that cause subsidence, with specific focus on the Wadden Sea area. The focus will be toward anthropogenic causes of subsidence, and how to understand them; how to measure and monitor and use these measurements for better characterisation and forecasting; with some details on the activities in the Wadden Sea that are relevant in this respect. This naturally leads to the identification of knowledge gaps and to the formulation of notions for future research.","inversion; remote sensing; subsidence; Wadden Sea","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:243d3f23-eca8-4a3c-a0fd-414d68b811b9","http://resolver.tudelft.nl/uuid:243d3f23-eca8-4a3c-a0fd-414d68b811b9","Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives","Boers, Reinout (Royal Netherlands Meteorological Institute (KNMI)); Knist, Christine (Deutscher Wetterdienst); Russchenberg, H.W.J. (TU Delft Geoscience and Remote Sensing); Werner, Frank (Joint Center for Earth Systems Technology); Wood, Robert (University of Washington); Zhang, Zhibo (CRESST and University of Maryland); Quaas, Johannes (University of Leipzig)","","2018","The cloud droplet number concentration (Nd) is of central interest to improve the understanding of cloud physics and for quantifying the effective radiative forcing by aerosol-cloud interactions. Current standard satellite retrievals do not operationally provide Nd, but it can be inferred from retrievals of cloud optical depth (τc) cloud droplet effective radius (re) and cloud top temperature. This review summarizes issues with this approach and quantifies uncertainties. A total relative uncertainty of 78% is inferred for pixel-level retrievals for relatively homogeneous, optically thick and unobscured stratiform clouds with favorable viewing geometry. The uncertainty is even greater if these conditions are not met. For averages over 1° ×1° regions the uncertainty is reduced to 54% assuming random errors for instrument uncertainties. In contrast, the few evaluation studies against reference in situ observations suggest much better accuracy with little variability in the bias. More such studies are required for a better error characterization. Nd uncertainty is dominated by errors in re, and therefore, improvements in re retrievals would greatly improve the quality of the Nd retrievals. Recommendations are made for how this might be achieved. Some existing Nd data sets are compared and discussed, and best practices for the use of Nd data from current passive instruments (e.g., filtering criteria) are recommended. Emerging alternative Nd estimates are also considered. First, new ideas to use additional information from existing and upcoming spaceborne instruments are discussed, and second, approaches using high-quality ground-based observations are examined.","cloud droplet concentrations; lidar; passive retrievals; radar; remote sensing; satellite","en","journal article","","","","","","","","","","Geoscience and Remote Sensing","","","",""
"uuid:cfbb6d08-2bb7-4831-b957-18587869ef34","http://resolver.tudelft.nl/uuid:cfbb6d08-2bb7-4831-b957-18587869ef34","Sensitivity of rip current forecasts to errors in remotely-sensed bathymetry","Radermacher, M. (TU Delft Coastal Engineering; WaveDroid); de Schipper, M.A. (TU Delft Coastal Engineering; Shore Monitoring & Research); Reniers, A.J.H.M. (TU Delft Environmental Fluid Mechanics)","","2018","Operational nearshore current forecasts based on numerical model simulations are gaining popularity as a measure to increase the safety of swimmers. Applying remotely-sensed bathymetry in these model simulations is often proposed in order to cope with rapidly changing nearshore bathymetry. Errors in the remotely-sensed bathymetry may negatively affect performance of the hydrodynamic model. Hence, this study aims to determine the sensitivity of modelled nearshore currents (with a strong focus on rip currents) to errors in remotely-sensed bathymetries. The errors in the remotely-sensed bathymetries (depth inversion algorithm applied to video stream) were quantified with a length scale-aware validation technique, providing useful insights in the contribution of pattern and amplitude errors to the total error throughout the analysis domain and over a range of bathymetric length scales. Subsequently, simulations with a nearshore hydrodynamic model were performed, using both in-situ and remotely-sensed bathymetries as an input. A comparison of predicted rip currents on either bathymetry yielded performance statistics for operational current forecasts on remotely-sensed bathymetries, taking the model with in-situ bathymetry as a reference. Linking these performance statistics back to the quantified errors in the remotely-sensed bathymetry finally revealed the relation between errors in flow and bathymetry. Of all rip currents generated on an in-situ bathymetry, 55% were reproduced on the remotely-sensed bathymetry, showing that models predicting nearshore currents on remotely-sensed bathymetry have predictive value. Positive rip current predictions were promoted significantly by accurate reproduction of the pattern and amplitude of nearshore bars at length scales between 200 and 400 m. In contrast to the length-scale aware validation technique applied here, commonly used domain-wide bulk error metrics lack important information about spatial variations in the quality of remotely-sensed bathymetry.","Depth inversion; Numerical modeling; Remote sensing; Rip currents; Sand motor; Swimmer safety","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2018-08-03","","","Coastal Engineering","","",""
"uuid:31e1dd88-4d43-4e8f-92fc-f39c61922dd4","http://resolver.tudelft.nl/uuid:31e1dd88-4d43-4e8f-92fc-f39c61922dd4","Adaptive and high-resolution estimation of specific differential phase for polarimetric X-band weather radars","Reinoso Rondinel, R. (TU Delft Atmospheric Remote Sensing); Unal, C.M.H. (TU Delft Atmospheric Remote Sensing); Russchenberg, H.W.J. (TU Delft Geoscience and Remote Sensing)","","2018","One of the most beneficial polarimetric variables may be the specific differential phase KDP because of its independence from power attenuation and radar miscalibration. However, conventional KDP estimation requires a substantial amount of range smoothing as a result of the noisy characteristic of the measured differential phase ψDP. In addition, the backscatter differential phase δhv component of ψDP, significant at C- and X-band frequency, may lead to inaccurate KDP estimates. In this work, an adaptive approach is proposed to obtain accurate KDP estimates in rain from noisy ψDP, whose δhv is of significance, at range resolution scales. This approach uses existing relations between polarimetric variables in rain to filter δhv from ψDP while maintaining its spatial variability. In addition, the standard deviation of the proposed KDP estimator is mathematically formulated for quality control. The adaptive approach is assessed using four storm events, associated with light and heavy rain, observed by a polarimetric X-band weather radar in the Netherlands. It is shown that this approach is able to retain the spatial variability of the storms at scales of the range resolution. Moreover, the performance of the proposed approach is compared with two different methods. The results of this comparison show that the proposed approach outperforms the other two methods in terms of the correlation between KDP and reflectivity, and KDP standard deviation reduction.","Data processing; Filtering techniques; Radars/Radar observations; Remote sensing; Weather radar signal processing","en","journal article","","","","","","","","2019-04-30","","Geoscience and Remote Sensing","Atmospheric Remote Sensing","","",""
"uuid:3d0d456d-c6a9-4781-9a18-6cb041a4fd03","http://resolver.tudelft.nl/uuid:3d0d456d-c6a9-4781-9a18-6cb041a4fd03","Satellite-derived NOx emissions over East Asia","Ding, J. (TU Delft Atmospheric Remote Sensing)","Levelt, Pieternel Felicitas (promotor); van der A, Ronald (copromotor); Delft University of Technology (degree granting institution)","2018","Nitrogen oxides (NOx) are important air pollutants and play a crucial role in climate change. NOx emissions are important for chemical transport models to simulate and forecast air quality. Up-to-date emission information also helps policymakers to mitigate air pollution. In this thesis, we have focused on providing better NOx emission estimates with the DECSO (Daily Emission estimates Constrained by Satellite Observations) inversion algorithm applied to satellite observations. DECSO is a fast algorithm, which enables daily emissions estimates as soon as the satellite observations are available. Satellite-derived emissions reveal more specific information on the location and strength of sources than concentration observations. The monthly and yearly variability in emissions are well captured. This is demonstrated by our monitoring of the effect of air quality regulations on emissions during events like the 2014 Youth Olympic Games. Near the Chinese coast ship tracks, which are otherwise hidden under the outflow of air pollution from the mainland, are revealed in our NOx emissions derived with DECSO applied to OMI satellite observations. Trends of shipping emissions for a 10-year period (2007 to 2016) over Chinese seas are presented for the first time.","Air Quality; Remote sensing","en","doctoral thesis","","978-94-6366-006-8","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:a56ea0b2-2010-4961-906e-0a544a4f77d2","http://resolver.tudelft.nl/uuid:a56ea0b2-2010-4961-906e-0a544a4f77d2","Integration of satellite remote sensing data in ecosystem modelling at local scales: Practices and trends","Pasetto, Damiano (Swiss Federal Institute of Technology); Arenas-Castro, Salvador (Universidade do Porto); Bustamante, Javier (University of the Balearic Islands); Casagrandi, Renato (Politecnico di Milano); Chrysoulakis, Nektarios (Foundation for Research and Technology - Hellas (FORTH)); Cord, Anna F. (Helmholtz Centre for Environmental Research - UFZ); Dittrich, Andreas (Helmholtz Centre for Environmental Research - UFZ); Domingo‐Marimon, Cristina (Universitat Autònoma de Barcelona); El Serafy, G.Y.H. (TU Delft Mathematical Physics; Deltares); Karnieli, Arnon (Ben-Gurion University of the Negev); Kordelas, Georgios A. (Centre for Research and Technology-Hellas); Manakos, Ioannis (Centre for Research and Technology-Hellas); Mari, Lorenzo (Politecnico di Milano); Monteiro, Antonio (Universidade do Porto); Palazzi, Elisa (Institute of Atmospheric Sciences and Climate of the National Research Council); Poursanidis, Dimitris (Foundation for Research and Technology - Hellas (FORTH)); Rinaldo, Andrea (École Polytechnique de Lausanne; Università degli Studi di Padova); Terzago, Silvia (Institute of Atmospheric Sciences and Climate of the National Research Council); Ziemba, A.M. (TU Delft Mathematical Physics; Deltares); Ziv, Guy (University of Leeds)","","2018","Spatiotemporal ecological modelling of terrestrial ecosystems relies on climatological and biophysical Earth observations. Due to their increasing availability, global coverage, frequent acquisition and high spatial resolution, satellite remote sensing (SRS) products are frequently integrated to in situ data in the development of ecosystem models (EMs) quantifying the interaction among the vegetation component and the hydrological, energy and nutrient cycles. This review highlights the main advances achieved in the last decade in combining SRS data with EMs, with particular attention to the challenges modellers face for applications at local scales (e.g. small watersheds). We critically review the literature on progress made towards integration of SRS data into terrestrial EMs: (1) as input to define model drivers; (2) as reference to validate model results; and (3) as a tool to sequentially update the state variables, and to quantify and reduce model uncertainty. The number of applications provided in the literature shows that EMs may profit greatly from the inclusion of spatial parameters and forcings provided by vegetation and climatic-related SRS products. Limiting factors for the application of such models to local scales are: (1) mismatch between the resolution of SRS products and model grid; (2) unavailability of specific products in free and public online repositories; (3) temporal gaps in SRS data; and (4) quantification of model and measurement uncertainties. This review provides examples of possible solutions adopted in recent literature, with particular reference to the spatiotemporal scales of analysis and data accuracy. We propose that analysis methods such as stochastic downscaling techniques and multi-sensor/multi-platform fusion approaches are necessary to improve the quality of SRS data for local applications. Moreover, we suggest coupling models with data assimilation techniques to improve their forecast abilities. This review encourages the use of SRS data in EMs for local applications, and underlines the necessity for a closer collaboration among EM developers and remote sensing scientists. With more upcoming satellite missions, especially the Sentinel platforms, concerted efforts to further integrate SRS into modelling are in great demand and these types of applications will certainly proliferate.","data assimilation; ecohydrological models; satellite remote sensing; stochastic downscaling","en","review","","","","","","","","","","","Mathematical Physics","","",""
"uuid:74b25581-c42c-423b-a6a9-7dc69b5a0e8c","http://resolver.tudelft.nl/uuid:74b25581-c42c-423b-a6a9-7dc69b5a0e8c","A New Model Proposal for Integrated Satellite Constellation Scheduling within a Planning Horizon given Operational Constraints","Pinto, M.J. (TU Delft Safety and Security Science; TNO; Institute of Advanced Studies, São José dos Campos); Barros, A.I. (TNO); Noomen, R. (TU Delft Astrodynamics & Space Missions); van Gelder, P.H.A.J.M. (TU Delft Safety and Security Science); Lamballais Tessensohn, T (TNO)","","2018","The operational use of satellite systems has been increasing due to technological advances and the reduced costs of satellites and their launching. As such it has become more relevant to determine how to better use these new capabilities which is reflected in an increase in application studies in this area. This work focuses on the problem of developing the scheduling of a constellation of satellites and associated ground stations to monitor different types of locations (targets) with different priorities for a given planning horizon. In order to address this problem we will propose a new model that considers explicitly the operational requirements of Brazilian relevant scenarios for a given planning horizon and target priority list. The methodology to be developed to solve this model will also be discussed.","Scheduling; Satellite Constellation; Optimization Model; Operational Scenarios; Remote Sensing","en","conference paper","","","","","","","","","","","Safety and Security Science","","",""
"uuid:7e49dce0-1394-4b59-aea5-c61e9b395873","http://resolver.tudelft.nl/uuid:7e49dce0-1394-4b59-aea5-c61e9b395873","Constraining Conceptual Hydrological Models With Multiple Information Sources","Nijzink, R.C. (TU Delft Water Resources; Luxembourg Institute of Science and Technology); Almeida, S. (University of Bristol; University of Leeds); Pechlivanidis, I. G. (Swedish Meteorological and Hydrological Institute); Capell, R. (Swedish Meteorological and Hydrological Institute); Gustafssons, D. (Swedish Meteorological and Hydrological Institute); Arheimer, B. (Swedish Meteorological and Hydrological Institute); Parajka, J. (Technische Universität Wien); Freer, J. (University of Bristol); Han, D. (University of Bristol); Wagener, T. (University of Bristol); van Nooijen, R.R.P. (TU Delft Water Resources); Savenije, Hubert (TU Delft Water Resources); Hrachowitz, M. (TU Delft Water Resources)","","2018","The calibration of hydrological models without streamflow observations is problematic, and the simultaneous, combined use of remotely sensed products for this purpose has not been exhaustively tested thus far. Our hypothesis is that the combined use of products can (1) reduce the parameter search space and (2) improve the representation of internal model dynamics and hydrological signatures. Five different conceptual hydrological models were applied to 27 catchments across Europe. A parameter selection process, similar to a likelihood weighting procedure, was applied for 1,023 possible combinations of 10 different data sources, ranging from using 1 to all 10 of these products. Distances between the two empirical distributions of model performance metrics with and without using a specific product were determined to assess the added value of a specific product. In a similar way, the performance of the models to reproduce 27 hydrological signatures was evaluated relative to the unconstrained model. Significant reductions in the parameter space were obtained when combinations included Advanced Microwave Scanning Radiometer - Earth Observing System and Advanced Scatterometer soil moisture, Gravity Recovery and Climate Experiment total water storage anomalies, and, in snow-dominated catchments, the Moderate Resolution Imaging Spectroradiometer snow cover products. The evaporation products of Land Surface Analysis - Satellite Application Facility and MOD16 were less effective for deriving meaningful, well-constrained posterior parameter distributions. The hydrological signature analysis indicated that most models profited from constraining with an increasing number of data sources. Concluding, constraining models with multiple data sources simultaneously was shown to be valuable for at least four of the five hydrological models to determine model parameters in absence of streamflow.","calibration; hydrological modeling; parameter estimation; remote sensing; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:46f0b6e6-5592-4b05-983b-a04c8f0f88a8","http://resolver.tudelft.nl/uuid:46f0b6e6-5592-4b05-983b-a04c8f0f88a8","Water stress detection using radar","van Emmerik, T.H.M. (TU Delft Water Resources)","van de Giesen, N.C. (promotor); Steele-Dunne, S.C. (copromotor); Delft University of Technology (degree granting institution)","2017","Vegetation is a crucial part of the water and carbon cycle. Through photosynthesis carbon is assimilated for biomass production, and oxygen is released into the atmosphere. During this process, water is transpired through the stomata, and is redistributed in the plant. Transpired water is refilled by uptake of water from the root zone in the subsurface. Transpiration by vegetation accounts for most of the total evaporation from land on a global scale. In some ecosystems, such as tropical rainforests, transpiration even makes up more than 70% of total evaporation.
Periods of low water availability, water stress, leads to irreversible damage to plants, and can eventually lead to plant death. To prevent this, various mechanisms are activated by the vegetation to survive. Transpiration is reduced as a result of vegetation water stress, which can affect the water and carbon cycle on local, regional, and even global scales. Additionally, water stress in crops is one of the major reasons for harvest losses, threatening food security. However, many effects of vegetation water stress on crops and tropical forests remains poorly understood.
New satellite observations provide opportunities for better detection and understanding of vegetation water stress. Recent research suggests that radar remote sensing might yield valuable insights into vegetation water content. Radar backscatter is sensitive to vegetation because of direct backscatter from the canopy, and through two-way attenuation of the signal as it travels through the vegetation layer. The degree of interaction of radar waves with the vegetation is mainly a function of the vegetation dielectric constant, which is in turn primarily influenced by vegetation water content.
Over the last years, various studies have reported links between anomalies in radar backscatter and vegetation water stress. This has led to the hypothesis that radar backscatter is sensitive to vegetation water stress. Additional field measurements of vegetation water content and dielectric constant, in combination with radar backscatter are necessary to test this hypothesis. This is what inspired this thesis. Based on a combination of field measurements using new sensors, models, and radar backscatter, this thesis focuses on understanding the effects of water stress on plant dynamics, identifying early signatures of vegetation water stress, and exploring the opportunities of early water stress detection using radar remote sensing.
This thesis studies the effects of vegetation water stress across scales, from individual leaves to rainforests. A new method is presented that allows measurements of leaf dielectric properties on living plants. First, the method is tested on tomato plants in a controlled environment. By measuring tomato plants with and without water stress, it is demonstrated that there is a significant difference in the leaf dielectric properties of stressed and unstressed tomato plants. Second, this same method is used under field conditions. Using data sets of corn plants with and without water stress, it is demonstrated that water stress changes plant water content, resulting in significant changes of leaf dielectric properties. Using the field data from the stressed corn field, a modeling study was done to investigate the sensitivity of radar backscatter to water stress. Here, it is shown that total and leaf water content can change considerably during the day, leading to observable differences in radar backscatter.
To study the effects of water stress in tropical rainforests, accelerometers were placed on trees in the Brazilian Amazon to measure tree sway. Tree sway depends on various tree properties, and this thesis demonstrates that the measured tree acceleration is sensitive to tree mass, intercepted rainfall, and tree-atmosphere interactions. Using five months of acceleration data from 19 trees, an effect of the transition from the wet to the dry season was found. This thesis hypothesizes that this was caused by water related changes in tree mass, or leaf fall in response to increased tree water deficit.
Finally, coinciding field data on tree water content and tree water deficit, and radar backscatter, were used to demonstrate the sensitivity of radar backscatter to increased water stress. During the transition from wet to dry season, a strong drop was found in radar backscatter, which is explained by a rapid increase in measured tree water deficit.
For years, the hypothesis that radar backscatter is sensitive to vegetation water stress has been discussed. Yet, a lack of observations withheld this hypothesis to be tested. This thesis uses field data of crops, and trees in tropical forests, and modeling approaches to finally demonstrate that vegetation water stress results in significant changes in plant water status, which lead to observable variations in radar backscatter.","radar; vegetation; water stress; hydrology; amazon; maize; corn; rainforest; tomato; dielectric constant; dielectric properties; remote sensing","en","doctoral thesis","","978-90-6824-060-3","","","","","","","","","Water Resources","","",""
"uuid:66da67a6-cf90-4a71-822e-3d27d0e7ec8d","http://resolver.tudelft.nl/uuid:66da67a6-cf90-4a71-822e-3d27d0e7ec8d","Applications of passive microwave data to monitor inundated areas and model stream flow","Shang, H. (TU Delft Optical and Laser Remote Sensing)","Menenti, M. (promotor); Jia, L. (promotor); Steele-Dunne, S.C. (copromotor); Delft University of Technology (degree granting institution)","2017","The observation of surface water bodies in all weather conditions and better knowledge about inundation patterns are important for water resource management and flood early warning. Microwave radiometers at 37 GHz were applied to observe and study the inundation pattern in large subtropical floodplains in China, i.e. the Poyang Lake and Dongting Lake floodplains, due to the trade-off between the capability to penetrate hydrometeors and vegetation, revisiting time, and spatial coverage and resolution. Taking the shallow sensing depth at 37 GHz into account, open water, inundated area and water saturated soil surface all determine the surface emittance measured by the radiometer. Thus, Water Saturated Surface (WSS) is defined as the combination of these three land surface elements.
In subtropical regions, seasonal changes in vegetation cover and various surface roughness conditions are the major challenges for the observation of surface water bodies with microwave radiometers. Atmospheric attenuation, observation gaps and errors in the microwave observations reduce the quality of daily radiometric observations. To deal with the attenuation due to vegetation and surface roughness, a two-step model was developed: the first step is to retrieve the polarization difference emissivity from Polarization Difference Brightness Temperature (PDBT) at 37 GHz with the simplified radiative transfer model and the vegetation optical thickness at 37 GHz parameterized from Normalized Difference Vegetation Index (NDVI) ; the second step is to retrieve the fractional area of WSS from the emissivity difference with a linear model, which can be parameterized according to the Qp surface roughness model. To remove the noise and extract the surface signal (including surface emittance and vegetation attenuation) from the daily PDBT time series, the Time Series Analysis Procedure (TSAP) was developed to identify the spectral features of noisy components in the frequency domain and remove them with a proper filter. The overall method combined the TSAP and the two-step model to derive daily observation of WSS area. The retrieved WSS area in the Poyang Lake floodplain was in a good agreement with the lake area observed from MODerate-resolution Imaging Spectroradiometer (MODIS) and Advanced Synthetic Aperture Radar (ASAR). The observations and analysis of the inundation patterns in the Poyang Lake and Dongting Lake floodplains with this method illustrated the close relationship between inundated area, precipitation and stream flow.
Furthermore, a lumped hydrological model, named the discrete rainfall-runoff model, was developed to fully use the retrieved WSS area and to study the role of inundated area in stream flow production. This model simulates stream flow as the integration of contributions of antecedent precipitation in a certain period. Three implementations of the model were developed with the help of ground water table depth and the retrieved WSS area. The case study in the Xiangjiang River basin (upstream catchment of the Dongting Lake floodplain), China, illustrated that: 1) the longest duration of antecedent precipitation is a key parameter to determine model performance; 2) long duration would increase the model uncertainty and lead to overfitting; 3) the application of the WSS area can reduce the duration required to achieve a reasonable accuracy. The model parameters indicated the interaction between stream flow and various water storages, and the calibration results of three implementations implied the recharge period of ground water.
w) by applying a new spectral indices-based unmixing algorithm to Medium Resolution Imaging Spectrometer Full Resolution (MERIS FR) data using a minimum number of spectral bands. These images are technically similar to the OLCI image data acquired by the Sentinel-3 satellite, which are to be systematically provided in the near future. The normalized difference wetness index (NDWI) was applied to delineate the water surface and combined with normalized difference vegetation index (NDVI) to account for emergent vegetation within the water bodies. The challenge to map flooded areas by applying spectral unmixing is the estimation of spectral endmembers, i.e., pure spectra of land cover features. In our study, we developed and applied a new unmixing method based on the use of an ensemble of spectral endmembers to capture and take into account spectral variability within each endmember. In our case study, forty realizations of the spectral endmembers gave a stable frequency distribution of γw. Quality of the flood map derived from the Envisat MERIS (MERIS) data was assessed against high (30 m) spatial resolution Landsat Thematic Mapper (TM) images on two different dates (17 April 2008 and 22 May 2009) during which floods occurred. The findings show that both the spatial and the frequency distribution of the γw extracted from the MERIS data were in good agreement with the high-resolution TM retrievals. The use of conventional linear unmixing, instead, applied using the entire available spectra for each image, resulted in relatively large differences between TM and MERIS retrievals.","Coarse resolution; Flood mapping; Fractional vegetation; Mixed pixel; NDWI; Remote sensing; Spectral unmixing","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:22328f6c-564d-4400-b18c-61472866c7ae","http://resolver.tudelft.nl/uuid:22328f6c-564d-4400-b18c-61472866c7ae","Generating high-temporal and spatial resolution tir image data","Herrero Huerta, M. (TU Delft Optical and Laser Remote Sensing); Lagüela, S. (Polytechnic School of Avila); Alfieri, S.M. (TU Delft Optical and Laser Remote Sensing); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences)","Lichti, D. (editor); Weng, Q (editor)","2017","Remote sensing imagery to monitor global biophysical dynamics requires the availability of thermal infrared data at high temporal and spatial resolution because of the rapid development of crops during the growing season and the fragmentation of most agricultural landscapes. Conversely, no single sensor meets these combined requirements. Data fusion approaches offer an alternative to exploit observations from multiple sensors, providing data sets with better properties. A novel spatio-temporal data fusion model based on constrained algorithms denoted as multisensor multiresolution technique (MMT) was developed and applied to generate TIR synthetic image data at both temporal and spatial high resolution. Firstly, an adaptive radiance model is applied based on spectral unmixing analysis of. TIR radiance data at TOA (top of atmosphere) collected by MODIS daily 1-km and Landsat - TIRS 16-day sampled at 30-m resolution are used to generate synthetic daily radiance images at TOA at 30-m spatial resolution. The next step consists of unmixing the 30 m (now lower resolution) images using the information about their pixel land-cover composition from co-registered images at higher spatial resolution. In our case study, TIR synthesized data were unmixed to the Sentinel 2 MSI with 10 m resolution. The constrained unmixing preserves all the available radiometric information of the 30 m images and involves the optimization of the number of landcover classes and the size of the moving window for spatial unmixing. Results are still being evaluated, with particular attention for the quality of the data streams required to apply our approach.","Data fusion; Image processing; Multisensor system; Remote sensing; Spectral unmixing; Thermal infrared data","en","conference paper","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:719daaa9-6c9e-4c44-9608-b58f3c614d94","http://resolver.tudelft.nl/uuid:719daaa9-6c9e-4c44-9608-b58f3c614d94","Marsh Recession and Erosion study of the Fraser Delta, B.C., Canada from Historic Satellite Imagery","Marijnissen, R.J.C. (TU Delft Coastal Engineering); Aarninkhof, S.G.J. (TU Delft Coastal Engineering)","","2017","class=""MsoNormal"">The goal of the study is to map the changes of marsh extent and topography on both Sturgeon Bank and Westham Island between 1980 and now. The study will look for a correlation between the recession and the possible loss of sediment from the banks. If a sediment deficit is a (major) contributor of marsh recession within the Fraser Delta, the results of the study should reveal such a connection.
Although there are plenty of studies suggesting changes have taken place in the marshes fronting the Fraser Delta, no study has utilized the extensive data record of satellites to study these changes for the entire Fraser Delta. Tools like the Aquamonitor can detect the changes in coastlines in the past 30 years from satellite imagery. More advanced tools are still in development like MI-SAFE, which detects inter-tidal elevations and vegetation on foreshores to estimate the potential risk reduction of flooding by coastal vegetation all across the world. Within the study the latest techniques from these tools are applied and adapted to the Fraser Delta. By using the full 30+ years of information on satellite imagery, the marsh and inter-tidal surface changes are examined from a new angle.","Remote sensing; satellite imaginary; marsh development; tidal flats; Frasier delta","en","report","Delft University of Technology","","","","","","","","","","Coastal Engineering","","",""
"uuid:0895480b-77c7-46a3-b013-f2ef0cb34019","http://resolver.tudelft.nl/uuid:0895480b-77c7-46a3-b013-f2ef0cb34019","Structural Health and Stability Assessment of High-Speed Railways via Thermal Dilation Mapping With Time-Series InSAR Analysis","Qin, Xiaoqiong (Wuhan University); Liao, Mingsheng (Wuhan University); Zhang, L (Wuhan University); Yang, M. (TU Delft Mathematical Geodesy and Positioning; Wuhan University)","","2017","Thermal dilation is a vital component of deformation along the extensive railway network infrastructure. To monitor subtle deformation, the synthetic aperture radar interferometry (InSAR) technique has been adopted as a space-borne geodetic tool. However, InSAR applications in railway stability surveillance have been largely limited by the sparseness of detectable point-like targets (PTs). Moreover, only one-dimensional linear displacements in radar line-of-sight direction can be measured by a single data stack. To address these issues, we developed an improved persistent scatterers InSAR approach that can retrieve thermal dilation effects with an increased number of PTs along the railways. This proposed strategy effectively combines SAR amplitude, interferometric phase, and the spatial information of railway structures to maximize the number of PTs. A least square fitting of the residual phase obtained by iterative spatial-temporal filtering with respect to temperature difference is used to estimate the thermal dilation of metal and concrete-asphalt materials. To validate the effectiveness of this approach, case studies using ENVISAT ASAR (ASAR) and TerraSAR-X (TSX) datasets were carried out on the railways of Beijing–Tianjin, Beijing–Shanghai, and Shanghai–Hangzhou. Subsidence velocity, gradient, and thermal dilation were used to identify hazardous grades along each railway. Furthermore, linear deformation rates in two dimensions, i.e., vertical and west-east directions, along Shanghai–Hangzhou Railway were inverted from ascending ASAR and descending TSX observations to reveal track conditions at a high level of detail.","Gradient; high-speed railway; Monitoring; Radar tracking; Rail transportation; Remote sensing; risk assessment; Stability analysis; Target tracking; thermal dilation; Thermal stability","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:493d723f-f445-426d-811b-a6428816c77a","http://resolver.tudelft.nl/uuid:493d723f-f445-426d-811b-a6428816c77a","Automatic detection of snow avalanche debris in central Svalbard using C-band SAR data","Wesselink, Dieuwertje S. (Northern Research Institute); Malnes, Eirik (Northern Research Institute); Eckerstorfer, Markus (Northern Research Institute); Lindenbergh, R.C. (TU Delft Optical and Laser Remote Sensing)","","2017","Snow avalanches pose a threat to people and infrastructure in and around Svalbard’s main settlement Longyearbyen. Since January 2016, publically available regional avalanche warnings are issued daily for Nordenskiöld Land, the area around Longyearbyen. Avalanche warning services rely on information of when and where avalanches occur. Systematic field observations of avalanche activity are not feasible across all of the vast area (ca. 7200 km2) of Nordenskiöld Land. Svalbard also experiences over four months of polar night per year. However, using synthetic aperture radar (SAR), a weather- and light-independent technique, large areas can be monitored at once. We have developed a SAR-based automatic avalanche debris detection algorithm and tested it on satellite image pairs from Sentinel-1A at medium resolution and from Radarsat-2 at very high resolution. The detection algorithm uses a threshold value that distinguishes avalanche debris with increased backscatter from undisturbed snow with lower backscatter. Depending on the spatial resolution of the SAR image, different post-processing filters are applied. There is a promising level of agreement between automatic detection results and manual identification of avalanche debris, but the algorithm’s drawback is marked overdetection. We envision that further improvements in the form of avalanche debris shape recognition could ultimately lead to the development of operational avalanche activity maps. These frequently updated maps could then assist in regional avalanche forecasting, notably in and around Longyearbyen, Svalbard. The detection algorithm we have developed could eventually have applications in other avalanche-prone regions in the world.","Avalanche debris detection; Avalanche forecasting; Radar remote sensing; Radarsat-2; Sentinel-1","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:af2cb450-216a-4cc1-bac0-88afa9dd1354","http://resolver.tudelft.nl/uuid:af2cb450-216a-4cc1-bac0-88afa9dd1354","Retrieving fall streaks within cloud systems using doppler radar","Pfitzenmaier, L. (TU Delft Atmospheric Remote Sensing); Dufournet, Y. (TU Delft Atmospheric Remote Sensing); Unal, C.M.H. (TU Delft Atmospheric Remote Sensing); Russchenberg, H.W.J. (TU Delft Geoscience and Remote Sensing)","","2017","The interaction of ice crystals with supercooled liquid droplets in mixed-phase clouds leads to an enhanced growth of ice particles. However, such processes are still not clearly understood although they are important processes for precipitation formation in midlatitudes. To better understand how ice particles grow within such clouds, changes in the microphysical parameters of a particle population falling through the cloud have to be analyzed. The Transportable Atmospheric Radar (TARA) can retrieve the full 3D Doppler velocity vector based on a unique three-beam configuration. Using the derived wind information, a new fall streak retrieval technique is proposed so that microphysical changes along those streaks can be studied. The method is based on Doppler measurements only. The shown examples measured during the Analysis of the Composition of Clouds with Extended Polarization Techniques (ACCEPT) campaign demonstrate that the retrieval is able to capture the fall streaks within different cloud systems. These fall streaks can be used to study changes in a single particle population from its generation (at cloud top) until its disintegration. In this study fall streaks are analyzed using radar moments or Doppler spectra. Synergetic measurements with other instruments during ACCEPT allow the detection of liquid layers within the clouds. The estimated microphysical information is used here to get a better understanding of the influence of supercooled liquid layers on ice crystal growth. This technique offers a new perspective for cloud microphysical studies.","Cloud microphysics; Ice crystals; Ice loss/growth; Radars/Radar observations; Remote sensing; Wind profilers; OA-Fund TU Delft","en","journal article","","","","","","","","","","Geoscience and Remote Sensing","Atmospheric Remote Sensing","","",""
"uuid:945e3eee-a6fe-4063-ac86-d0814eeb4301","http://resolver.tudelft.nl/uuid:945e3eee-a6fe-4063-ac86-d0814eeb4301","Evaluation criteria on the design for assimilating remote sensing data using variational approaches","Lu, S. (TU Delft Mathematical Physics); Heemink, A.W. (TU Delft Mathematical Physics); Lin, H.X. (TU Delft Mathematical Physics); Segers, Arjo (TNO); Fu, Guangliang (TU Delft Mathematical Physics)","","2017","Remote sensing, as a powerful tool for monitoring atmospheric phenomena, has been playing an increasingly important role in inverse modeling. Remote sensing instruments measure quantities that often combine several state variables as one. This creates very strong correlations between the state variables that share the same observation variable. This may cause numerical problems resulting in a low convergence rate or inaccurate estimates in gradient-based variational assimilation if improper error statistics are used. In this paper, two criteria or scoring rules are proposed to quantify the numerical robustness of assimilating a specific set of remote sensing observations and to quantify the reliability of the estimates of the parameters. The criteria are derived by analyzing how the correlations are created via shared observation data and how they may influence the process of variational data assimilation. Experimental tests are conducted and show a good level of agreement with theory. The results illustrate the capability of the criteria to indicate the reliability of the assimilation process. Both criteria can be used with observing system simulation experiments (OSSEs) and in combination with other verification scores.","Remote sensing; Inverse methods; Variational data assimilation; forecast evaluation; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Mathematical Physics","","",""
"uuid:81eb2519-1125-469b-b3f4-4674ea495f65","http://resolver.tudelft.nl/uuid:81eb2519-1125-469b-b3f4-4674ea495f65","Variational data assimilation of satellite observations to estimate volcanic ash emissions","Lu, S. (TU Delft Mathematical Physics)","Lin, H.X. (promotor); Heemink, A.W. (promotor); Delft University of Technology (degree granting institution)","2017","Volcanic eruptions release a large amount of volcanic ash, which can pose hazard to human and animal health, land transportation, and aviation safety. Volcanic Ash Transport and Dispersion (VATD) models are critical tools to provide advisory information and timely volcanic ash forecasts. Due to the complexity and the uncertainty of many dynamic processes involved in the volcanic ash distribution, even the most advanced VATDs today are not capable to reproduce the reality accurately. It is necessary to integrate available observations in the models for more accurate predictions by employing data assimilation techniques.In addition to a valid VATD, ash emissions, usually used as input so the model, are crucial for the forecasts of the locations and shapes of the ash cloud. In general, the eruption source parameters for the construction of the emission are poorly known, which include Plume Height (PH), Mass Eruption Rate (MER) and vertical distribution of the emission rate. Even when PH can be obtained from ground-based observations in some cases, the emission source computed from this PH and a MER empirically related to this PH remains highly uncertain. Not to mention the volcanoes which are unmonitored or hardly accessible, the PH can merely be retrieved from satellite data with a large uncertainty and temporal insufficiency. Fortunately, satellite instruments are able to observe the movement of an ash cloud with a global coverage. Therefore, this thesis focuses on the estimation of the volcanic ash emissions by assimilating Ash Mass Loadings (AMLs) retrieved from satellite data to improve the accuracy of forecasts. Among all available data assimilation approaches, Four Dimensional Variational assimilation (4D-Var) approach was chosen as a suitable one. 4D-Var seeks an optimal set of parameters, including model states, initial conditions and systematic parameters, by minimizing a cost function which combines the model simulations and observations over a period according to their statistic properties. 4D-Var with a standard form of the cost function is tested in a twin experiment framework, where synthetic observations of ash columns computed from model simulated 3D ash concentrations are used. The results show that Standard 4DVar (Std4DVar) is unable to reconstruct the vertical profile of the emission. The injection layer containing the maximal amount of emission rate cannot be accurately determined. This failure is attributed to the fact that AML data lacks vertical resolution. Using the AMLs, it is difficult to reconstruct the volcanic ash emission presented in forms of an eruption column.To deal with this problem, a Trajectory-based 4D-Var (Trj4DVar) approach is proposed. Trj4DVar reformulates the cost function in a regression type which computes the total difference between observed ash columns and a linear combination of simulated trajectories coupled with a priori emission knowledge. The results of twin experiments show that, for most cases, Trj4DVar is capable of estimating the input emission column when a large assimilation window (> 6 hours) is used. The twin experiments is repeated where different values of noise are given in the synthetic observations or perturbations are used in the meteorologic data. The outcomes show that there is still a small possibility that Trj4DVar fails to determine the injection height accurately. Being disturbed by the weather condition (light and cloud, etc) at that moment, satellite instrument can be hampered to observe the ash cloud, which may increase the possibility of failure for the use of Trj4DVar. To remedy this, Trj4DVar is modified to incorporate observations of PH and MER in addition to satellite AMLs. The modified Trj4DVar is shown to be able accurately estimate the injection height based on the results of twin experiments.When it comes to using real-life field data, the situation is more complicated. The detection of volcanic ash can be disturbed by the weather condition such as water vapor. This will result in observations of undetected or wrongly-detected ash. Besides, many sensors ,such as UV and visible sensors, have limited temporal coverage which can only observe during daylight. In order to find effective method in dealing with the temporal and sometimes spatial insufficiency of the data, investigations are carried out on how to use the data properly to benefit more and produce a reasonable estimate. A prepossessing procedure and guidance on the proper use of satellite data are presented.Finally, a deeper analysis is given on the failure of using Std4DVar in this application. It is found that using Std4DVar to assimilate remote sensing data can be tricky. Remote sensing measures quantities that combine several state variables. This creates Sensor-Induced Correlations between the state variables which share the same observation variable and may be physically unrelated. This may cause numerical problems resulting in a low convergence rate or inaccurate estimates of parameters using gradient-based variational assimilation if an erroneous or improper specification of error statistics is adopted. These problems are usually ignored when a reasonable result is obtained, or are avoided by reducing the 3D model to a 2D model. However, it results in significantly unreliable and misguiding estimates for the application in this thesis. Two criteria are proposed to quantify the negative effects of the SICs, which give indications of the effectiveness of the assimilation process and the forecast quality. They are simple to implement and very practical for the use of remote sensing data. They are tested in the twin experiments. The results show that they are able to give evaluation on the design and configuration of the assimilation system with remote sensing data.","Variational data assimilation; Data assimilation; 4D-Var; Correlations; Trajectory-based 4D-Var; Volcanic ash emissions; Volcanic ash forecast; Volcanic ash; Remote sensing measurements; Evaluation score","en","doctoral thesis","","978-94-92516-43-5","","","","","","","","","Mathematical Physics","","",""
"uuid:3161decf-e217-4dc2-a526-ab87beb17ce8","http://resolver.tudelft.nl/uuid:3161decf-e217-4dc2-a526-ab87beb17ce8","A simple global Budyko model to partition evaporation into interception and transpiration","Mianabadi, A. (Ferdowsi University of Mashhad); Coenders-Gerrits, Miriam (TU Delft Water Resources); Shirazi, P. (Ferdowsi University of Mashhad); Ghahraman, B. (Ferdowsi University of Mashhad); Alizadeh, Amin (Ferdowsi University of Mashhad)","","2017","Evaporation is a very important flux in the hydrological cycle and links the water and energy balance of a catchment. The Budyko framework is often used to provide a first order estimate of evaporation, since it is a simple model where only rainfall and potential evaporation is required as input. Many researchers have tried to improve the Budyko framework by including more physics and catchment characteristics into the original equation. However, this often resulted in additional parameters, which are unknown or difficult to determine. In this paper we present an improvement of the previously presented Gerrits' model (“Analytical derivation of the Budyko curve based on rainfall characteristics and a simple evaporation model” in Gerrits et al., 2009 WRR), whereby total evaporation is calculated on the basis of simple interception and transpiration thresholds in combination with measurable parameters like rainfall dynamics and storage availability from remotely sensed data sources. While Gerrits' model was investigated for 10 catchments with different climate conditions and also some parameters were assumed to be constant, in this study we applied the model on the global scale and it was fed with remotely sensed input data. The output of the model is compared to two complex land–surface models STEAM and GLEAM, as well as the database of Landflux-EVAL. Our results showed that total evaporation estimated by Gerrits' model is in good agreement with Landflux-EVAL, STEAM and GLEAM. Results also show that Gerrits’ model underestimated interception in comparison to STEAM and overestimated in comparison to GLEAM, while for transpiration the opposite was found. Errors in interception can partly be explained by differences in the interception definition that successively introduce errors in the calculation of transpiration. Comparing to the Budyko framework, the model showed a good performance for total evaporation estimation and the results are closer to Ol'dekop than Schreiber, Pike and Budyko curves.","Budyko curves; interception; transpiration; remote sensing; evaporation","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:99ac6ef8-6ed4-4dbd-b38a-8ef11a569081","http://resolver.tudelft.nl/uuid:99ac6ef8-6ed4-4dbd-b38a-8ef11a569081","Evaluation of methods for aerodynamic roughness length retrieval from very high-resolution imaging LIDAR observations over the heihe basin in China","Faivre, R.D. (University of Strasbourg); Colin, Jérôme (University of Strasbourg); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences)","","2017","The parameterization of heat transfer based on remote sensing data, and the Surface Energy Balance System (SEBS) scheme to retrieve turbulent heat fluxes, already proved to be very appropriate for estimating evapotranspiration (ET) over homogeneous land surfaces. However, the use of such a method over heterogeneous landscapes (e.g., semi-arid regions or agricultural land) becomes more difficult, since the principle of similarity theory is compromised by the presence of different heat sources at various heights. This study aims to propose and evaluate some models based on vegetation geometry partly developed by Colin and Faivre, to retrieve the surface aerodynamic roughness length for momentum transfer (z0m), which is a key parameter in the characterization of heat transfer. A new approach proposed by the authors consisted in the use of a Digital Surface Model (DSM) as boundary condition for experiments with a Computational Fluid Dynamics (CFD) model to reproduce 3D wind fields, and to invert them to retrieve a spatialized roughness parameter. Colin and Faivre also applied the geometrical Raupach's approach for the same purpose. These two methods were evaluated against two empirical ones, widely used in Surface Energy Balance Index (SEBI) based algorithms (Moran; Brutsaert), and also against an alternate geometrical model proposed by Menenti and Ritchie. The investigation was carried out in the Yingke oasis (China) using very-high resolution remote sensing data (VNIR, TIR & LIDAR), for a precise description of the land surface, and a fine evaluation of estimated heat fluxes based on in-situ measurements. A set of five numerical experiments was carried out to evaluate each roughness model. It appears that methods used in experiments 2 (based on Brutsaert) and 4 (based on Colin and Faivre) are the most accurate to estimate the aerodynamic roughness length, according to the estimated heat fluxes. However, the formulation used in experiment 2 allows to minimize errors in both latent and sensible heat flux, and to preserve a good partitioning. An additional evaluation of these two methods based on another kB-1 parameterization could be necessary, given that the latter is not always compatible with the CFD-based retrieval method.","Evapotranspiration; Heat transfer; Heterogeneous land surfaces; Light detection and ranging (LIDAR); Optical remote sensing; Roughness length; Surface energy balance","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:1cbd8845-dd4c-40a7-b893-72c4e0a6f21f","http://resolver.tudelft.nl/uuid:1cbd8845-dd4c-40a7-b893-72c4e0a6f21f","Regional surface soil heat flux estimate from multiple remote sensing data in a temperate and semiarid basin","Li, Nana (Chinese Academy of Sciences; Tsinghua University; Joint Center for Global Change Studies); Jia, Li (Chinese Academy of Sciences; Joint Center for Global Change Studies); Lu, Jing (Chinese Academy of Sciences; Joint Center for Global Change Studies); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Zhou, J. (TU Delft Optical and Laser Remote Sensing)","","2017","The regional surface soil heat flux (G0) estimation is very important for the large-scale land surface process modeling. However, most of the regional G0 estimation methods are based on the empirical relationship between G0 and the net radiation flux. A physical model based on harmonic analysis was improved (referred to as ""HM model"") and applied over the Heihe River Basin northwest China with multiple remote sensing data, e.g., FY-2C, AMSR-E, and MODIS, and soil map data. The sensitivity analysis of the model was studied as well. The results show that the improved model describes the variation of G0 well. Land surface temperature (LST) and thermal inertia (Γ) are the two key input variables to the HM model. Compared with in situ G0, there are some differences, mainly due to the differences between remote-sensed LST and the in situ LST. The sensitivity analysis shows that the errors from-7 to-0.5K in LST amplitude and from-300 to 300J m-2 K-1 s-0.5 in Γ will cause about 20% errors, which are acceptable for G0 estimation.","arid and semiarid area; Harmonic analysis model; regional soil heat flux; remote sensing data; thermal inertia","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:29afd98d-4ff4-497f-8e22-e6b2b9d7fd6d","http://resolver.tudelft.nl/uuid:29afd98d-4ff4-497f-8e22-e6b2b9d7fd6d","Using satellite imagery analysis to classify and redesign provincial parks for a better cooling effect on cities: The case study of South Holland","Echevarria Icaza, L. (TU Delft OLD Urban Compositions); van den Dobbelsteen, A.A.J.F. (TU Delft Architectural Engineering +Technology); van der Hoeven, F.D. (TU Delft OLD Urban Design; TU Delft 100% Research)","","2016","The purpose of this research is to analyse the thermal behaviour of South Holland provincial parks during heat waves, in order to provide design adaptation guidelines to increase their cooling capacity over the hotspots present in their urban surroundings. This research analyses the thermal behaviour of different land use patches (forests, cropland, grassland, water surfaces, built areas and greenhouse areas) present in the six South Holland provincial parks during heat waves. It studies their average night land surface temperature (LST) (with Modis 11A1), day LST (with Landsat 5TM), NDVI, imperviousness, patch size and patch shape index, and analyses through a multiple regression analysis the impact of each of these last four parameters in the night and day LST for each land use. Within each land use category, NDVI, imperviousness and patch shape index influence differently the thermal behaviour of the patches. NDVI is inversely correlated to day LST for all categories, imperviousness is correlated to day LST for all areas which do not comprise a significant presence of greenhouses (grassland and built patches) and inversely correlated to LST for areas with a high presence of greenhouses (cropland and warehouses). Finally the shape index varies depending on the nature of the surrounding patches, especially for small patches (built areas, forests and greenhouse areas). Most of the hotspots surrounding the Midden-Delfland park are adjacent to grassland patches. The measure to increase the cooling capacity of those patches would consist in a change of land use and or an increase of the NDVI of the existing grassland patches. These suggestions to increase the cooling potential of the parks remain deliberately open in order to allow combining these measures with other spatial planning priorities.","urbanism; remote sensing; GIS; urban heat island; cooling effect; climate change adaptation; landscape design","en","journal article","","","","","","","","","","Architectural Engineering +Technology","OLD Urban Compositions","","",""
"uuid:156da0d0-086a-4a5c-b944-c7fe921e11c7","http://resolver.tudelft.nl/uuid:156da0d0-086a-4a5c-b944-c7fe921e11c7","Managing Basin Interdependencies in a Heterogeneous, Highly Utilized and Data Scarce River Basin in Semi-Arid Africa: The case of the Pangani River Basin, Eastern Africa","Kiptala, J.K. (TU Delft Water Resources)","van der Zaag, P. (promotor); Mohamed, YA (copromotor); Delft University of Technology (degree granting institution)","2016","For integrated water resources management both blue and green water resources in a river basin and their spatial and temporal distribution have to be considered. This is because green and blue water uses are interdependent. In sub-Saharan Africa, the upper landscapes are often dominated by rainfed and supplementary irrigated agriculture that rely on green water resources. Downstream, most blue water uses are confined to the river channels, mainly for hydropower and the environment. Over time and due to population growth and increased demands for food and energy, water use of both green and blue water has increased. This book provides a quantitative assessment of green-blue water use and their interactions. The book makes a novel contribution by developing a hydrological model that can quantify not only green but also blue water use by many smallholder farmers scattered throughout the landscape. The book provides an innovative framework for mapping ecological productivity where gross returns from water consumed in agricultural and natural vegetation are quantified. The book provides a multi-objective optimization analysis involving green and blue water users, including the environment. The book also assesses the uncertainty levels of using remote sensing data in water resource management at river basin scale.","Land use and land cover; Evapotranspiration; Biomass; MODIS; Remote sensing; Reservoir operation; SEBAL; Water productivity; Water value; Water allocation; Soil water; Green water; Rainfed agriculture; Supplementary irrigation; Kilimanjaro; Arusha","en","doctoral thesis","CRC Press / Balkema - Taylor & Francis Group","978-1-138-03609-3","","","","Dissertation submitted in fulfilment of the requirements of the Board for Doctorates of Delft University of Technology and of the Academic Board of the UNESCO-IHE Institute for Water Education.","","","","","Water Resources","","",""
"uuid:338218a9-94ec-49f9-a64d-61ffc10a7b3f","http://resolver.tudelft.nl/uuid:338218a9-94ec-49f9-a64d-61ffc10a7b3f","Surface thermal analysis of North Brabant cities and neighbourhoods during heat waves","Echevarria Icaza, L. (TU Delft OLD Urban Compositions); van der Hoeven, F.D. (TU Delft OLD Urban Design; TU Delft 100% Research); van den Dobbelsteen, A.A.J.F. (TU Delft Architectural Engineering +Technology)","","2016","The urban heat island effect is often associated with large metropolises. However, in the Netherlands even small cities will be affected by the phenomenon in the future (Hove et al., 2011), due to the dispersed or mosaic urbanisation patterns in particularly the southern part of the country: the province of North Brabant. This study analyses the average night time land surface temperature (LST) of 21 North-Brabant urban areas through 22 satellite images retrieved by Modis 11A1 during the 2006 heat wave and uses Landsat 5 Thematic Mapper to map albedo and normalized difference temperature index (NDVI) values. Albedo, NDVI and imperviousness are found to play the most relevant role in the increase of nighttime LST. The surface cover cluster analysis of these three parameters reveals that the 12 “urban living environment” categories used in the region of North Brabant can actually be reduced to 7 categories, which simplifies the design guidelines to improve the surface
thermal behaviour of the different neighbourhoods thus reducing the Urban Heat Island (UHI) effect in existing medium size cities and future developments
adjacent to those cities.","urban heat island; climate change; sustainable urban planning; remote sensing","en","journal article","","","","","","","","","","Architectural Engineering +Technology","OLD Urban Compositions","","",""
"uuid:0a2324a2-675b-4fb5-8292-288969a35875","http://resolver.tudelft.nl/uuid:0a2324a2-675b-4fb5-8292-288969a35875","Towards Urban Facilities Energy Performance Evaluation Using Remote Sensing","Jazizadeh, F. (Virginia Tech); Taleghani, M. (TU Delft Climate Design and Sustainability; University of Southern California)","","2016","Urban facilities are major contributors to annual energy consumption and therefore, evaluating their energy efficiency and retrofit planning play a major role in achieving sustainability goals. For urban facilities, such as buildings, energy performance audits could be conducted by detailed evaluation at building level. However, at urban level, detailed evaluation is cost and time intensive. Therefore, in this study, we investigated the correlation between land surface temperature, obtained through satellite imagery, and energy consumption patterns at urban level to explore its feasibility for energy performance evaluations. New York City was used as the main case study for conducting the analysis. We have investigated the correlation between energy consumption intensity and temperature at city block level for selected points. The outcome demonstrates a strong correlation between energy consumption intensity and land surface temperature. The observed correlation could potentially be leveraged for developing an approach for energy performance auditing.","Energy management; Remote sensing; Thermal imagery; Urban facilities","en","journal article","","","","","","","","","","","Climate Design and Sustainability","","",""
"uuid:e4c70e88-d5cb-406e-a1b5-69b68486e3d3","http://resolver.tudelft.nl/uuid:e4c70e88-d5cb-406e-a1b5-69b68486e3d3","A space weather information service based upon remote and in-situ measurements of coronal mass ejections heading for earth","Ritter, B.; Meskers, A.J.H.; Miles, O.; Russwurm, M.; Scully, S.; Roldan, A.; Hartkorn, O.; Jüstel, P.; Réville, V.; Lupu, S.; Ruffenach, A.","","2015","The Earth’s magnetosphere is formed as a consequence of interaction between the planet’s magnetic field and the solar wind, a continuous plasma stream from the Sun. A number of different solar wind phenomena have been studied over the past 40 years with the intention of understanding and forecasting solar behavior. One of these phenomena in particular, Earth-bound interplanetary coronal mass ejections (CMEs), can significantly disturb the Earth’s magnetosphere for a short time and cause geomagnetic storms. This publication presents a mission concept consisting of six spacecraft that are equally spaced in a heliocentric orbit at 0.72 AU. These spacecraft will monitor the plasma properties, the magnetic field’s orientation and magnitude, and the 3D-propagation trajectory of CMEs heading for Earth. The primary objective of this mission is to increase space weather forecasting time by means of a near real-time information service, that is based upon in-situ and remote measurements of the aforementioned CME properties. The obtained data can additionally be used for updating scientific models. This update is the mission’s secondary objective. In-situ measurements are performed using a Solar Wind Analyzer instrumentation package and fluxgate magnetometers, while for remote measurements coronagraphs are employed. The proposed instruments originate from other space missions with the intention to reduce mission costs and to streamline the mission design process. Communication with the six identical spacecraft is realized via a deep space network consisting of six ground stations. They provide an information service that is in uninterrupted contact with the spacecraft, allowing for continuous space weather monitoring. A dedicated data processing center will handle all the data, and then forward the processed data to the SSA Space Weather Coordination Center which will, in turn, inform the general public through a space weather forecast. The data processing center will additionally archive the data for the scientific community. The proposed concept mission allows for major advances in space weather forecasting time and the scientific modeling of space weather.","Coronal Mass Ejection (CME); remote sensing; in-situ measurement; geomagnetic storms; forecast; services","en","journal article","EDP Sciences","","","","","","","","Mechanical, Maritime and Materials Engineering","Precision and Microsystems Engineering","","","",""
"uuid:2da9ba68-723c-4741-bdea-8208445e24be","http://resolver.tudelft.nl/uuid:2da9ba68-723c-4741-bdea-8208445e24be","Simulation of Groundwater-Surface Water Interactions under Different Land Use Scenarios in the Bulang Catchment, Northwest China","Yang, Z.; Zhou, Y.; Wenninger, J.; Uhlenbrook, S.; Wan, L.","","2015","Groundwater is the most important resource for local society and the ecosystem in the semi-arid Hailiutu River catchment. The catchment water balance was analyzed by considering vegetation types with the Normalized Difference Vegetation Index (NDVI), determining evapotranspiration rates by combining sap flow measurements and NDVI values, recorded precipitation, measured river discharge and groundwater levels from November 2010 to October 2011. A simple water balance computation, a steady state groundwater flow model, and a transient groundwater flow model were used to assess water balance changes under different land use scenarios. It was shown that 91% of the precipitation is consumed by the crops, bushes and trees; only 9% of the annual precipitation becomes net groundwater recharge which maintains a stable stream discharge in observed year. Four land use scenarios were formulated for assessing the impacts of land use changes on the catchment water balance, the river discharge, and groundwater storage in the Bulang catchment. The scenarios are: (1) the quasi natural state of the vegetation covered by desert grasses; (2) the current land use/vegetation types; (3) the change of crop types to dry resistant crops; and (4) the ideal land use covered by dry resistant crops and desert grasses, These four scenarios were simulated and compared with measured data from 2011, which was a dry year. Furthermore, the scenarios (2) and (4) were evaluated under normal and wet conditions for years in 2009 and 2014, respectively. The simulation results show that replacing current vegetation and crop types with dry resistant types can significantly increase net groundwater recharge which leads to the increase of groundwater storage and river discharges. The depleted groundwater storage during the dry year could be restored during the normal and wet years so that groundwater provides a reliable resource to sustain river discharge and the dependent vegetations in the area.","groundwater-surface water interactions; remote sensing; land use scenarios; simulation model; catchment water balance","en","journal article","MDPI","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:031dab85-cd80-462d-9b7c-4a5da79a8c64","http://resolver.tudelft.nl/uuid:031dab85-cd80-462d-9b7c-4a5da79a8c64","Ecosystem service monitoring using remote sensing, citizen science and other ground observations and current practices in Vietnam","Pham, N.Q.; Tran, H.N.; Thi, K.V.L.; Nong, A.B.; Rutten, M.M.","","2015","Ecosystems are providing a stream of essential goods and services for the national socio-economic prosperity and welfare; paradoxically, these services have to suffer a high vulnerability against the increasingly uncontrolled use of human beings. World-wide researchers and authorities are working to ensure the sustainability of nature; and scientifically, any methodology aiming to maintain the good services of ecosystem is normally kicked off by analyzing data; regarding this point of view, monitoring data has emphasized its crucial role, especially for natural resources management and planning at both global and local scale. Realistically, monitoring data can facilitate the policy making process and management of natural resources that are rising intricately under high pressure of human interventions. Vietnam Government gives a high priority in developing the national environment monitoring network; recently, improvement of techniques has changed the approach of water monitoring in the country. In addition to the presenting an overview of ground observation methods conventionally used in Vietnam, this study presents the potential of other monitoring techniques such as remote sensing, sensors, citizen science and their linkage. Finally, an analysis specifying the gap of applications in Vietnam and other parts of the world is provided.","monitoring; remote sensing; citizen science; sustainable; ecosystem services","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:4cc4050e-55dd-4687-9873-3b3ad727ebb0","http://resolver.tudelft.nl/uuid:4cc4050e-55dd-4687-9873-3b3ad727ebb0","Predicting the ungauged basin: Model validation and realism assessment","Van Emmerik, T.H.M.; Mulder, G.; Eilander, D.; Piet, M.; Savenije, H.H.G.","","2015","The hydrological decade on Predictions in Ungauged Basins (PUB) led to many new insights in model development, calibration strategies, data acquisition and uncertainty analysis. Due to a limited amount of published studies on genuinely ungauged basins, model validation and realism assessment of model outcome has not been discussed to a great extent. With this paper we aim to contribute to the discussion on how one can determine the value and validity of a hydrological model developed for an ungauged basin. As in many cases no local, or even regional, data are available, alternative methods should be applied. Using a PUB case study in a genuinely ungauged basin in southern Cambodia, we give several examples of how one can use different types of soft data to improve model design, calibrate and validate the model, and assess the realism of the model output. A rainfall-runoff model was coupled to an irrigation reservoir, allowing the use of additional and unconventional data. The model was mainly forced with remote sensing data, and local knowledge was used to constrain the parameters. Model realism assessment was done using data from surveys. This resulted in a successful reconstruction of the reservoir dynamics, and revealed the different hydrological characteristics of the two topographical classes. This paper does not present a generic approach that can be transferred to other ungauged catchments, but it aims to show how clever model design and alternative data acquisition can result in a valuable hydrological model for an ungauged catchment.","PUB; hydrologic modeling; Cambodia; ungauged basins; remote sensing; model realism; model validation; soft data","en","journal article","Frontiers","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:0ec9edf7-5eac-4191-b63d-9a6c7e3619af","http://resolver.tudelft.nl/uuid:0ec9edf7-5eac-4191-b63d-9a6c7e3619af","Evolution of wind towards wind turbine","Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2015","Remote sensing of the atmospheric variables with the use of LiDAR is a relatively new technology field for wind resource assessment in wind energy. The validation of LiDAR measurements and comparisons is of high importance for further applications of the data.","wind evolution; remote sensing; lidar data; wind field modelling","en","conference paper","EAWE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5bbbca9b-7bb4-4808-bed5-caf23d7b0f62","http://resolver.tudelft.nl/uuid:5bbbca9b-7bb4-4808-bed5-caf23d7b0f62","Analyzing the inundation pattern of the Poyang Lake floodplain by passive microwave data","Shang, H.; Li, J.; Menenti, M.","","2015","The soil wetness condition is a useful indicator of inundation hazard in floodplains, such as the Poyang Lake floodplain. Special Sensor Microwave Imager (SSM/I) passive microwave data were used to monitor water-saturated soil and open water areas of the Poyang Lake floodplain from 2001 to 2008, capturing the inundation patterns of this area in space and time. The polarization difference brightness temperature (PDBT) at 37 GHz is sensitive to the water extension even under dense vegetation. The zero-order radiative transfer model was simplified to retrieve the vertical–horizontal (V–H)-polarized effective emissivity difference from the PDBT at 37 GHz. Vegetation fractional area and vegetation transmission function were derived from NDVI to represent the vegetation attenuation. This effective emissivity difference has a quasi-linear relationship with the fractional area of water-saturated soil and standing water, no matter the frequency. Using the multifrequency-polarization surface emission (Qp) model and the Dobson model of the soil–water mixture, the two segments of this relationship were combined into a quasi-linear model. Comparing the retrieved water-saturated soil and standing water area of Poyang Lake with the lake area obtained from the MODIS and synthetic aperture radar (SAR) image at higher spatial resolution, the calculations show a good fit with the MODIS and SAR data, with R2 = 0.7664 and relative RMSE = 17.74%. The cross-correlation analysis shows that the Poyang Lake extension fluctuates with a 5-day time lag with the upstream land area of water-saturated soil and standing water. Since the closure of the Three Gorges Dam, this relationship is more evident.","streamflow; microwave observations; remote sensing; Fourier analysis; time series; lake effects","en","journal article","American Meteorological Society","","","","","","","2015-10-08","Civil Engineering and Geosciences","Geoscience and Remote Sensing","","","",""
"uuid:9c7d192f-ddda-482c-88d0-29eb38e2ae39","http://resolver.tudelft.nl/uuid:9c7d192f-ddda-482c-88d0-29eb38e2ae39","Estimation of Aerodynamic Roughness Length over Oasis in the Heihe River Basin by Utilizing Remote Sensing and Ground Data","Chen, Q.; Jia, L.; Hutjes, R.; Menenti, M.","","2015","Most land surface models require information on aerodynamic roughness length and its temporal and spatial variability. This research presents a practical approach for determining the aerodynamic roughness length at fine temporal and spatial resolution over the landscape by combining remote sensing and ground measurements. The basic framework of Raupach, with the bulk surface parameters redefined by Jasinski et al., has been applied to optical remote sensing data collected by the HJ-1A/1B satellites. In addition, a method for estimating vegetation height was introduced to derive the aerodynamic roughness length, which is preferred by users over the height-normalized form. Finally, mapping different vegetation classes was validated taking advantage of the data-dense field experiments conducted in the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) project. Overall, the roughness model performed well against the measurements collected at most HiWATER flux tower sites. However, deviations still occurred at some sites, which have been further analyzed.","aerodynamic roughness length; remote sensing; regional scale; agricultural; Heihe","en","journal article","MDPI","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:89e13a16-b456-4692-92f0-7a40ada82451","http://resolver.tudelft.nl/uuid:89e13a16-b456-4692-92f0-7a40ada82451","Moisture in the topsoil: From large-scale observations to small-scale process understanding","Rutten, M.M.","Van de Giesen, N.C. (promotor)","2015","The boundary that separates the earth from the atmosphere is a crucial zone of study for meteorology and hydrology. Here, solar energy is partitioned into sensible heat which drives atmospheric circulation, latent heat needed for evaporation from the soil and transpiration of vegetation, and soil heat which warms the subsurface. Precipitation is partitioned into interception that evaporates directly into the atmosphere, surface runoff that discharges quickly into water courses and infiltration which resides longer in the subsurface. Soil moisture influences all these processes and is therefore considered a key variable in land-atmosphere interaction. In order to obtain a better understanding of the heat and water balance of topsoil, observations are key, but challenging with in situ point sensors. Recent rapid developments in remote sensing have tremendously increased our ability to observe the boundary between soil and atmosphere. Retrieving state variables such as soil temperature and moisture from remote sensing is far from trivial: detected signals originate not only from the soil, but also from the atmosphere and vegetation, the depth of the detection is a function of the soil moisture itself, and pixels are large and heterogeneous. Field validation is difficult, because of scale disparity between in situ point sensors and remote sensing pixels. Still, given the limitations, remote sensing provides an opportunity to improve understanding of heat and moisture transfer in the topsoil. The central question of this research is: What can be learnt from (remote sensing) observations about the heat and moisture balance of the topsoil? First a cross validation of different soil moisture products based on remote sensing was performed to investigate similarities and differences between these products. The differences were significant and could be attributed to differences in land use and vegetation, but not fully explained. This illustrated that retrieval algorithms for soil moisture are far from converged. One prerequisite for improving retrieval algorithms is ground truth, ground observations at scales relevant for remote sensing. Second, a field technique was developed that can potentially be used for bridging the observation gap between point sensors and remote sensing pixels. This technique uses Distributed Temperature Sensing (DTS) over horizontal extents up to kilometers to infer soil moisture at this intermediate scale. Propagation of variations in atmospheric temperature and radiation with depth is a function of soil moisture. By using DTS observations at three depths, it is possible to infer soil moisture, assuming that heat conduction is the dominant heat transfer mechanism. The heat diffusion equation is inverted to obtain estimates of soil heat diffusivity and soil moisture. Since this technique relies on observations of the passive thermal response of the soil to atmospheric temperature and radiation variations, this technique is called passive SoilDTS in contrast to active soil DTS, which relies on active heat pulses. The feasibility of passive SoilDTS for soil moisture estimation was asserted in a field experiment conducted in Monster in the Netherlands. The analysis of the experimental results of this feasibility study pointed out a number of technical and modeling issues that needed to be investigated further in order for passive SoilDTS to be used for soil moisture estimation and scaling. Some soil moisture estimates were not reasonable due to uncertainties in cable depths and heat transfer mechanisms. To separate the technical issue of cable depth from the modeling challenges, the same methodology used to infer soil moisture from passive SoilDTS was applied to profile data of temperature and soil moisture obtained with point sensors. The depth of these point sensors could be determined with far greater accuracy than the cable depth. Analysis of the point observations challenged the common assumption that conduction is the dominant heat transfer mechanism in soil. Evaporation seemed to play a dominant role in heat transfer on dry days. Yet evaporation rates found were higher than would be expected if mass diffusion would be the dominant transfer mechanism of water vapor. Vapor diffusion appeared to be enhanced. Enhancement of vapor diffusion is a long-studied phenomenon, subject to debate on the explanations of underlying mechanism. In an extensive literature review on vapor enhancement in soils, the plausibility of various mechanisms was assessed. We reviewed mechanisms based on (combinations of) diffusive, viscous, buoyant, capillary and external pressure forces including: thermodiffusion, dispersion, Stefan’s flow, Knudsen diffusion, liquid island effect, hydraulic lift, free convection, double diffusive convection and forced convection. The analysis of the order of magnitude of the mechanisms based on first principles clearly distinguishes between plausible and implausible mechanisms. Thermodiffusion, Stefan’s flow, Knudsen effects, liquid islands do not significantly contribute to enhanced evaporation. Double diffusive convection seemed unlikely due to lack of experimental evidence, but could not be completely excluded from the list of potential mechanisms. Hydraulic lift, the mechanism that small capillaries lift liquid water to the surface where it evaporates, does significantly contribute to enhanced evaporation from soils, also from dryer soils. The experimental evidence for and the theoretical underpinnings of this mechanism are convincing. However, we sought mechanisms that both explain enhanced evaporation and steep temperature gradients in the soil during the daytime. These often observed gradients consist of a sharp decrease of temperature with a depth up to the depth of the evaporation front. Hydraulic lift cannot explain this because the evaporation front is located at the surface. One remaining mechanism is forced convection due to atmospheric pressure fluctuations, also referred to as wind pumping. Wind pumping causes displacement and flow velocities too small for significant convective and too small for significant dispersive transport, when steady state dispersion formulations are used. However, experiments do indicate significant dispersive transport that can be explained by dispersion under unsteady flow conditions. Forced convection due to pressure fluctuations seems to be the only mechanism that can explain both enhanced evaporation and the steep temperature gradients. We investigated under which conditions wind pumping can enhance water vapor transfer from the soil to the atmosphere and which mechanisms are responsible for this enhancement in a modeling study. Previous models of wind pumping relied on enhanced transfer due to enhanced mixing described with empirical macroscopic dispersion coefficients with weak physical foundations. We searched for better understanding of physical mechanisms driving enhanced mixing. With combination of order of magnitude analysis, phenomenological, empirical and analytical models, mechanisms were investigated. A model for surface pressure fluctuations was coupled with a pressure diffusion model, a pore flow velocity model and a dispersion model. Based on this coupled model, we propose that the enhancement is caused by mixing at the pore level due to flow instabilities. Fast pressure fluctuations at the soil-air interface make vortices in the soil unstable. Instabilities arise when the timescale of the pressure fluctuations is close to the timescale of viscous dissipation which is related to the pore size. In this case, vortices in the soil cannot increase, decrease and turn direction, in phase with the pressure fluctuations and instabilities occur in the form of ejections. The ejections of vortices enhance mixing and transport. Timescales of wind induced pressure fluctuations and pore sizes are such that this mechanism is considered likely in soils. Further research is needed to prove this mechanism and quantify it. The developed model is a hypothesis and should be tested with numerical and laboratory experiments. For estimating the effect of this vapor enhancement on the soil heat budget, a coupled heat and moisture transfer model should be developed. Such a model could also shed light on the relative importance of hydraulic lift and wind pumping for evaporation rates. Perhaps, because the topsoil forms the boundary between land and atmosphere, but also between two disciplines meteorology and hydrology, there are still many questions that remain about heat and moisture transfer in the upper few centimeters of the soil. Remote sensing soil moisture retrievals force the scientific community to revisit our understanding of the topsoil. As a result, remote sensing presents not only a challenge for ground validation, but also an opportunity for hydrological and meteorological model improvement. Observation is the beginning of most learning.","soil moisture; soil temperature; remote sensing; land atmosphere interaction","en","doctoral thesis","","","","","","","","2015-03-05","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:35bc63d3-c949-48da-8f26-9100836e7c45","http://resolver.tudelft.nl/uuid:35bc63d3-c949-48da-8f26-9100836e7c45","Aerosol direct radiative effect of smoke over clouds over the southeast Atlantic Ocean from 2006 to 2009","De Graaf, M.; Bellouin, N.; Tilstra, L.G.; Haywood, J.; Stammes, P.","","2014","The aerosol direct radiative effect (DRE) of African smoke was analyzed in cloud scenes over the southeast Atlantic Ocean, using Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite observations and Hadley Centre Global Environmental Model version 2 (HadGEM2) climate model simulations. The observed mean DRE was about 30–35 W m?2 in August and September 2006–2009. In some years, short episodes of high-aerosol DRE can be observed, due to high-aerosol loadings, while in other years the loadings are lower but more prolonged. Climate models that use evenly distributed monthly averaged emission fields will not reproduce these high-aerosol loadings. Furthermore, the simulated monthly mean aerosol DRE in HadGEM2 is only about 6?W m?2 in August. The difference with SCIAMACHY mean observations can be partly explained by an underestimation of the aerosol absorption Ångström exponent in the ultraviolet. However, the subsequent increase of aerosol DRE simulation by about 20% is not enough to explain the observed discrepancy between simulations and observations.","clouds; aerosols; climate change; remote sensing","en","journal article","American Geophysical Union","","","","","","","2015-05-11","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:ae587df2-905d-4746-b4ae-2c40a649fc58","http://resolver.tudelft.nl/uuid:ae587df2-905d-4746-b4ae-2c40a649fc58","Multi-sensor remote sensing parameterization of heat fluxes over heterogeneous land surfaces","Faivre, R.D.","Menenti, M. (promotor); Nerry, F. (promotor); Jia, L. (promotor)","2014","The parameterization of heat transfer by remote sensing, and based on SEBS scheme for turbulent heat fluxes retrieval, already proved to be very convenient for estimating evapotranspiration (ET) over homogeneous land surfaces. However, the use of such a method over heterogeneous landscapes (e.g. semi-arid regions or agricultural land) becomes more difficult, since the principle of similarity theory is compromised by the presence of different heat sources with various heights. This thesis aims at first to propose and evaluate some models based on vegetation geometry for retrieving the surface roughness length for momentum transfer (z0m), which is a key parameter in the characterization of heat transfer. Such an investigation can only be led at a small scale with very-high resolution remote sensing data, for a precise description of the land surface. Therefore, the second aspect of this work is to determine how to address the characterization of heat transfer for regional studies. Then, the reliability of SEBS for estimating turbulent heat fluxes at large spatial and temporal scales has been evaluated. To do so, the Multi-Scale SEBS approach (MSSEBS) has been implemented for a 2.4 million km2 area including the Tibetan Plateau and the headwaters of the major rivers of East and South Asia. The addition of gap-filled hourly FY-2 LST data to advanced daily averaged net radiation and land surface parameters, allows to compute time-series of land surface ET over the Tibetan Plateau during the period 2008-2010, and on a daily basis.","optical remote sensing; heterogeneous land surfaces; surface energy balance; heat transfer; evapotranspiration; roughness length; LIDAR; meso-scale atmospheric model; spatial and temporal resolutions","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Geoscience and Remote Sensing","","","",""
"uuid:eccac0ca-ae79-4a49-8c5a-c60aada6cb5a","http://resolver.tudelft.nl/uuid:eccac0ca-ae79-4a49-8c5a-c60aada6cb5a","Earth observation based assessment of the water production and water consumption of Nile basin agro-ecosystems","Bastiaanssen, W.G.M.; Karimi, P.; Rebelo, L.M.; Duan, Z.; Senay, G.; Muttuwatte, L.; Smakhtin, V.","","2014","The increasing competition for water resources requires a better understanding of flows, fluxes, stocks, and the services and benefits related to water consumption. This paper explains how public domain Earth Observation data based on Moderate Resolution Imaging Spectroradiometer (MODIS), Second Generation Meteosat (MSG), Tropical Rainfall Measurement Mission (TRMM) and various altimeter measurements can be used to estimate net water production (rainfall (P) > vapotranspiration (ET)) and net water consumption (ET > P) of Nile Basin agro-ecosystems. Rainfall data from TRMM and the Famine Early Warning System Network (FEWS-NET) RainFall Estimates (RFE) products were used in conjunction with actual evapotranspiration from the Operational Simplified Surface Energy Balance (SSEBop) and ETLook models. Water flows laterally between net water production and net water consumption areas as a result of runoff and withdrawals. This lateral flow between the 15 sub-basins of the Nile was estimated, and partitioned into stream flow and non-stream flow using the discharge data. A series of essential water metrics necessary for successful integrated water management are explained and computed. Net water withdrawal estimates (natural and humanly instigated) were assumed to be the difference between net rainfall (Pnet) and actual evapotranspiration (ET) and some first estimates of withdrawals—without flow meters—are provided. Groundwater-dependent ecosystems withdraw large volumes of groundwater, which exceed water withdrawals for the irrigation sector. There is a strong need for the development of more open-access Earth Observation databases, especially for information related to actual ET. The fluxes, flows and storage changes presented form the basis for a global framework to describe monthly and annual water accounts in ungauged river basins.","Nile Basin; evapotranspiration; rainfall; remote sensing; water production; water consumption; water accounting","en","journal article","MDPI","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:2a844dc9-0e89-43c7-a150-a89db0c8327b","http://resolver.tudelft.nl/uuid:2a844dc9-0e89-43c7-a150-a89db0c8327b","Retrieval of liquid water cloud properties from ground-based remote sensing observations","Knist, C.L.","Russchenberg, H.W.J. (promotor)","2014","Accurate ground-based remotely sensed microphysical and optical properties of liquid water clouds are essential references to validate satellite-observed cloud properties and to improve cloud parameterizations in weather and climate models. This requires the evaluation of algorithms for retrieval of cloud microphysical and optical properties using ground-based remote sensing observations, because there are large differences between the cloud property retrievals of various algorithms due to the differences in the applied retrieval theories, assumptions, retrieval inputs and constraints. This thesis focuses on three commonly used vertical cloud models for the parameterization of the in-cloud vertical structure in cloud property retrieval schemes. The objective is to explore the impact of the vertical cloud models on the computations of microphysical and optical properties of liquid water clouds and to evaluate their uncertainties. This information can help to improve current liquid water cloud property retrieval schemes and to increase the accuracy of the obtained cloud physical properties. A comparison of three algorithms with different vertical cloud models for the retrieval of liquid water cloud microphysical and optical properties is performed. In the first algorithm, the vertical structure of the cloud is parameterized as being vertically homogeneous (Vertically Uniform, VU). In the second algorithm, the used vertical cloud model originates from an adiabatic model (Scaled Adiabatic Stratified, SAS) and the third algorithm relies on a vertical model, which considers the impact of cloud top entrainment mixing processes on the cloud microphysical properties (Homogenous-Mixing, HM). All three algorithms use observations of the cloud radar reflectivity, the microwave radiometer obtained liquid water path (LWP) and the cloud geometrical thickness from lidar and cloud radar. They require a priori assumptions on the cloud droplet size distribution (DSD). Hence, the gamma function is used to parametrize the DSDs and possible values for the gamma DSD shape parameter are evaluated from reanalyzed in-situ observations. All three algorithms investigated here retrieve vertical profiles of the liquid water content (LWC), the droplet concentration, the effective radius, the visible optical extinction and the visible optical depth. The differences between the cloud property retrievals of each algorithm are explained on the basis of remote sensing observations that appear to be typical for low-level water clouds. The results of the VU cloud model per se lack detailed information on the vertical distribution of the cloud property retrievals. Under adiabatic conditions, the retrievals of the SAS and the HM models are equivalent, while the vertical distributions of the LWC, the effective radius and the optical extinction differ substantially under non-adiabatic conditions, especially at the cloud boundaries. The droplet concentrations of the SAS and HM models are very close to each other for both conditions. The model of uniform cloud properties yields values of the droplet concentration that are 25% lower than those from the models of non-uniform cloud properties. Interestingly, the differences between the cloud microphysical properties lead to very similar values of the retrieved visible optical depths. Sensitivity and error analyses suggest that the droplet concentration retrieval is generally most strongly affected by errors in the radar reflectivity and the LWP, while the retrievals of the effective radius are most robust in all three models. The retrievals of the optical depth and the effective radius are less affected by the variations in the DSD shape parameter as compared to the impact of the errors in observations. In contrast, the droplet concentration is more sensitive to changes in the gamma DSD shape parameter. Consequently the DSD shape parameter should be known a priori with reasonable precision. In order to evaluate the validity of the cloud property retrievals, the three algorithms are applied to synthetic surface remote sensing observations of a modeled liquid water cloud layer. The retrievals are compared with the physical properties of the modeled cloud layer as a function of the cloud height. Applying the algorithms to the best estimate “observations” and the assumed value for the DSD shape parameter leads to consistent HM model cloud property retrievals. In turn, significant overestimations of the SAS model LWC (50%) and the effective radius (10%) occur at cloud top where the SAS model retrieves the maximum values in the profiles. In all layers below the cloud top, the SAS cloud model retrievals of the LWC and the effective radius are very close to the modeled ones, because the true properties are increasing nearly adiabatically. As expected, the differences in the LWC and the effective radius profiles are largest upon the application of the VU model, which significantly overestimates both properties in the lower levels and underestimates them in the upper height levels. The very simple assumption that all cloud properties are uniformly distributed leads to a significant underestimation of the droplet concentration by about 20%. The SAS model droplet concentration is only slightly overestimated by 7%. Nevertheless, all cloud model retrievals of the optical depth agree well with those of the modeled cloud layer. To evaluate the performance of the cloud property retrievals obtained from real remote sensing observations, a broadband shortwave (SW) radiation closure analysis is performed for a selected water cloud case study. The SW fluxes at the surface calculated on the basis of the cloud properties of VU, SAS and HM models agree well with the surface radiation observations. The mean difference between the simulated and the measured SW fluxes is 2 W/m2 to 5 W/m2 with a standard deviation of 13W/m2. The uncertainty in the simulated fluxes can be explained by the uncertainty in the LWC and the effective radius due to errors in the LWP, the reflectivity and the assumption on the gamma DSD shape parameter. The three presented retrieval methods provide reliable cloud optical depth values for the selected water cloud case study. The different vertical distributions of the LWC and the effective radius, as well as differences in the droplet concentration, have a minor effect on simulating SW fluxes, because they lead to similar values of the optical depth. The present work shows that the liquid water cloud property retrievals obtained from the remote sensing observations depend on the model that is used to describe the vertical cloud structure. It shows that systematic deviations between the microphysical cloud properties of the VU, SAS and HM cloud models exist, especially regarding the droplet concentration, the LWC, the effective radius and the optical extinction at the cloud boundaries. The cloud microphysical properties estimated using the HM model parametrization show the best performance. The SAS cloud model can represent the vertically resolved microphysical properties well if they are very close to being adiabatic. Clearly, there are significant deviations in the cloud microphysics from the clouds that are parameterized as being vertically homogeneous (VU model). The different combinations of the microphysical properties in the three models lead to almost equivalent VU, SAS and HM optical depth retrievals, which agree well with the values of the modeled liquid water cloud. They are all able to reproduce the surface shortwave broadband radiative flux. However, by modeling clouds as being vertically homogeneous, sufficient accuracy in both the microphysical and the optical property retrievals cannot be achieved.","liquid water cloud properties; remote sensing; radiation","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Geoscience and Remote Sensing","","","",""
"uuid:fa7f157e-b63c-496c-85b8-fa8941752824","http://resolver.tudelft.nl/uuid:fa7f157e-b63c-496c-85b8-fa8941752824","Monitoring of irrigation schemes by remote sensing: Phenology versus retrieval of biophysical variables","Akdim, N.; Alfieri, S.M.; Habibi, A.; Choukri, A.; Cheruiyot, E.K.; Labbassi, K.; Menenti, M.","","2014","The appraisal of crop water requirements (CWR) is crucial for the management of water resources, especially in arid and semi-arid regions where irrigation represents the largest consumer of water, such as the Doukkala area, western Morocco. Simple and (semi) empirical approaches have been applied to estimate CWR: the first one is called Kc-NDVI method, based on the correlation between the Normalized Difference Vegetation Index (NDVI) and the crop coefficient (Kc); the second one is the analytical approach based on the direct application of the Penman-Monteith equation with reflectance-based estimates of canopy biophysical variables, such as surface albedo (r), leaf area index (LAI) and crop height (hc). A time series of high spatial resolution RapidEye (REIS), SPOT4 (HRVIR1) and Landsat 8 (OLI) images acquired during the 2012/2013 agricultural season has been used to assess the spatial and temporal variability of crop evapotranspiration ETc and biophysical variables. The validation using the dual crop coefficient approach (Kcb) showed that the satellite-based estimates of daily ETc were in good agreement with ground-based ETc, i.e., R2 = 0.75 and RMSE = 0.79 versus R2 = 0.73 and RMSE = 0.89 for the Kc-NDVI, respective of the analytical approach. The assessment of irrigation performance in terms of adequacy between water requirements and allocations showed that CWR were much larger than allocated surface water for the entire area, with this difference being small at the beginning of the growing season. Even smaller differences were observed between surface water allocations and Irrigation Water Requirements (IWR) throughout the irrigation season. Finally, surface water allocations were rather close to Net Irrigation Water Requirements (NIWR).","remote sensing; crop water requirements; irrigation performance; semi-arid climate; biophysical variables","en","journal article","MDPI","","","","","","","","Civil Engineering and Geosciences","Geoscience and Remote Sensing","","","",""
"uuid:3e51a4d9-bfd8-49c0-8100-73fb46bdebc2","http://resolver.tudelft.nl/uuid:3e51a4d9-bfd8-49c0-8100-73fb46bdebc2","Water Accounting Plus for Water Resources Reporting and River Basin Planning","Karimi, P.","Bastiaanssen, W. (promotor)","2014","This thesis introduces Water Accounting Plus (WA+), which is a new framework designed to provide explicit spatial information on water depletion and net withdrawal processes in complex river basins. WA+ is a simple, yet comprehensive and understandable water accounting framework that provides a standardized way of data collection and a presentation system that describes the overall land and water management situation in complex river basins. WA+ tracks water depletions rather than withdrawals and it goes past flow and run-off accounting. Rainfall is a recognized key hydrological process in WA+, and only a portion of total rainfall translates to stream flows and ground water recharge. A significant portion of the rainfall is directly depleted by natural processes such as ET from natural vegetation or rainfed plantations and crops. These natural water depletions bring about economic benefits and provide many services. Hence, by accounting only for run-off these benefits and uses of water will be discounted and the full picture on water flows and the gains will be distorted. WA+ explicitly recognizes the influence of land use on the water cycle and provides the link between water balance, land use and water use as well as management options to modify it, by grouping land use classes with common management characteristics. Information on water supply, water depletion processes, beneficial and non-beneficial depletion, biomass production, water and land productivity, and water withdrawals and reuse are presented in WA+. Land use is also central in reducing greenhouse gas emissions and other new approaches related to climate smart agriculture. In an effort to reduce greenhouse gas emissions, many countries also study the carbon accounts of rural areas. The WA+ framework improves understanding of the current state of a basin, issues, future challenges, and improvement opportunities. It provides the information that will help managers to make the basin more climate secure and to adapt to periods of droughts and floods. It can be used to monitor changes in a basin’s water resources situation and to assess the impacts of future interventions such as large scale land use change and expanding irrigated agriculture. To ensure global applicability of WA+ the framework is designed to primarily use data from open access satellite measurements. To showcase WA+ application, this thesis presents a case study from the Indus Basin. This pilot study demonstrates how the WA+ framework can be implemented to provide much-needed explicit information on the water resources situation, depletion, and productivity, in a systematic way by using minimum ground measured data and how the accounting results can be used to identify weaknesses, strengths, and opportunities. The accounting results show that the Indus basin is nearly a closed basin in which more than 95% of the available water is depleted while half of the water depletion is through processes that produce very little or no benefits, i.e. non-beneficial depletion. The majority of these non-beneficial depletion occurs via excessive soil evaporation of shallow water table areas. Hence, large amounts of valuable groundwater resources are vaporized non-beneficially into the atmosphere. The results also show that total annual water depletion in the basin plus outflows exceeds total precipitation. This situation has resulted in reduction in storage, especially groundwater storage. Such a fast decline in groundwater storage may have major implications for the sustainability of the basin. Not only it becomes an environmental crisis, also the food security is at danger. Scenario analysis show - based on a single year analysis - that through decreasing wasteful soil evaporation in agricultural areas, particularly in irrigated land an amount of 37.8 km3 can be saved. If interventions are not timely implemented, retirement of irrigated land seems unavoidable. The WA+ sheets were deemed useful to understand the impact of certain interventions. WA+ uses satellite measurements of land and water use data. All satellite data parameters have some level of uncertainty and error that needs to be taken into account because satellites are measuring hydrological processes indirectly. The errors in large water volumes (i.e. rainfall and ET) may result in large errors in river and aquifer flows. Thus the reliability of satellite measurements of land and water use data is investigated in this thesis. A comprehensive literature review on accuracy of the main satellite based estimates used in WA+, namely ET, rainfall, and land use land cover was conducted. For each parameter an error probability distribution function (PDF) is fitted from peer reviewed articles. The results show that the mean absolute error for satellite-based estimates of ET, rainfall, and land use classification are 5.4%, 18.5 %, 14.6% respectively. The largest error is thus associated with rainfall. Bias correction and local calibration of global and regional rainfall products seem to improve the quality of the data layers. In contrast to rainfall, the error in satellite-based ET is relatively small. ET is a vital component of the hydrological cycle. Results show that remotely sensed ET is reliable enough to be used both as input into distributed hydrological models, and as a means to calibrate the simulations. Nonetheless, despite the existing potential and accuracy, satellite-based ET is under-utilized in hydrological studies. Contributing factors are presumably the difficulty to access and acquire reliable ET data through the public domain, and the difficulty to compare it with reliable field data. The land use classifications come with an overall error of 14.6%. This level of accuracy, although acceptable, calls for improvements given the wide use of these maps. Another important issue is the need for a new type of land use mapping dedicated to agricultural and river basin water management issues. Currently, most legends are meant to describe ecosystems, instead of classes with differences in water management. Furthermore this thesis explores the impact of the uncertainty of the satellite measurement on the reliability of WA+ outputs. Predictive uncertainty of WA+ outputs was studied for the Awash River basin in Ethiopia. The Monte Carlo (MC) technique that is based on selecting numbers randomly from a pre-defined probabilistic distribution was used for stochastic simulation of WA+ outputs. The simulation was repeated 1,000 times for three years (2009, 2010, and 2011). The results of this exercise show that the stochastic mean of the majority of WA+ parameters and performance indicators are within 1% deviation from the original value. This shows that stochastic simulation can be used as part of a standard procedure to produce water accounts with WA+. There are two main advantages pertaining to the MC technique. Firstly, incorporation and acknowledgement of input data errors in producing water accounts. Secondly, the possibility to estimate and report on the error band width that surrounds every WA+ output. The latter is of essential value to informed decision making, as it enables users to better understand the error margin that is associated with the generated information. The goal is to separate reliable information from those that have low reliability. In such a way, outputs with a high error margin, low reliability, will be identified and it is recommended that they should not be used to formulate policy decisions. WA+ has triggered a wider discussion on using the framework for analyzing complex river basins, especially when data is scarce. This holds true especially for developing countries where the required data collection and archiving processes are insufficient for creating clearly defined alterative solutions for decision makers. A simple WA+ system based on earth observation data is thus a good first step in the right direction. A multi-institutional water accounting data repository is under development that is endorsed by IWMI, UNESCO-IHE and FAO. This platform, WaterAccounting.org, will be based on routine satellite data, data from hydrological models, and other open access global and regional data sources. The platform will provide information by sectors (i.e. agriculture, environment) on the sources of water use (i.e. surface water and groundwater), geographical water scarcities (i.e. local demand and supply), utilizable water flows (i.e. local actual flows and reserved flows), and the sustainability of the water services to environment, food security, energy, economy and domestic use.","water accounting; water productivity; evapotranspiration; remote sensing; utilized flow","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:58f584c3-5f20-4cb2-8314-aae75f1b9f00","http://resolver.tudelft.nl/uuid:58f584c3-5f20-4cb2-8314-aae75f1b9f00","Remotely sensed monitoring of small reservoir dynamics: A Bayesian approach","Eilander, D.M.; Annor, F.O.; Iannini, L.; Van de Giesen, N.C.","","2014","Multipurpose small reservoirs are important for livelihoods in rural semi-arid regions. To manage and plan these reservoirs and to assess their hydrological impact at a river basin scale, it is important to monitor their water storage dynamics. This paper introduces a Bayesian approach for monitoring small reservoirs with radar satellite images. The newly developed growing Bayesian classifier has a high degree of automation, can readily be extended with auxiliary information and reduces the confusion error to the land-water boundary pixels. A case study has been performed in the Upper East Region of Ghana, based on Radarsat-2 data from November 2012 until April 2013. Results show that the growing Bayesian classifier can deal with the spatial and temporal variability in synthetic aperture radar (SAR) backscatter intensities from small reservoirs. Due to its ability to incorporate auxiliary information, the algorithm is able to delineate open water from SAR imagery with a low land-water contrast in the case of wind-induced Bragg scattering or limited vegetation on the land surrounding a small reservoir.","small reservoir; delineation; image classification; naive Bayesian classification; polarimetry; remote sensing; SAR; semi arid; backscatter analysis","en","journal article","","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:208477f0-1b15-4c54-a509-de5353bc33ff","http://resolver.tudelft.nl/uuid:208477f0-1b15-4c54-a509-de5353bc33ff","Mapping evapotranspiration trends using MODIS and SEBAL model in a data scarce and heterogeneous landscape in Eastern Africa","Kiptala, J.K.; Mohamedi, Y.; Mul, M.L.; Van der Zaag, P.","","2013","Evapotranspiration (ET) accounts for a substantial amount of the water use in river basins particular in the tropics and arid regions. However, accurate estimation still remains a challenge especially in large spatially heterogeneous and data scarce areas including the Upper Pangani River Basin in Eastern Africa. Using multitemporal Moderate-resolution Imaging Spectroradiometer (MODIS) and Surface Energy Balance Algorithm of Land (SEBAL) model, 138 images were analyzed at 250 m, 8 day scales to estimate actual ET for 16 land use types for the period 2008–2010. A good agreement was attained for the SEBAL results from various validations. For open water evaporation, the estimated ET for Nyumba ya Mungu (NyM) reservoir showed a good correlations (R?=?0.95; R2?=?0.91; Mean Absolute Error (MAE) and Root Means Square Error (RMSE) of less than 5%) to pan evaporation using an optimized pan coefficient of 0.81. An absolute relative error of 2% was also achieved from the mean annual water balance estimates of the reservoir. The estimated ET for various agricultural land uses indicated a consistent pattern with the seasonal variability of the crop coefficient (Kc) based on Penman-Monteith equation. In addition, ET estimates for the mountainous areas has been significantly suppressed at the higher elevations (above 2300 m a.s.l.), which is consistent with the decrease in potential evaporation. The calculated surface outflow (Qs) through a water balance analysis resulted in a bias of 12% to the observed discharge at the outlet of the river basin. The bias was within 13% uncertainty range at 95% confidence interval for Qs. SEBAL ET estimates were also compared with global ET from MODIS 16 algorithm (R?=?0.74; R2?=?0.32; RMSE of 34% and MAE of 28%) and comparatively significant in variance at 95% confidence level. The interseasonal and intraseasonal ET fluxes derived have shown the level of water use for various land use types under different climate conditions. The evaporative water use in the river basin accounted for 94% to the annual precipitation for the period of study. The results have a potential for use in hydrological analysis and water accounting.","evapotranspiration; MODIS 16; SEBAL; remote sensing; Pangani River Basin","en","journal article","American Geophysical Union","","","","","","","2014-06-17","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:e5f10f98-4224-4f07-9cb3-00fd7820e41f","http://resolver.tudelft.nl/uuid:e5f10f98-4224-4f07-9cb3-00fd7820e41f","Data Extraction from Social Networks for Urban Analyses: Combining Space Syntax and user-generated data analysis on Lisbon","Fiorito, S.; Orsi, F.; Serdoura, F.M.; Ferreira, V.","","2013","The present work constitutes the first stage of an ongoing research on the interaction between morphological characteristics of the urban fabric and the amount of social activity in such spaces. In order to analyze such correlation, the current research links together two different field of studies: Space Syntax on one side, for the morphological analysis of the spatial configuration of the urban fabric, and a remote sensing study about social activity in the analyzed urban context, on the other. Data extracted from location-based online Social Networks databases (e.g. Foursquare) are employed in order to perform such survey. The resulting methodology constitutes an early attempt to set a novel approach to the study of the relationships between the morphological and configurational characteristics of urban systems and actual human dynamics in urban contexts.","Space Syntax; urban morphology; remote sensing; social networks; urban dynamics","en","conference paper","","","","","","","","","","","","","",""
"uuid:e09bb23d-d519-4d44-bdcd-fca2d2f98866","http://resolver.tudelft.nl/uuid:e09bb23d-d519-4d44-bdcd-fca2d2f98866","Parameterization of Surface Roughness Based on ICESat/GLAS Full Waveforms: A Case Study on the Tibetan Plateau","Shi, J.; Menenti, M.; Lindenbergh, R.","","2013","Glaciers in the Tibetan mountains are expected to be sensitive to turbulent sensible and latent heat fluxes. One of the most significant factors of the energy exchange between the atmospheric boundary layer and the glacier is the roughness of the glacier surface. However, methods to parameterize this roughness for glacier surfaces in remote regions are not well known. In this paper, the authors use the data acquired by Ice, Cloud, and Land Elevation Satellite (ICESat)/Geoscience Laser Altimeter System (GLAS) laser altimetry from February 2003 to November 2004 along several tracks over glaciers of the Nyainqentanglha range in central Tibet. The authors make a study of the waveforms measured by the ICESat/GLAS laser system over mountainous and glacial areas. The surface characteristics are evaluated within laser footprints over the glacier outlines based on the glaciological inventory of the Tibetan Plateau constructed by the Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), Chinese Academy of Sciences. For this purpose, the authors extract waveform parameters: the waveform width, the number of modes, and the RMS width of the waveform. These parameters are compared with surface slope and roughness obtained from the Advanced Spaceborne Thermal Emission and Reflection Radar (ASTER) Global Digital Elevation Model (GDEM). Through this analysis, the impact of morphology on the returned laser waveform is shown for the Nyainq^entanglha range. The roughness and the slope of the surface can be quite significant and may contribute from several meters to tens of meters to the pulse extent. The waveform analysis results indicate that the received waveforms are capable representations of surface relief within the GLAS footprints.","altimetry; lidars; lidar observations; remote sensing","en","journal article","American Meteorological Society","","","","","","","2014-03-01","Civil Engineering and Geosciences","Geoscience and Remote Sensing","","","",""
"uuid:92e94609-ec37-43e5-ad01-3817756d30f6","http://resolver.tudelft.nl/uuid:92e94609-ec37-43e5-ad01-3817756d30f6","Establishing a sea bottom model by applying a multi-sensor acoustic remote sensing approach","Siemes, K.","Simons, D.G. (promotor); Hermand, J.P.O.F.G. (promotor)","2013","Detailed information about the oceanic environment is essential for many applications in the field of marine geology, marine biology, coastal engineering, and marine operations. Especially, knowledge of the properties of the sediment body is often required. Acoustic remote sensing techniques have become highly attractive for classifying the sea bottom and for mapping the sediment properties, due to their high coverage capabilities and low costs compared to common sampling methods. In the last decades, a number of different acoustic devices and related techniques for analyzing their signals have evolved. Each sensor has its specific application due to limitations in the frequency range and resolution. In practice, often a single acoustic tool is chosen based on the current application, supported by other non-acoustic data where required. However, different acoustic remote sensing techniques can supplement each other, as shown in this thesis. Even more, a combination of complementary approaches can contribute to the proper understanding of sound propagation, which is essential when using sound for environmental classification purposes. This includes the knowledge of the relation between acoustics and sediment properties, the focus of this thesis. Providing a detailed three dimensional picture of the sea bottom sediments that allows for gaining maximum insight into this relation is aimed at. Chapters 4 and 5 are adapted from published work, with permission: DOI:10.1121/1.3569718 (link: http://asadl.org/jasa/resource/1/jasman/v129/i5/p2878_s1) and DOI:10.1109/JOE.2010.2066711 (link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=5618582&queryText%3Dsiemes) In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of the TU Delft's products or services.","acoustic remote sensing; marine sediment; sub-seafloor; environmental characterization; single-beam echosounder; multibeam echosounder; seismic profiling; chirp; geoacoustic inversion; phenomenological approach; model-based approach; density; compressional sound speed; acoustic attenuation; sediment samples; fine-grained sediments; gas","en","doctoral thesis","Uitgeverij BOXPress","","","","","","","2015-12-31","Aerospace Engineering","Control and Operations","","","",""
"uuid:8dee0408-1e71-4899-b372-51bfd8a52895","http://resolver.tudelft.nl/uuid:8dee0408-1e71-4899-b372-51bfd8a52895","Rip current predictions through model-data assimilation on two distinct beaches","Van Dongeren, A.; Van Ormondt, M.; Sembiring, L.; Sasso, R.; Austin, M.; Briere, C.; Swinkels, C.; Roelvink, J.A.; Van Thiel De Vries, J.S.M.","","2013","This paper describes the development of a physics-based rip current prediction system called CoSMoS. This system consists of a hydrodynamic prediction system which is composed of a train of surge and wave models from the global scale to the scale of a beach resort (order kilometers). For the beach resort scale model, it is of utmost importance to use a recent measured or remote-sensed estimated bathymetry in order to accurately predict morphologically-controlled rip currents. To obtain bathymetry estimates, the Beach Wizard system which makes use of Argus video data is applied to the macro-tidal coast of Perranporth UK and the meso-tidal coast of Egmond aan Zee, the Netherlands. The results for the UK site show that while the Brier Skill Scores of the estimated bathymetry are low, the resultant rip current location, strength and timing are well-predicted. For the Egmond case, the system produces good estimates of the bathymetry and of the rip current parameters. Finally, we demonstrate the potential and form of rip current warnings based on the application of the CoSMoS system for Egmond aan Zee.","rip currents; rip current predictions; numerical modeling; remote sensing; Beach Wizard; XBeach; Egmond aan Zee; Perranporth","en","conference paper","Bordeaux University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:fe4b009f-3c35-49c9-87e0-e0ee24517dd0","http://resolver.tudelft.nl/uuid:fe4b009f-3c35-49c9-87e0-e0ee24517dd0","Monitoring morphology of the sand engine leeside using Argus' cBathy","Wengrove, M.E.; Henriquez, M.; De Schipper, M.A.; Holman, R.; Stive, M.J.F.","","2013","The Sand Engine is a mega-nourishment constructed in 2011 with the purpose of replenishing the surrounding southern Dutch coast by exploiting the strength of local alongshore currents for the next 20 years. Long term monitoring of the Sand Engine depends upon remote sensing coupled with in-situ measurements due to both its large spatial and temporal scales and variability. Herein, emphasis is made upon quantitatively and qualitatively observing the effects of this mega-nourishment upon its leeward side in the direction of the predominant alongshore current. One of the first applications of cBathy along the Dutch coast shows promising results for this remote technique to capture morphodynamics within the area over the coming years. cBathy is an algorithm developed to make estimations of nearshore bathymetry based upon the celerity of the propagating wave field extracted from Argus coastal images. So far, analysis shows that the Dutch wave climate variability influences hourly cBathy depth approximations, however running average depth estimations yield small deviation compared with a measured ground truth bathymetry of the area.","morphology; remote sensing; alongshore currents; beach nourishment; cBathy; Argus","en","conference paper","Bordeaux University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f2fbb88c-dde8-479e-a595-6288a77019c1","http://resolver.tudelft.nl/uuid:f2fbb88c-dde8-479e-a595-6288a77019c1","Monitoring of beach surface properties with remote sensing","Hoonhout, B.M.; De Vries, S.; Baart, F.; Van Thiel De Vries, J.S.M.; Van der Weerd, L.; Wijnberg, K.","","2013","Existing aeolian transport formulae tend to overestimate the sediment transport volumes in coastal environments. Supply limiting factors like moisture content, shell patches, sediment sorting, vegetation and morphological features are believed to explain these overestimations. These supply limitations act on a variety of spatio-temporal scales that hinder relating supply and transport. Probabilistic graphical models (PGM) can be used to cope with the variety and complexity of these relations. A long term measurement campaign is started to feed such probabilistic models with data on the complex interaction between supply limitations and their influence on coastal aeolian transport and subsequently dune growth. The variety of spatio-temporal scales involved in supply limited coastal aeolian transport generally is not fully captured by traditional measurement techniques. This campaign uses, apart from traditional in-situ techniques, remote sensing and image analysis techniques to cover a variety of spatio-temporal scales that are related to coastal aeolian transport and supply limitations in particular. We aim to construct a dataset that contains long term and high resolution grid data as well as binary time series and a variety of in-situ measurements on (local) wind forcing, beach surface properties and aeolian transport. The probabilistic graphical models will be used to consolidate the dataset towards practical instruments to model the large scale and long term (LSLT) behavior we are finally interested in.","aeolian transport; supply limitations; remote sensing; moisture; sediment sorting","en","conference paper","Bordeaux University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7d1f7672-5d97-4b32-9c44-ad0bcc259b82","http://resolver.tudelft.nl/uuid:7d1f7672-5d97-4b32-9c44-ad0bcc259b82","LaBr3 gamma?ray spectrometers for space applications","Quarati, F.G.A.","Dorenbos, P. (promotor)","2013","LaBr3 has been developed into large volume scintillator detectors within an ESA and TU Delft programme during this thesis work. The programme, which aimed at the space applications of LaBr3, also led to extensive experiments within a collaborative framework which included representatives for all the development aspects, i.e., from crystal growers to scintillator materials researchers to final users. The research presented in this thesis is the result from my in-depth involvement in that programme. The thesis’s first achievement was the assessment of the radiation tolerance of LaBr3 in Chapter 2. In fact, BepiColombo’s payload must withstand proton fluence as high as 6 × 1010 protons/cm2 to guarantee successful scientific observations. It was found that LaBr3 exceeds that requirement without substantial deterioration of its performance. Such an ability, together with the relative low mass and power resources demand that is typical for scintillation detectors, has made LaBr3 the choice for the BepiColombo onboard gamma-ray spectrometer. LaBr3 detectors is a new technology, and experimental studies were necessary to support instrument design and optimization for space applications. The deterioration of performance with increased detector size has been closely monitored in Chapter 4. The limits of LaBr3 application were also studied and, with the use of synchrotron radiation, it was found that LaBr3 is a non-ideal scintillator for photon detection in the X-ray domain, below 100 keV. The same technique proved to be an effective tool for non-proportionality studies and extensively applied by TU Delft colleagues. Scintillation readout of LaBr3 pushes the PMT to its operational limits. Experimental campaigns were performed to study the response to high energy gamma-rays as reported in Chapter 5. This gave a unique opportunity to observe the correlation between gamma-ray energy and energy resolution up to 15 MeV. In addition, it offered the benchmark to verify in flight energy calibration capability. As demonstrated in Chapter 5 of this thesis, results are satisfactory, which makes LaBr3 applicable for the BepiColombo mission. However the results also suggest to initiate new programmes to develop alternative scintillation readout techniques as with silicon Photomultipliers and Silicon Drift Detectors. The major disadvantage of LaBr3 is a lack of sensitivity because of the intrinsic activity generated by 138La decays, in particular at 1.4 MeV, which is relevant for the detection of 40K. Full characterization of this activity in Chapter 6 led to the first experimental determination of the low-energy end of a second-order-unique-forbidden ? continuum. A deviation with the standard theoretical models on nuclear decay was found of which an explanation is not at hand yet. Development of alternative materials able to challenge LaBr3 for energy resolution and efficiency but with much reduced intrinsic activity is presently ongoing. A selection of recent results achieved with CeBr3 spectrometers were presented in Chapter 7, showing that CeBr3 detection sensitivity at 1.4 MeV is about 8 times higher compared to LaBr3.","gamma-ray spectroscopy; planetary remote sensing; scintillator detectors","en","doctoral thesis","Uitgeverij BOXPress","","","","","","","","Applied Sciences","Radiation Science & Technology","","","",""
"uuid:543bf257-4ff6-4d25-954a-aa36627d0854","http://resolver.tudelft.nl/uuid:543bf257-4ff6-4d25-954a-aa36627d0854","Robotization in Seismic Acquisition","Blacquière, G.; Berkhout, A.J.","","2013","The amount of sources and detectors in the seismic method follows ""Moore’s Law of seismic data acquisition"", i.e., it increases approximately by a factor of 10 every 10 years. Therefore automation is unavoidable, leading to robotization of seismic data acquisition. Recently, we introduced a new source concept that replaces today’s complex, local, broadband source arrays by distributed source arrays of simple, narrow-band sources (DSAs). This concept is not only most favorable for blended acquisition, it is also very suitable to decentralize the entire seismic acquisition system. E.g., think of a relatively large number of autonomous shooting boats (N), each boat equipped with a simple, narrow-band source and a local vector cable with M sensors. Together, all narrow-band sources illuminate the subsurface with an incoherent wavefield that is characterized by a high spatial and temporal bandwidth. Since each of the N sources fires into the M sensors of each of the N cables, the number of acquired multi-offset, multi-azimuth traces equals MN2! On land, data collection could be automated by introducing wireless geophones to be planted by robots. However, a far more interesting option is to use advanced airborne sensing technology, for simultaneously recording the seismic response of an entire area, supplemented with a sparse distribution of high-quality seismic sensors for calibration purposes. In our view such calibration sensors are ’unmanned flying objects’. In the Delphi Consortium, recently an innovation project on the robotization of seismic acquisition has started.","acquisition; land; marine; remote sensing","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:05027aa3-9536-4f05-a703-9fe0496333c6","http://resolver.tudelft.nl/uuid:05027aa3-9536-4f05-a703-9fe0496333c6","Air quality over the Canadian oil sands: A first assessment using satellite observations","McLinden, C.A.; Fioletov, V.; Boersma, K.F.; Krotkov, N.; Sioris, C.E.; Veefkind, J.P.; Yang, K.","","2012","Results from the first assessment of air quality over the Canadian oil sands–one of the largest industrial undertakings in human history–using satellite remote sensing observations of two pollutants, nitrogen dioxide (NO2) and sulfur dioxide (SO2), are presented. High-resolution maps were created that revealed distinct enhancements in both species over an area (roughly 30 km × 50 km) of intensive surface mining at scales of a few kilometers. The magnitude of these enhancements, quantified in terms of total mass, are comparable to the largest seen in Canada from individual sources. The rate of increase in NO2between 2005 and 2010 was assessed at 10.4 ± 3.5%/year and resulted from increases both in local values as well as the spatial extent of the enhancement. This is broadly consistent with both surface-measurement trends and increases in annual bitumen production. An increase in SO2 was also found, but given larger uncertainties, it is not statistically significant.","NO2; SO2; oil sands; remote sensing","en","journal article","American Geophysical Union","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:fd060db1-d4a0-460e-b31e-03b70f05ae1d","http://resolver.tudelft.nl/uuid:fd060db1-d4a0-460e-b31e-03b70f05ae1d","Integrating GIS, remote sensing and mathematical modelling for surface water quality management in irrigated watersheds","Azab, A.M.","Price, R.K. (promotor)","2012","The intensive uses of limited water resources, the growing population rates and the various increasing human activities put high and continuous stresses on these resources. Major problems affecting the water quality of rivers, streams and lakes may arise from inadequately treated sewage, poor land use practices, inadequate controls on the discharges of industrial waste waters, uncontrolled poor agricultural practices, excessive use of fertilizers, and a lack of integrated watershed management. This study explores the impact of these pollution problems and the water quality degradation of Irrigated agricultural watersheds When the watersheds have a complex physical basis of interacting water bodies such as canals, drains and coastal lagoons as in the case of irrigated watersheds in coastal river Deltas, and when these environments are ‘data scarce environments’, the problems of managing water quality becomes more obvious and the need for reliable solutions becomes an urgent requirement. This study focused on the management of surface water quality problems in such watersheds and the importance of taking into consideration all the watershed components and the effects of pollution from the upstream canals on the downstream coastal lakes. In this study a generic framework for a (Water Quality Management Information System) is developed depending on the integration of physically based hydrodynamic and water quality models with GIS capabilities and the spatial and temporal capabilities of remote sensing in water quality modeling. The application is developed and tested for the Edko drainage catchment and shallow lake system in the western part of the Nile Delta, Egypt. The developed framework includes a hierarchy of modeling tools: a 1D-2D basic hydrodynamic model for a combined shallow lake-drainage system, a detailed 2D hydrodynamic model of the shallow lake, and a 2D water quality and eutrophication screening models for the lake system. The basic water quality model for the lake system simulates the main water quality parameters including the oxygen compounds, nutrients compounds, temperature, salinity and the total suspended matter (TSM). The complexity of the physical and ecological properties of the lake system implied the use of different methodologies for models calibration using remote sensing. The combination of remote sensing with mathematical modelling, for the calibration and verification of TSM and chlorophyll-concentrations in the shallow lake system showed reliable and successful results.","Watershed; shallow lakes; drainage; hydrodynamic modelling; water quality modelling; eutrophication; nutrients; Chla; remote sensing; calibration; information systems","en","doctoral thesis","CRC Press/Balkema","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:26845c1a-5248-48fc-9379-7c44d8f85c5b","http://resolver.tudelft.nl/uuid:26845c1a-5248-48fc-9379-7c44d8f85c5b","Surface and subsurface water from space: On the integration of microwave remote sensing observations with flood prediction systems","Matgen, P.","Savenije, H.H.G. (promotor)","2011","The technique of active microwave remote sensing has made much progress toward its high potential to monitor water storage changes in terrestrial surface and subsurface water bodies at various spatial and temporal scales. The number of studies demonstrating the support these data can offer in hydrological and hydraulic model building, model calibration and model updating is growing rapidly. While there is no doubt that this technological progress has already brought new insights into hydrology and hydraulics, there are still several issues that require attention. The questions to answer are: (1) How to add value to ‘raw’ remote sensing data for hydrological applications, (2) how to combine remote sensing techniques with hydrologic-hydraulic models for improved predictions, and (3) how to evolve irregular and intermittent remote sensing-based applications into systematic services? The first question deals with the adequate data processing to retrieve meaningful information about hydrological/hydraulic variables. Further, remote sensing-derived data are characterized by considerable uncertainty, which needs to be evaluated and clearly communicated to the users of such data. The second question deals with the effective integration of remote sensing-derived information and in situ data with adequate models, either offline for model building and calibration or online via assimilation for model updating. The third question focuses on an efficient production, processing and distribution of satellite data and the development of new services that may help to advance operational water resources management. This thesis deals with all three questions, with a clear focus on active microwave remote sensing and hydrological/hydraulic modeling.","microwave remote sensing; Synthetic Aperture Radar; data assimilation; hydrological modelling; hydraulic modelling; flood; soil moisture","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","Water Resources","","","",""
"uuid:7159276e-667c-42e5-9f65-432898b7012b","http://resolver.tudelft.nl/uuid:7159276e-667c-42e5-9f65-432898b7012b","Monitoring the extent of flooding: Based on a case study in Queensland","Thompson, R.J.; Van Oosterom, P.J.M.; Zlatanova, S.; Van de Giesen, N.C.; Goulevitch, B.","","2011","“Of droughts and flooding rains” (Dorothea Mackellar 1885-1968, “My Country”). The recent flooding in Queensland affected rural areas, mines, towns and cities including the state capital. Tracking such an event on a day-by day basis raises practical and theoretical issues. While this year’s floods captured world headlines, there is a major flooding event in Queensland about every second year. There are obvious costs resulting from serious flooding, and some can be reduced significantly if the public are reliably informed (whether to evacuate, what property to save, where to evacuate to, what route to take, where to store property). There are also indirect costs to be reduced by the dissemination of reliable information. For example, losses to the tourist industry caused by exaggerated reporting. The paper explores strategies to provide advice to the public by presenting: available raw imagery leaving users to make an interpretation, processed data with information for probable inundation, processed data overlaid with a quality mask indicating reliability, corrected data using a variety of sources, or combination of existing numerical flood models with topographic information to predict flood extent. The paper addresses various sensor products that can be used, their combination with flood modelling techniques, a historical record of inundations, direct measurements (river gauges, rainfall measurements, sensor webs etc.) and more diffuse inputs (crowd sourcing) to supply the best possible decision support information to the public.","flood extent; remote sensing; flood modelling; flood monitoring; decision support; Queensland floods","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","OTB Research Institute for the Built Environment","OTB Research","","","",""
"uuid:fc55594a-cb4e-4ddf-8a63-4b63146bccdb","http://resolver.tudelft.nl/uuid:fc55594a-cb4e-4ddf-8a63-4b63146bccdb","Automatic object recognition and change detection of urban trees","Van der Sande, C.J.","","2010","Monitoring of tree objects is relevant in many current policy issues and relate to the quality of the public space, municipal urban green management, management fees for green areas or Kyoto protocol reporting and all have one thing in common: the need for an up to date tree database. This study, part of the Tree and Image research project, developed a database-driven approach for object recognition and change detection using optical imagery including contextual data from urban tree databases and topographic data. Trees are 3D objects and vary in shape throughout the season. The tree is modelled in a 2D aerial image using the point location and species information. The tree model consists of a projected crown and shadow. These projections, polygons, are used to recognise the object with NDVI and texture parameters related to the ground surface derived from the topographic map and its neighbouring segments. This resulted in classifications of trees ‘still present’ or ‘disappeared’ with an overall accuracy of 85%. However, the errors of commission and omission were quite high due to the use of an early image with no full-grown crowns, resulting in difficult recognisable trees. Detected changes can be used for further human verification or directly serve as input for database management and decision making.","remote sensing; change detection; updating; segmentation; 3D; object oriented; urban; trees; database","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:a4882e51-6f1c-4d2e-84e1-b98732da183d","http://resolver.tudelft.nl/uuid:a4882e51-6f1c-4d2e-84e1-b98732da183d","Fire risk assessment: The role of hyperspectral remote sensing","Maffei, C.; Menenti, M.","","2010","The increasing demand for effective forest fire prevention instruments has faced operational and future Earth observation instruments with the challenge of producing updated and reliable maps of vegetation moisture. Various empirical band-ratio indexes have been proposed so far, based on multispectral remote sensing data, that have been found to be related to vegetation moisture expressed in terms of equivalent water thickness (EWT), which is defined as the weight of liquid water per unit leaf area. More sophisticated retrieval methodologies can be adopted when hyperspectral data are available, e.g. based on spectral curve fitting in selected water absorption bands or radiative transfer model inversion, allowing for better estimates of EWT. Problems arise with the evaluation of fuel moisture content (FMC), which is the percentage weight of water per unit of oven-dried leaf weight, due to its weak signal in vegetation spectrum. FMC is essential in fire models, and it is not interchangeable with EWT. Basing on simulated vegetation spectra, this study aims at demonstrating that hyperspectral images of vegetated areas can be effectively used to evaluate FMC with accuracies not achievable with multispectral data. To this purpose, radiative transfer models PROSPECT and SAILH have been used to simulate canopy reflectance. Vegetation spectra have then been convolved to hyperspectral data basing on the design specifications of a formerly planned ASI-CSA hyperspectral mission (JHM configuration C), similar to those of the forthcoming PRISMA. For comparison against multispectral instruments, measurements from the Operational Land Imager (OLI) have also been simulated. Two retrieval methods have been tested, based on spectral indexes and on partial least squares (PLS) regression. The latter methodology is particularly suited to analyse high-dimensional data. Results confirm that spectral indexes are good predictors of vegetation moisture expressed as EWT, but their performance in evaluating FMC is poor. By using PLS regression on hyperspectral data, a linear model can be built that accurately predicts FMC. No such result is achievable from OLI simulated data.","fire hazard; vegetation moisture; hyperspectral; remote sensing; PROSPECT; SAILH; PRISMA","en","conference paper","European Space Agency (ESA)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:a233f5ae-ea79-4166-848c-1861f8ea4da9","http://resolver.tudelft.nl/uuid:a233f5ae-ea79-4166-848c-1861f8ea4da9","Benchmarking water productivity in agriculture and the scope for improvement - remote sensing modelling from field to global scale","Zwart, S.J.","Bastiaanssen, W.G.M. (promotor)","2010","Agriculture is the largest consumer and water. In the context of an increasing population and less water available for the agricultural sector, the water productivity needs to be sustained or increased to secure food security. This study provides benchmark values for water productivity for the major crops globally. Data were obtained from a literature review of measured water productivity values from field experiments, whereas remote sensing and modelling were used to assess the water productivity of wheat on a regional and on a global scale. The SEBAL model was applied to obtain spatially distributed values of water productivity in eight irrigated wheat systems globally. The analysis showed that the scope for improvement is significant in several of these systems in China, Pakistan and India. A new model, WATPRO, was developed that was applied on a global scale to benchmark water productivity of wheat at the beginning of the millennium.","water productivity; remote sensing; wheat; rice; maize; cotton; global modelling; SEBAL; WATPRO","en","doctoral thesis","VSSD","","","","","","","2010-05-06","Civil Engineering and Geosciences","Watermanagement","","","",""
"uuid:743bd224-e72a-4d44-a878-f68e1495bef7","http://resolver.tudelft.nl/uuid:743bd224-e72a-4d44-a878-f68e1495bef7","Remote Sensing and Economic Indicators for Supporting Water Resources Management Decisions","Hellegers, P.J.G.J.; Soppe, R.; perry, C.J.; Bastiaanssen, W.G.M.","","2009","This paper demonstrates that combining spatial land surface data with socio-economic analysis provides a number of indicators to strengthen decision making in integrated water and environmental management. It provides a basis to: track current water consumption in the Inkomati Basin in South-Africa; adjust irrigation water management; select crop types; facilitate planning; estimate crop yields before harvesting, and consequently to forecast market price development. Remote sensing data and economic analysis can also be used to study the spatial distribution of water consumption as an indicator of equity in access to water resources. It even enables identification of farms that consume more irrigation water than formally allocated. Finally, it provides a basis to assess the cost-effectiveness of various ways to reduce agricultural water consumption. So, this approach is potentially useful for determining water consumption, refining water allocation policies, and determining the potential for water transfers through mechanisms such as water trading.","Remote sensing; Economic analysis; Cost-effectiveness; Spatial and temporal variability; Water consumption; Excess use; Opportunity costs","en","journal article","Springer Verlag","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:7a1959e6-1c52-4ff0-9411-56bd002225c3","http://resolver.tudelft.nl/uuid:7a1959e6-1c52-4ff0-9411-56bd002225c3","Calibration suspended sediment model Markermeer","Boderie, P.; Van Kessel, T.; De Boer, G.","","2009","In deze studie is een computermodel voor het Markermeer opgezet, ingeregeld en gevalideerd. Het model beschrijft dynamsch de stroming van water, waterpeilen, golven en slib in het water en in de bodem. Het model is gecalibreerd voorde periode augustus 2007 - april 2008 en gevalideerd voor de periode daarna tot september 2008. In deze periode zijn hoogfrequente meetgegevens voor twee meetpalen in het Markermeer beschikbaar. Onafhankelijk daarvan is het model gevalideerd aan de hand van remote sensing beelden voor het jaar 2006.","3D model; slib; bodemruwheid; remote-sensing; Markermeer; calibratie; validatie; meetpaal; Delft Cluster; CT04.44.11","nl","report","Delft Cluster","","","","","","","","","","","","",""
"uuid:81ef59db-f20d-4bc7-a539-e6f08f2cbd0a","http://resolver.tudelft.nl/uuid:81ef59db-f20d-4bc7-a539-e6f08f2cbd0a","Regional vegetation water effects on satellite soil moisture estimations for West Africa","Friesen, J.C.","Van de Giesen, N.C. (promotor)","2008","Soil moisture information is a vital parameter for water resources planning and food production. In particular for West Africa, where income largely depends on rainfed agriculture, reliable information on available soil water is required for modeling and prediction. Over large areas and, specifically, for data scarce regions, satellite soil moisture estimates are required to obtain reliable information on available soil water. This necessity for satellite-based soil moisture data has already resulted in recent and upcoming satellite launches. Although satellite-based soil moisture estimates have been globally available since the early 1990s, the satellite signal used to derive soil moisture estimates, has yet to be fully understood. In this thesis the interrelation between vegetation water and satellitebased soil moisture estimates is investigated for West Africa. Based on observations and a series of regional models the link between vegetation and satellite signal was hypothesized and tested. New methodologies for ground observations of soil moisture and vegetation water were developed, which provide the means to design experiments for calibration and validation of upcoming soil moisture satellites.","soil moisture; vegetation water; hydrology; remote sensing; West Africa","en","doctoral thesis","Zentrum für Entwicklungsforschung (ZEF)","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:b92f2beb-5dac-47c8-84ab-f5e681c8081c","http://resolver.tudelft.nl/uuid:b92f2beb-5dac-47c8-84ab-f5e681c8081c","Improving 2D change detection by using available 3D data","Van der Sande, C.J.; Zanoni, M.; Gorte, B.G.H.","","2008","Change detection with very high resolution imagery is difficult, because 3D objects as buildings appear differently in 2D imagery due to varying viewing angles and sun positions. This research proposes a method to improve change detection by using simple 3D models of buildings. Buildings have been modelled as flat roof or gable roof buildings. By knowing the position of the sun, the location of the shadow of a building is calculated. The location of the relief displacements is calculated using information on the position of the sensor. By introducing the projected shadow, relief displacement and roof in the automatic change detection process more reliable change signals are produced. An object-oriented approach for change detection is developed using segmentation techniques to create homogeneous segments from pixels. The method compares the object map t0 with the image t1. Information is gathered on how each object represents in the image t1 and at t0, by using the information of the image t0. In the case of shadow parts histogram stretched imagery are used. For the change detection on the roof, the roof segments are reprojected on top of each other to compare them. This method resulted in more reliable change detection results and increased the detection rate to 72% for changes to buildings.","remote sensing; change detection; updating; segmentation; 3D; object oriented","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:719c6058-5e69-4b5d-8646-9070394958ab","http://resolver.tudelft.nl/uuid:719c6058-5e69-4b5d-8646-9070394958ab","Observation of storm rainfall for flash-flood forecasting Volume 2 - Satellite structured algorithm system (SAS)","Delrieu, G.","TU Braunschweig","2008","This report summarizes the work done by the meteorological team of the TU Dresden within the FLOODsite Task 15 Radar and satellite observation of storm rainfall. The aim of this Task was the development of a radar and satellite Structured Algorithm System (SAS) for quantitative precipitation estimation (QPE) at the space and timescales of interest for flash-flood analysis and prediction. Thereby, the part of the TU Dresden was to develop a satellite based SAS for detecting extreme storm rainfall by using highly resolved geostationary satellite data (Meteosat-6, Meteosat-8). This has been done by building up a twofolded SAS, one part based on Meteosat-6 Rapid Scan data (M6/RS-SAS) and the second part based on Meteosat-8 data (MSG-SAS). Both parts include several rainfall estimation techniques. Three heavy precipitation events in orographic distinct and consequently flash flood prone regions (Alto Adige, Cévennes-Vivarais, Saxony) have been examined by applying these techniques with regard to the possibilities of detecting storm rainfalls by using satellite data. For validation and as a reference radar data of the co-operation partners INPG (Institut National Polytechnique de Grenoble) and UniPad (University of Padua) have been used. The Saxon event has been compared to radar data of the DWD (Deutscher Wetterdienst). To correct the estimated rain rates concerning the orographic situation, the wind and moisture conditions and the cloud growth rate additional data like MPEF products and radiosondes were included in the M6/RS-SAS. The rain rates resulting from the MSG-SAS were corrected in respect of the moisture conditions of the environment and the growing or decaying of the raining clouds.","Flash flood; Remote sensing; Satellite observation; Data processing","en","report","INPG Grenoble","","","","","","","","","","","","Floodsite",""
"uuid:9f12fd88-1ef3-4120-84ea-62fb4741aedc","http://resolver.tudelft.nl/uuid:9f12fd88-1ef3-4120-84ea-62fb4741aedc","Global soil moisture patterns observed by space borne microwave radiometers and scatterometers","Jeu, Richard A.M. (Vrije Universiteit Amsterdam); Wagner, W. (Technische Universität Wien); Holmes, T. R.H. (Vrije Universiteit Amsterdam); Dolman, A. J. (Vrije Universiteit Amsterdam); van de Giesen, N.C. (TU Delft Water Resources); Friesen, J (TU Delft Water Resources)","","2008","Within the scope of the upcoming launch of a new water related satellite mission (SMOS) a global evaluation study was performed on two available global soil moisture products. ERS scatterometer surface wetness data was compared to AMSR-E soil moisture data. This study pointed out a strong similarity between both products in sparse to moderate vegetated regions with an average correlation coefficient of 0.83. Low correlations were found in densely vegetated areas and deserts. The low values in the vegetated regions can be explained by the limited soil moisture retrieval capabilities over dense vegetation covers. Soil emission is attenuated by the canopy and tends to saturate the microwave signal with increasing vegetation density, resulting in a decreased sensor sensitivity to soil moisture variations. It is expected that the new low frequency satellite mission (SMOS) will obtain soil moisture products with a higher quality in these regions. The low correlations in the desert regions are likely due to volume scattering or to the dielectric dynamics within the soil. The volume scattering in dry soils causes a higher backscatter under very dry conditions than under conditions when the sub-surface soil layers are somewhat wet. In addition, at low moisture levels the dielectric constant has a reduced sensitivity in response to changes in the soil moisture content. At a global scale the spatial correspondence of both products is high and both products clearly distinguish similar regions with high seasonal and inter annual variations. Based on the global analyses we concluded that the quality of both products was comparable and in the sparse to moderate vegetated regions both products may be beneficial for large scale validation of SMOS soil moisture. Some limitations of the studied products are different, pointing to significant potential for combining both products into one superior soil moisture data set.","Global; Hydrology; Remote sensing; Satellites; SMOS; Soil moisture","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:4670da60-581e-4f6b-91b9-e2b563ac12fb","http://resolver.tudelft.nl/uuid:4670da60-581e-4f6b-91b9-e2b563ac12fb","Project plan, baseline silt PMR","Blaas, M.; Villars, M.T.; Tatman, S.","","2006","","remote sensing; remote sensing; data-analyse; data analysis; monitoring; monitoring; zwevende stoffen; suspended matter; kusten; coasts; Nederland","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:d71bf234-d464-4d6c-a93f-0385e2de4d4f","http://resolver.tudelft.nl/uuid:d71bf234-d464-4d6c-a93f-0385e2de4d4f","Radar turbulence detection: Statistical synthesis and experimental check of adaptive algorithms","Yanovsky, F.J.; Prokopenko, I.G.; Ligthart, L.P.","","2006","","radar; turbulence detection; adaptive algorithm; statistical synthesis; remote sensing of atmosphere","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Microwave Technology and Systems for Radar","","","",""
"uuid:9f11f2ef-2db4-4583-a763-aee88e06ee3b","http://resolver.tudelft.nl/uuid:9f11f2ef-2db4-4583-a763-aee88e06ee3b","Displacement parameter estimation using permanent scatterer interferometry","Kampes, B.M.","Klees, R. (promotor); Hanssen, R.F. (promotor)","2005","","remote sensing; radar interferometry; surface displacement; permanent scatterers","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:eb2560c9-2451-4de6-9897-1cb633dad911","http://resolver.tudelft.nl/uuid:eb2560c9-2451-4de6-9897-1cb633dad911","Nearshore subtidal bathymetry from time-exposure video images","Aarninkhof, S.G.J.; Ruessink, B.G.; Roelvink, J.A.","","2005","Time-averaged (over many wave periods) nearshore video observations show the process of wave breaking as one or more white alongshore bands of high intensity. Across a known depth profile, similar bands of dissipation can be predicted with a model describing the time-averaged cross-shore evolution of organized wave and roller energy. This close correspondence between observed and modeled dissipation proxies is used to develop a new remote sensing technique, termed Subtidal Beach Mapper (SBM), to estimate nearshore bathymetry. SBM operates on a time series of cross-shore intensity profiles to resolve the pattern in depth change on a morphological timescale (including overall gain or loss of sediment) rather than to focus on the particular change induced by a single intensity profile. From each intensity profile, the breaking-induced component is isolated by removing the contribution of background illumination and persistent foam. The depth profile is updated based on a comparison between this video-derived dissipation proxy and a cross-shore profile of the dissipation of the roller energy. This updating is implemented through time-dependent mass balance equations for the seabed and a buffer layer above the bed. SBM was tested using 1 year of hourly video data collected at Egmond aan Zee, Netherlands. The dominant morphological changes observed from ground truth data were reproduced reasonably well, including the shoreward migration of the outer bar and the net sediment gain in the profile. Root-mean square differences between surveyed and SBM derived depth after 1 year of video-based depth updating with an average of about 70 intensity profiles per month were smallest (~0.2 m) on the inner bar and largest (~0.6 m) in the outer bar trough, with a profile average value of about 0.4 m. Despite the many processes included in SBM, the implementation of a heuristic scaling function in the mass balance equations to spatially adjust morphological growth rates was essential to these results, in particular near the shoreline, where otherwise the profile is prone to an unrealistic deepening.","monitoring; nearshore bathymetry; remote sensing","en","journal article","American Geophysical Union","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:ca6503fb-cc2a-4cc6-ae12-78a9479952ea","http://resolver.tudelft.nl/uuid:ca6503fb-cc2a-4cc6-ae12-78a9479952ea","Bed variability in the surf zone at the storm- and seasonal time scale, mapped by Argus-video techniques: Preliminary results using the SBM-2DH model","Wijnberg, K.M.; Roelvink, J.A.; Aarninkhof, S.G.J.","","2004","","remote sensing; remote sensing; zeebodemonderzoek; seabed survey","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:029b0db7-b055-488c-a1ae-8dde5fee3a7e","http://resolver.tudelft.nl/uuid:029b0db7-b055-488c-a1ae-8dde5fee3a7e","Developing web-based multi-dimensional GIS; Conceptual framework","Rahman, A.A.; Zlatanova, S.; Pilouk, M.","","2003","","Urban sprawl; heuristic model; urban pattern recognition; GIS and remote sensing","en","conference paper","","","","","","","","","","","","","",""
"uuid:78bf20c8-aa8f-4464-a6f4-5572e28e54e9","http://resolver.tudelft.nl/uuid:78bf20c8-aa8f-4464-a6f4-5572e28e54e9","Contrast enhancement for depolarizing radar targets","Moisseev, D.N.","Ligthart, L.P. (promotor)","2002","","Radar; remote sensing; radar polarimetry; clutter suppression; target enhancement; doppler processing; atmospheric radar","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:a83859d5-c034-427e-b6a9-114c4b008d19","http://resolver.tudelft.nl/uuid:a83859d5-c034-427e-b6a9-114c4b008d19","Radar interferometry: Data interpretation and error analysis","Hanssen, R.F.","Klees, R. (promotor); Hartl, Ph. (promotor)","2001","","Remote sensing; radar; SAR; geodesy; error analysis; boundary-layer meteorology","en","doctoral thesis","","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:307ea66e-8b1f-4187-bd3c-b8356f476482","http://resolver.tudelft.nl/uuid:307ea66e-8b1f-4187-bd3c-b8356f476482","RESTWES Ecology: Use of remote sensing for classification of intertidal areas and preliminary ecological assessment of the disposal of tunnel boring material in the Western Scheldt","Baptist, M.J.","","1999","","remote sensing; remote sensing; ecologisch onderzoek; ecological research; sedimenten; sediments; Westerschelde","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:4051efe9-bf6b-42e8-9c57-355a6e2434dc","http://resolver.tudelft.nl/uuid:4051efe9-bf6b-42e8-9c57-355a6e2434dc","Remote sensing van algenbloeien in het IJsselmeer: Fase 1","Boderie, P.M.A.","","1999","","algen; algae; remote sensing; remote sensing; meetsystemen; monitoring systems; IJsselmeer","nl","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:6202e504-e527-4050-9656-d895505488ba","http://resolver.tudelft.nl/uuid:6202e504-e527-4050-9656-d895505488ba","RESTWES: REmote Sensing as a Tool for integrated monitoring of the WEstern Scheldt","Villars, M.T.; Vos, R.J.","","1999","","waterkwaliteitsmodellen; water quality models; remote sensing; remote sensing; Westerschelde","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:4b55a197-88bb-43fe-99a6-50ba56a58514","http://resolver.tudelft.nl/uuid:4b55a197-88bb-43fe-99a6-50ba56a58514","El Niño and satellite altimetry: Observation of large-scale waves on the Pacific Ocean","Brink, Wilbert","Schrama, E.O. (mentor); Klees, R. (mentor)","1999","De meest recente El Niño, die van 1997-98, was een van de hevigste gedetecteerde ooit en beïnvloedde het weer op globale schaal. In Zuid-Amerika waren de gevolgen bijna niet te overzien. Hevige regenbuien veroorzaakten onder meer modderstromen, die duizenden huizen vernielde, honderden bruggen en het leven kostte aan maar liefst 2100 mensen. Sinds een paar jaar weet men meer over het ontstaan van El Niño. Eens in de 3 tot 7 jaar, draaien de passaatwinden om naar het oosten en zorgen ervoor wat warm oppervlaktewater naar de kust van Zuid-Amerika wordt geblazen. Als een zogenaamde Kelvingolf beweegt dit water langs de evenaar naar het oosten. Daar aangekomen kunnen Kelvin golven omgebogen worden naar het noorden en het zuiden, om op hogere breedten westwaartse golven te creëren. Deze Rossby-golven bewegen met een breedteafhankelijke snelheid. Altimetrie-satellieten als TOPEX/Poseidon en ERS-2 kunnen relatieve zeehoogten meten met een precisie van enkele centimeters en zijn daarom uitermate geschikt om Kelvin en Rossby golven te visualiseren. Eerst moeten er nog wel enkele atmosferische en instrumentele correcties gedaan worden en moet er gecorrigeerd worden voor de geoïdehoogte en het tij. Metingen worden in een bepaalde baan verricht, die voor beide satellieten overigens nogal verschilt, zodat eigenlijk maar naar een kleine gedeelte van het zeeoppervlak echt gemeten wordt. Er moet dus geïnterpoleerd worden, waarvoor in deze scriptie een methode wordt voorgedragen die gebruikt maakt van variogrammen. Een zoek-radius van 4º met daarin een exponentiele gewichtsfunctie blijkt geschikt te zijn voor de ruimtelijke interpolatie. De gewichten van metingen op verschillende tijdstippen zijn gelijk. Met deze interpolatiemethoden kunnen zeehoogte-kaarten gemaakt worden, met rastercellen van 1º bij 1º. Het gemiddelde zeeniveau kan nog van de zeehoogten afgetrokken worden, omdat hier alleen de temporele verschillen van de zeetopografie interessant zijn. Dit heeft als bijkomend voordeel dat de relatief onbekende geoïde geëlimineerd wordt. Door de verschillende zeehoogtekaarten te combineren, kunnen er tijdlengtediagrammen gemaakt worden. Hierin zijn de Kelvin en Rossby golven te zien als evenwijdige lijnen. De helling van zo’n lijn is een maat voor de snelheid van de betreffende golf. Klimatologische verschijnselen hebben vaak een jaarlijks effect op de zeetopografie, wat weer storend kan werken op de lengte-structuren in de tijd-lengtediagrammen. Deze jaarlijkse trend is daarom geschat, door een sinus-functie met een periode van een jaar te fitten op de zeehoogte-data. De amplitude van de jaarlijkse cyclus is in sommige gebieden meer dan 10 cm. Radon-transformaties zijn een handige gereedschap om de helling – en dus de snelheid -van de lengte-structuren in de tijd-lengtediagrammen te detecteren. Het is gebaseerd op het integreren van lijnen met alle mogelijke posities en hellingen die er zijn, wat in het geval van een enkele lijn leidt tot een maximum in het Radon domein. The gevonden snelheden van de Kelvin golven komen goed overeen met theorieën, de Rossby-golfsnelheden zijn duidelijk te hoog. Een aanpassing van de theorieën die het meest waarschijnlijk is, is het feit dat er een soort gemiddelde stroming, die westwaarts gericht is, de Rossby-golven iets versnelt. Ook blijkt zeebodemtopografie – en met name onderzeese ruggen - de Rossby-golven te kunnen versterken en versnellen. Er is geen duidelijk verschil tussen TOPEX/Poseidon snelheden of ERS-2 snelheden, hoewel ERS-2 wel iets meer ruis laat zien in de tijd-lengtediagrammen. Door de tijd-lengtediagrammen te combineren zijn reflecties van equatoriale Kelvin en van Rossby golven waar te nemen. Kelvin golven wekken bijna altijd Rossby golven op in het oosten van de Pacific, maar ook vice versa in het westen. De grootschalige golven op de oceaan lijken daarom in een gekoppeld systeem te zitten, dat gecombineerd met winddraaiingen en – uitbarstingen een grote oorzaak van El Niño kan zijn.","TOPEX/Poseidon, ERS-2, El Niño, remote sensing","en","master thesis","","","","","","","","","Civil Engineering and Geosciences","Physical, Geometrical and Space Geodesy","","Applied Earth Sciences","",""
"uuid:26fe1f23-7ad3-4e09-ae66-de4018aea394","http://resolver.tudelft.nl/uuid:26fe1f23-7ad3-4e09-ae66-de4018aea394","Validation of a 3D temperature model for the North Sea with in-situ data and remote sensing data","Vos, R.J.; Goede, E.D. de; Uittenbogaard, R.E.","","1999","","temperatuurmeting; temperature measurement; zeewatertemperatuur; seawater temperature; remote sensing; remote sensing; North Sea","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:55d71a97-0e86-43ff-a974-04b6ee5392e4","http://resolver.tudelft.nl/uuid:55d71a97-0e86-43ff-a974-04b6ee5392e4","Drijflaagmodule DBS","Bokhorst, M.; Vonk, M.","","1997","","fytoplankton; phytoplankton; ecologische modellen; ecological models; remote sensing; remote sensing; Markermeer; IJsselmeer","nl","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:eb770e00-4695-487f-a0fa-31a1cb4eb9af","http://resolver.tudelft.nl/uuid:eb770e00-4695-487f-a0fa-31a1cb4eb9af","Meetstrategie 2000+: Integratie van remote sensing, in-situ waarnemingen en modelberekeningen van zwevend stof in de Nederlandse kustzone","Boon, J.G.; Baart, A.C.","","1996","","zwevende stoffen; suspended matter; remote sensing; remote sensing","nl","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:e865c710-bde5-4911-b176-8e21cb483d5a","http://resolver.tudelft.nl/uuid:e865c710-bde5-4911-b176-8e21cb483d5a","Architectures for Real-Time On-Board Synthetic Aperture Radar Processing","Bierens, L.H.J.","Dewilde, P.M. (promotor)","1995","","synthetic aperture radar; remote sensing; real-time processing","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:a038d438-d524-48c4-a7e2-265c344f881c","http://resolver.tudelft.nl/uuid:a038d438-d524-48c4-a7e2-265c344f881c","Efficiency improvement of bathymetry assessments using ERS-1 SAR imagery and ship's observations","Calkoen, C.J.; Wensink, G.J.","","1994","","Waddenzee; remote sensing; remote sensing; dieptemeting; depth measurement","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:b60b6760-62d1-414c-9d7f-60004f243282","http://resolver.tudelft.nl/uuid:b60b6760-62d1-414c-9d7f-60004f243282","Optical remote sensing of water quality parameters: Interpretation of reflectance spectra","Krijgsman, J.","Donze, M. (promotor)","1994","","Optical remote sensing; water quality parameters; reflectance","en","doctoral thesis","Delft University Press","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:e4f0a83d-ecf7-4f84-b25b-05bf66e8a714","http://resolver.tudelft.nl/uuid:e4f0a83d-ecf7-4f84-b25b-05bf66e8a714","Ground-based remote sensing of precipitation using a multi-polarized FM-CW Doppler radar","Russchenberg, H.W.J.","Ligthart, L.P. (promotor)","1992","","remote sensing; weather radar","en","doctoral thesis","Delft University Press","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:e5ba9159-429c-4631-9362-70e43d7911cf","http://resolver.tudelft.nl/uuid:e5ba9159-429c-4631-9362-70e43d7911cf","System design for ARTEMIS environmental monitoring","van Ingen Schenau, H.A.; Spaa, J.","","1992","This paper describes aspects of system design applied to the ARTEMIS environmental monitoring system of the Food and Agriculture Organization (FAO) of the United Nations. The design aspects are derived from characteristics of the monitoring function and are based on methods of rainfall and vegetation monitoring from satellite observations which are widely accepted for the user community. The satellites which meet the requirements for large scale monitoring purposes are the METEOSAT geostationary and NOAA polar-orbiting satellites. The thematic data processing is based on the method of ten-day cumulation of METEOSAT IR data for rainfall estimation and the method of ten-day composition of NOAA VIS and NIR data to determine the vegetation index. All processed images and maps are stored in an image database to build a long term archive. The information is used in the FAO monitoring programmes and in regional and national institutes in Africa.","Africa; Data acquisition; Environmental monitoring; Information systems; Meteosat satellite; Precipitation (meteorology); Remote sensing; Data bases; Drought; Early warning systems; Locusts; NCAA satellites; Real time operation; Satellite imagery; Soil moisture; Thematic mapping; Vegetative index; Weather satellites","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:60d46bc8-3bef-40d8-9dc7-df807591286a","http://resolver.tudelft.nl/uuid:60d46bc8-3bef-40d8-9dc7-df807591286a","Reconstruction of current profiles from HF radar surface current measurements by inverse modeling","Valk, C.F. de","","1991","","remote sensing; remote sensing; stroommeting; current measurement; radar; radar","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:e6c0fa55-ac6b-4805-aa6f-6945d2c5d49f","http://resolver.tudelft.nl/uuid:e6c0fa55-ac6b-4805-aa6f-6945d2c5d49f","Remote sensing en landmeetkunde","Looyen, W.J.","","1989","Working with Remote Sensing data can be generalized into four categories: - registration - processing - interpretation - presentation. A short overview of these four categories will be given. Emphasis will be put on the Dutch airborne multichannel pushbroom scanner CAESAR showing specific geodetic points of interest in working with Remote Sensing data.","remote sensing; classifying; imaging techniques; image processing; geometric rectification (imagery); multispectral band scanners; photomapping; aerial photography; satellite imagery","nl","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:cb768a89-92f7-45d9-abbf-3eb46f1d17a7","http://resolver.tudelft.nl/uuid:cb768a89-92f7-45d9-abbf-3eb46f1d17a7","Sea wave information from bathymetric LIDAR: One-dimensional approach","Calkoen, C.","","1989","","remote sensing; remote sensing; zeebodem; seabed","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:b67698ba-53bd-4597-b890-805b64c80657","http://resolver.tudelft.nl/uuid:b67698ba-53bd-4597-b890-805b64c80657","Bathymetry from landsat-TM images","Hesselmans, G.H.F.M.","","1989","","remote sensing; remote sensing; dieptemeting; depth measurement","en","report","Deltares (WL)","","","","","","","","","","","","",""
"uuid:054405f5-bd5b-45ea-b7f5-245c7d2aaeff","http://resolver.tudelft.nl/uuid:054405f5-bd5b-45ea-b7f5-245c7d2aaeff","CAESAR, a CCD airborne experimental scanner for applications in remote sensing radiometric and geometric calibration","Looyen, W.J.; van Swol, R.W.","","1989","Within the framework of the National Remote Sensing Programme, an airborne push-broom scanner was developed in The Netherlands by the National Aerospace Laboratory NLR and the Institute for Applied Physics TNO-TH (TPD). With the development of this scanner, named CAESAR, two objectives were fulfilled: technical knowledge about CCD detectors and practical experience with their application in remote sensing were gained and an important research tool was made available to remote sensing scientists. CAESAR was designed to make land and sea(water) observations in up to nine different wavelength bands. The application of CCD arrays in CAESAR required radiometric calibration of all individual CCD elements in order to meet the important user requirements on the minimum detectable ground reflectance variation. Since CAESAR is an airborne scanner geometric corrections are required as well, to compensate for image distortions due to aircraft motions. Both radiometric and geometric corrections are applied during the preprocessing of the data. Results of performance tests show that the design goals were met and that The Netherlands can offer to the remote sensing community an advanced airborne scanner for land and marine applications.","airborne equipment; remote sensing; push-broom sensor mode; multispectral bandscanners; radiometric correction; geometric accuracy; performance tests; user requirements","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:1a26c525-93dd-4d45-aa5f-c80fa1e45a33","http://resolver.tudelft.nl/uuid:1a26c525-93dd-4d45-aa5f-c80fa1e45a33","Updating land-use information on topographic maps using satellite imagery : combining the advantages of two accessible sources of geographic information","van der Laan, F.B.; Meijer, P.G.","","1988","This paper examines the possibilities of using Landsat Thematic Mapper images for updating land-use information on topographic maps. Information obtained from satellite images can be kept up-todate and a large number of classes can be distinguished. However, the quality of the information still leaves much to be desired, with a reliability of no more than 40 - 90 %. By using digitized landuse information from a topographic map as a source of contest information the reliability could be improved considerably. The method permitted the Identification of a large number of additional classes and provided quantitative insight into the dynamics of landscap change. Verification using 1:18,000 scale aerial photographs and field data showed the results to have a reliability of over 95 %. It can be expected that whereever topographic maps permit the extraction of land-use information in a similar way as described in this paper, remote sensing information will meet operational accuracy requirements for many fields of application e.g. physical planning, map udating, land-use planning etc. Paper presented at the IGARSS'88 conference ""Remote Sensing - moving towards the 21st century"" in Edinburgh, Scotland, 12-16 September 1988","remote sensing; updating; topographic map; reliability; land-use","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:e7a04c07-0b00-4320-8264-f93a28e33ce9","http://resolver.tudelft.nl/uuid:e7a04c07-0b00-4320-8264-f93a28e33ce9","Numerical accuracy of a two-stream radiative transfer model from comparison with an N-stream model","Verhoef, W.","","1988","In the past, a relatively simple radiative transfer model, based on scattering and extinction of two semi-isotropic diffuse fluxes and two direct fluxes (solar beam and radiance in the viewing direction), has been applied to vegetation canopies and to the atmosphere. This model takes little computing power, but its numerical accuracy had not yet been established. The present paper introduces a refined N-stream model, with vectorized Kubelka-Munk equations and with the two additional direct fluxes. It was implemented for N equal to 72, which can be assumed accurate enough for remote sensing applications. Comparison calculations were carried out for the scattering of light by atmospheric haze, which is a medium that is most difficult to model, in order to evaluate the accuracy of the simple model under a number of simulated circumstances, given by optical thickness and observation geometry. The results are used to assess the limits to the applicability of the simple model. Paper presented at the 4th International Colloquium on Spectral Signatures of Objects in Remote Sensing, Aussois, France, 18-22 Jan. 1988","radiative transfer modelling; simulation; accuracy; atmosphere,; scattering; remote sensing; aeroso","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:405bc6f2-b552-41d3-919a-e1d11144dd1b","http://resolver.tudelft.nl/uuid:405bc6f2-b552-41d3-919a-e1d11144dd1b","CADISS: a multi-processor system for image compression/decompression on board scientific satellites","Roefs, H.F.A.; Monkel, A.","","1987","Project CADISS has produced an elegant breadboard of a system for compression (and -if required- decompression) of signals generated by imaging sensors on-board scientific satellites. The performance, specifications and physical characteristics of CADISS are the result of trade-offs on function (algorithms), technology, through-put speed and cost. CADISS is a low-power, (micro) programmable multi-processor prototype system with interfaces to a Remote Terminal Unit (for downloading of software), to image data generating instruments and to the on-board formatter. This report describes the concept of CADISS, its algorithms, its technology and the test results. It should be noted that the design was frozen mid 1983, using technology which was state-of-the-art at that time.","Onboard data processing; Remote sensing; Data compression; Data reduction; Algorithms; Coding; Image processing; Image reconstruction; Satellite imagery; Multiprocessing (computers); Breadboard models","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:58d123d5-bb0b-4370-a20a-d2c5cfcf3369","http://resolver.tudelft.nl/uuid:58d123d5-bb0b-4370-a20a-d2c5cfcf3369","Studie naar de opzet van een nationaal ERS-1 datacentrum - Phase-A/B study of a national ERS-1 data centre","van Swol, R.W.","","1987","Within the framework of the National Remote Sensing Programme and under contract with the Netherlands Remote Sensing Board (BCRS), the National Aerospace Laboratory NLR has carried out a Phase-A/B study of a national ERS-1 data and information centre. The first European Remote Sensing Satellite (ERS-1) is due to be launched by the European Space Agency (ESA) in 1990. In this study an investigation was made of the requirements with respect to the reception and the dissemination of the ERS-1 data products in the Netherlands. An inventory was made of the ERS-1 data products, of the dissemination methods to be used by ESA and of the Dutch users. It appears that real-time application of the Low Bit Rate data in regional forecasting models forms the most important operational application in the Netherlands. Therefore, it is recommended in this report to receive the real-time data by the Dutch meteorological office KNMI, which is the principle user of these data. Furthermore, it is recommended that the NLR, as the National Point of Contact (NPOC) for Landsat data and as the official SPOT data distributor, also takes care of the handling of requests for and the off-line distribution of ERS-1 data products.","Satellite; ERS-1 (ESA satellite); Remote sensing; Data acquisition; Real time operation; User requirement; Information dissemination; Earth resources information system; Ground stations; Netherlands; Oceanographic parameters; Meteorological parameters","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:c5d841fc-bdee-459d-863f-092c2b0f3287","http://resolver.tudelft.nl/uuid:c5d841fc-bdee-459d-863f-092c2b0f3287","A modular and versatile acquisition, recording and preprocessing system for airborne remote sensing","Pouwels, H.; Aartman, L.J.","","1986","The National Aerospace Laboratory ""NLR"" is the operator of an aircraft which can be equipped with either a SLAK, a multl spectral scanner or a TVbased scanner. The airborne recording equipment la designed to accommodate these various sensors. The general airborne system setup is: the sensor, a dedicated digitizing unit and an Interface to a High Density Digital Tape recorder. Aircraft parameters like position, attitude and time are recorded on the same tape. Flight tapes are replayed on existing equipment as used for PCM encoded telemetry data; only a High Bit Rate Decoding unit is added. Raw remote sensing data and flight data are transfered to computer tapes. The software system PARES (Preprocessing Airborne Remote Sensing) performs radiometric and geometric corrections for aircraft motion and for sensor characteristics,","airborne remote sensing; digital instrumentation; data handling; preprocessing","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:8549f2f0-ed1a-44f6-9bfa-f2c5b6369547","http://resolver.tudelft.nl/uuid:8549f2f0-ed1a-44f6-9bfa-f2c5b6369547","Crop identification with microwaves (SLAR-data of 1985)","Uenk, D.; Binnenkade, P.","","1986","Microwaves (i.e. X-band SLAR) have been used in The Netherlands for many years within ROVE to identify agricultural crops. This report deals with data acquisition, preprocessing and classification of agricultural crops in The Netherlands using the Dutch Digital SLAR. With internal and external calibration of the instrument satisfactory results have been achieved in identifying the main agricultural crops in The Netherlands (wheat, sugarbeets and potatoes)","Crop identification; Remote sensing; Airborne equipment; Side looking radar; Data acquisition; Classifications; Preprocessing; Farm crops; Netherlands","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:b97f47f5-28e7-4055-a8b6-e27e01ea09e6","http://resolver.tudelft.nl/uuid:b97f47f5-28e7-4055-a8b6-e27e01ea09e6","Test results of image segmentation algorithm on the RESEDA system (in Dutch)","Nooren, G.J.L.; Hoekman, D.H.","","1986","The image segmentation algorithm has been tested by means of imagery of agricultural areas and forests acquired by airborne SLAR as well as Seasat SAR. The accuracy was determined for segmentation without any postprocessing and with emphasis on estimation of area and field average. Besides, the (positive) influence of segmentation on classification results was investigated.","Radar remote sensing; Segmentation; Classification","nl","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:ea447e35-f356-49b3-832f-973f0f4d611f","http://resolver.tudelft.nl/uuid:ea447e35-f356-49b3-832f-973f0f4d611f","A scene radiation model based on four-stream radiative transfer theory","Verhoef, W.","","1985","A simple analytical four-stream radiative transfer model based on Suits's differential equations is applied to the atmosphere-earth system in order to investigate the effects of the atmosphere and the view angle on remotely sensed multispectral radiance data from vegetation canopies. This scene radiation model is composed of two atmospheric layers and one vegetation layer resting on a Lambertian soil, which are combined by the Adding method. Input data for the model are Elterman's data on atmospheric optical depths, Deirmendjian's phase functions for atmospheric haze, visibility, directions of the sun and of observation, and canopy parameters of the SAIL vegetation reflectance model, such as LAI and the leaf angle distribution. Paper presented at the '3rd International Colloquium on Spectral Signatures of Objects in Remote Sensing, Les Arcs, France, 16-20 Dec. 1985.","radiative transfer modelling; earth-atmosphere system; image generation; simulation; Canopy reflectance; radiance; multispectral remote sensing","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:2488f2e8-e421-4246-bc4e-ccd1e88399ee","http://resolver.tudelft.nl/uuid:2488f2e8-e421-4246-bc4e-ccd1e88399ee","Image quality criteria with emphasis on criteria for remote sensing imagery","van der Lubbe, J.C.A.","","1984","Image quality plays an important role on the various levels of image processing. However, until now it lacks a survey of methods for the evaluation of image quality. With a grant of the Netherlands Agency for Aerospace Programs (NIVR) a study was performed with respect to the quantification of image quality. Some results of this study are reflected in this report. This report is meant as a guide for the measurement of image quality in its various facets. In addition to already common approaches to image quality assessment also attention is paid to less often considered aspects of image quality like texture and edge quality.","image processing; remote sensing; edges; imaging techniques; multi spectral photography; accuracy; image analysis; quality; criteria; pattern classification; datacompression; distortion; entropy; coding; gray scales; textures","en","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:c1bf7cb5-5c20-42aa-930f-994c40cba842","http://resolver.tudelft.nl/uuid:c1bf7cb5-5c20-42aa-930f-994c40cba842","Contributions to remote sensing: Applications of thermal infrared","Brunsveld van Hulten, H.W.","Hoogeboom, P. (contributor); Jacobs, A.F.G. (contributor); Kraan, C. (contributor); De Loor, G.P. (contributor); Wartens, L. (contributor); Rijkswaterstaat","1984","A uniform, effective and equitable system of quality control for pavements has been applied to road-building projects in the Netherlands since 1968.The system has been developed in consultation between the public authorities and the con tractors' organizations. The system is characterized by a distinction between regular, daily production control by the contractor and limited retrospective acceptance control by the public authority based on random samples. Under the existing non-statistical system, samples (one per 2000 m2) are examined to determine the layer thicknesses, sand cement strength and density and bitumen content of the asphalt. When the quality does not meet the specified values, financial penalties are applied the level of which depends on the extent of the deviation from the set standards. In the light of experience with over 300 major projects, the system has now been developed into an almost entirely statistical method of control which is ready for practical introduction.","remote sensing; infrared; thermal mapping","en","report","Rijkswaterstaat","","","","","","","","","","","","",""
"uuid:aaa24f73-f377-4f14-ba85-22111b108626","http://resolver.tudelft.nl/uuid:aaa24f73-f377-4f14-ba85-22111b108626","Non-destructieve bepaling van gewaseigenschappen met behulp van multispectrale scanning","Bunnik, N.J.J.","","1977","The spectral distribution of radiation reflected by crops in the visible light region and the near infrared contains information concerning crop structure and the optical properties of the leaves and the bounding soil. Non-destructive determination on remote distance of crop properties by means of the measured spectral distribution of reflected radiation is feasible and produces useful information for agricultural management within a short time and over extended areas. A mathematical model, physically describing the reflectance by vegetation canopies, has been used to investigate information extracted from the reflectance spectrum uniquely related with crop properties of interest for agricultural applications. By means of an example and field measurements performed it is indicated how the soil cover percentage can be determined from MSS data. The complex relation between the reflectance spectrum and crop variables can be simplified drastically when the direction of incoming radiation and detection coincide and the crop is observed perpendicularly or under an oblique zenith angle of approximately 52°. Active conical scanning under 52° with a restricted number of wavelength bands can offer, besides operational advantages, useful data concerning the soil cover percentage, the total leaf area, leaf colour and the moisture conditions of the bounding soil. This is illustrated by means of model simulations.","remote sensing; multispectral band scanning; conical scanning; crop identification; spectral signatures; optical reflection; infrared reflection; reflectance; crop growth; foliage","nl","report","Nationaal Lucht- en Ruimtevaartlaboratorium","","","","","","Campus only","","","","","","",""
"uuid:1a9f5933-625b-43c5-842e-9599a8ce0690","http://resolver.tudelft.nl/uuid:1a9f5933-625b-43c5-842e-9599a8ce0690","Systems for automatic computation and plotting of position fixing patterns","Van der Schaaf, H.P.","Rijkswaterstaat","1972","In the past ten years there has been a growing tendency to use hyperbolic, circular and 'are of circle patterns for position fixing on water-covered areas. Rijkswaterstaat Communications No. 2 discusses the computations associated with the Decca pattern for the Netherlands Delta Project as one ofthe first examples ofthe use of electronic computers by the Survey Department of the 'Rijkswaterstaat'. The introduction of automatic platting equipment has now made it possible to reduce manual computing and platting work to an absolute minimum. Under the supervision of Prof. Dr. D. Eckhart, acting as our consultant on computerization problems, a complete software package has been developed for the computation and plotting of position fixing patterns. The systems on which this software is based are described in this issue of 'Communications'. In the simplest systems, the depiction of the earth's surface by a system of map projection is assumed to provide an undistorted representation, thus enabling plane hyperbolic, circular and are of circle patterns to be used. This mathematical model must, however, be refined if the inaccuracies inherent in the type of projection used are to be taken into account. The plane pattern, or alternatively the accompanying grid or graticule, may be modified for this purpose. Systems of this kind are described, not only with regard to the chart patterns but also with regard to the relationship between the chart and the transmitted patterns together with the calibration necessary to determine the pattern constants.","remote sensing; navigation; positioning systems","en","report","Rijkswaterstaat","","","","","","","","","","","","KWP-collection",""