ME
M.A. Eleveld
info
Please Note
<p>This page displays the records of the person named above and is not linked to a unique person identifier. This record may need to be merged to a profile.</p>
3 records found
1
Master thesis
(2020)
-
S. de Roda Husman, S.L.M. Lhermitte, F.J. Lopez Dekker, M.A. Eleveld, J.J. van der Sanden
Ice jam events can be devastating for the environment, human infrastructure, and local population. During breakup season, it is of great importance to be informed about the river ice cover condition in order to mitigate breakup flood risk. The Athabasca River near FortMcMurray, located in Alberta, is particularly prone to ice jam events and subsequent floodings. Satellite remote sensing techniques provide the necessary means to monitor the ice cover. Because of the wide availability most research and operational services for SAR river ice classification are based on single- or dual-polarized images. However, such imagery is limited in its ability to distinguish certain river ice types and open water states. The research presented examines how SAR polarimetry influences the detecting possibilities of specific ice types. Sentinel-1 (dual-polarization), RADARSAT-2 (quad-polarization) and RADARSAT Constellation Mission (compact-polarization) data were used to classify river ice during breakup. This study was about analysing a stretch of the Athabasca River which is prone to ice jam formation. First, SAR images from the 2018-2019 and 2019-2020 breakup were studied to find the temporal and spatial patterns of the radar backscatter. Next, sample areas with known ice stage (sheet ice, ice jam or open water) were selected. The sample areas of each ice stage were compared to assess the influence of SAR characteristics, as incidence angle and overpass time. In the last part of this study, a Random Forest classification was implemented in which intensity, texture and polarimetric features were used. Results show that classification accuracies increase with the inclusion of polarimetric decomposition features and GLCM mean texture features by enhancing between class separability and reducing the misclassification. Accuracies of 85.6% (Kappa = 0.78), 91.2% (Kappa = 0.87) and 91.0% (Kappa = 0.87) were obtained for Sentinel-1, RADARSAT-2 and RCM, respectively. The majority of the confusion between classes was due to similarities at backscatter signatures in very small incidence angles, mainly between open water and sheet ice under melting conditions. Also sheet ice early in the breakup season was confused with ice jams. To reduce the likelihood of misclassification, it is recommended to only use images with incidence angles higher than 30º and to include polarimetric and texture features in a classifier. Additional improvements can be achieved when using expert knowledge for tracking, since previous SAR images can provide added information when one understands the temporal patterns of river ice breakup. Further research should be directed at the development of an automatic classification approach that should be able to detect ice jams during the entire ice covered season. Having more knowledge about river ice breakup may help to eventually develop a river ice forecasting system, which may significantly reduce flood risk.
...
Ice jam events can be devastating for the environment, human infrastructure, and local population. During breakup season, it is of great importance to be informed about the river ice cover condition in order to mitigate breakup flood risk. The Athabasca River near FortMcMurray, located in Alberta, is particularly prone to ice jam events and subsequent floodings. Satellite remote sensing techniques provide the necessary means to monitor the ice cover. Because of the wide availability most research and operational services for SAR river ice classification are based on single- or dual-polarized images. However, such imagery is limited in its ability to distinguish certain river ice types and open water states. The research presented examines how SAR polarimetry influences the detecting possibilities of specific ice types. Sentinel-1 (dual-polarization), RADARSAT-2 (quad-polarization) and RADARSAT Constellation Mission (compact-polarization) data were used to classify river ice during breakup. This study was about analysing a stretch of the Athabasca River which is prone to ice jam formation. First, SAR images from the 2018-2019 and 2019-2020 breakup were studied to find the temporal and spatial patterns of the radar backscatter. Next, sample areas with known ice stage (sheet ice, ice jam or open water) were selected. The sample areas of each ice stage were compared to assess the influence of SAR characteristics, as incidence angle and overpass time. In the last part of this study, a Random Forest classification was implemented in which intensity, texture and polarimetric features were used. Results show that classification accuracies increase with the inclusion of polarimetric decomposition features and GLCM mean texture features by enhancing between class separability and reducing the misclassification. Accuracies of 85.6% (Kappa = 0.78), 91.2% (Kappa = 0.87) and 91.0% (Kappa = 0.87) were obtained for Sentinel-1, RADARSAT-2 and RCM, respectively. The majority of the confusion between classes was due to similarities at backscatter signatures in very small incidence angles, mainly between open water and sheet ice under melting conditions. Also sheet ice early in the breakup season was confused with ice jams. To reduce the likelihood of misclassification, it is recommended to only use images with incidence angles higher than 30º and to include polarimetric and texture features in a classifier. Additional improvements can be achieved when using expert knowledge for tracking, since previous SAR images can provide added information when one understands the temporal patterns of river ice breakup. Further research should be directed at the development of an automatic classification approach that should be able to detect ice jams during the entire ice covered season. Having more knowledge about river ice breakup may help to eventually develop a river ice forecasting system, which may significantly reduce flood risk.
Master thesis
(2019)
-
Kostas Vlachos, Paco Lopez Dekker, Ihor Smal, Marieke Eleveld, Martin Verlaan
Satellite altimetry is an important technology used to measure sea level with high spatial and temporal resolution. Sentinel-3, a Copernicus satellite mission, offers three types of variables captured simultaneously for the first time; sea level (SSH), sea surface temperature (SST) and ocean colour (OC) variables. Sea level is measured with SAR altimetry, a technique that considerably increases spatial resolution compared to other means of observation. Altimetry measures sea level across a line that coincides with the satellite ground track, whereas SST and OC are measured on a grid. What we lack are sea level observations in-between ground tracks that would better resolve meso-scale variability. This thesis is focused on two objectives, considering previous work that has indicated associations between those variables. The first objective was to investigate the correlations among SSH, SST and OC, while the second objective was to assess to what extent inter-track sea level can be estimated using SST and OC as predictors in machine learning algorithms. Daily Sentinel-3 data over a period of eleven months were pre-processed and brought into a form that allowed for computation of metrics such as auto- and cross-correlations in the along-track direction. The focus was on the spatial scales that would enable to detect meso-scale features, such as eddies. With respect to the inter-track sea level estimation two paths were followed. In the first path, Random Forest (RF) and Multilayer Perceptron (MLP) were applied using the complete 11-month dataset as input. Moreover, RF was applied on input data that belong to each separate day. In the second path, 1D Convolutional Neural Network (CNN) was used on the complete 11-month dataset, which inherently honors the spatial dependency of the variables in contrast to the first path. Generally, the correlations between the variables were found to exist in the meso-scale but were not always strong and they depend on several other factors, such as meteorological conditions, scales included in the analysis and techniques used. All three techniques -RF, MLP and 1D CNN- that were applied on the complete 11-month dataset gave poor results. On the contrary, when RF was applied on the per-day data gave promising results that are reliable mostly in the vicinity of the ground track, although they are not based on one single global model. The results from this project suggest that there must be more research on the correlation analysis of Sentinel-3 data. It can be improved by using additional or similar techniques, such as localized cross-correlation metrics on various spatial scales. With respect to the inter-track sea level estimation, far more investigation is needed. However, there are indications that a machine learning data-driven approach could potentially work to some extent. Sentinel-3 data will become more abundant in the next years which will assist data science algorithms such as CNNs which require huge datasets.
...
Satellite altimetry is an important technology used to measure sea level with high spatial and temporal resolution. Sentinel-3, a Copernicus satellite mission, offers three types of variables captured simultaneously for the first time; sea level (SSH), sea surface temperature (SST) and ocean colour (OC) variables. Sea level is measured with SAR altimetry, a technique that considerably increases spatial resolution compared to other means of observation. Altimetry measures sea level across a line that coincides with the satellite ground track, whereas SST and OC are measured on a grid. What we lack are sea level observations in-between ground tracks that would better resolve meso-scale variability. This thesis is focused on two objectives, considering previous work that has indicated associations between those variables. The first objective was to investigate the correlations among SSH, SST and OC, while the second objective was to assess to what extent inter-track sea level can be estimated using SST and OC as predictors in machine learning algorithms. Daily Sentinel-3 data over a period of eleven months were pre-processed and brought into a form that allowed for computation of metrics such as auto- and cross-correlations in the along-track direction. The focus was on the spatial scales that would enable to detect meso-scale features, such as eddies. With respect to the inter-track sea level estimation two paths were followed. In the first path, Random Forest (RF) and Multilayer Perceptron (MLP) were applied using the complete 11-month dataset as input. Moreover, RF was applied on input data that belong to each separate day. In the second path, 1D Convolutional Neural Network (CNN) was used on the complete 11-month dataset, which inherently honors the spatial dependency of the variables in contrast to the first path. Generally, the correlations between the variables were found to exist in the meso-scale but were not always strong and they depend on several other factors, such as meteorological conditions, scales included in the analysis and techniques used. All three techniques -RF, MLP and 1D CNN- that were applied on the complete 11-month dataset gave poor results. On the contrary, when RF was applied on the per-day data gave promising results that are reliable mostly in the vicinity of the ground track, although they are not based on one single global model. The results from this project suggest that there must be more research on the correlation analysis of Sentinel-3 data. It can be improved by using additional or similar techniques, such as localized cross-correlation metrics on various spatial scales. With respect to the inter-track sea level estimation, far more investigation is needed. However, there are indications that a machine learning data-driven approach could potentially work to some extent. Sentinel-3 data will become more abundant in the next years which will assist data science algorithms such as CNNs which require huge datasets.
Master thesis
(2019)
-
Reinoud de Klerk, Stefan Aarninkhof, Sierd de Vries, Marieke Eleveld, Marjan Duiveman, Joost den Bieman, Bart van Westen
The influence of beach buildings on coastal dune development is still largely unknown, and it could pose a risk to the functionalities coastal dunes provide. The objectives of this research are covered by the main research question: What is the influence of specific types of beach buildings on aeolian coastal dune development and what are suitable dune management measures? This study uses high resolution LiDAR elevation measurements taken with an UAV of two case areas in the Netherlands to investigate the influence of beach buildings on aeolian coastal dune development. Measurements are made of two stretches of beach located in Julianadorp and Sint Maartenszee, where various beach building types are present. Different dune regions are classified based on the presence of building types. The elevation data is discretized in grids that are placed adjacent to the dune foot along these classified regions. Elevation changes and cross-profile evolution of the dunes within these regions make it possible to consistently analyse differences in dune development with quantitative parameters.
...
The influence of beach buildings on coastal dune development is still largely unknown, and it could pose a risk to the functionalities coastal dunes provide. The objectives of this research are covered by the main research question: What is the influence of specific types of beach buildings on aeolian coastal dune development and what are suitable dune management measures? This study uses high resolution LiDAR elevation measurements taken with an UAV of two case areas in the Netherlands to investigate the influence of beach buildings on aeolian coastal dune development. Measurements are made of two stretches of beach located in Julianadorp and Sint Maartenszee, where various beach building types are present. Different dune regions are classified based on the presence of building types. The elevation data is discretized in grids that are placed adjacent to the dune foot along these classified regions. Elevation changes and cross-profile evolution of the dunes within these regions make it possible to consistently analyse differences in dune development with quantitative parameters.