Climate change has led to an increased frequency of extreme rainfall events, creating significant challenges for polder regions where water has to be pumped out actively. Tractor pumps stand out as a quick, flexible measure to improve polder discharge capacities. However, in extreme rainfall events, where the need for tractor pumps exceeds available supply, strategic decisions must be made on where to deploy them. This requires a data-driven methodology to support decision making. To achieve this, flood modelling, damage assessment and pump allocation optimization are combined in this study. The study aimed to create a framework that combines these in one integrated model and allocates a limited set of tractor pumps to the polders where they reduce total economic losses most. The study focused on the 18-20 June 2021 flood event, using 20 tractor pumps and 48 selected polders in Hoogheemraadschap Hollands Noorderkwartier. Polder flood damages were quantified through Depth Damage Curves (DDCs), incorporating terrain and land use data from the WaterSchadeSchatter. A two-stage Mixed Integer Linear Program was then formulated to determine optimal placement of tractor pumps, where the First-Stage selected polders and the Second-Stage assinged pumps. The model systematically evaluated all possible allocation options, identifying which placements minimized total damage.

Key findings were that DDCs are not suited for assessing the impact of tractor pumps on polders in linear programming models, as the relation between volume and water levels in a polder are nonlinear. Instead, Volume Damage Curves (VDCs) are more appropriate, as they are able to quantify damage per cubic meter, the variable that pumps directly influence. VDC derivatives were used to classify polders into three types: Type 1 (always relevant), Type 2 (tipping point dependent), and Type 3 (low priority). Of the 48 polders included in the study, 25 were classified as Type 3. Of these, only 2 received pumps, and in both cases the prevented damage was minimal. In contrast, Type 1 and tipping point exceeding Type 2 polders accounted for nearly all significant damage reduction. This suggests that Type 2 polders below their tipping point, and Type 3 polders can be used for polder deselection and as an alternative for the First-Stage model.

A shortcoming was that with the current VDC use, the maximum water volume is the primary driver of damage, as the flood duration is assumed fixed. For agricultural and infrastructural areas, flood duration strongly influences economic losses, suggesting that both the VDC construction and use in the optimization model must be altered to incorporate duration as an influencing variable. VDCs that do so require the direct damage term of every polder to be corrected for the flood duration. This can be done for specific polder increments, where each increment is multiplied with a duration factor. After every model run the accumulated duration for each increment should be stored and passed to the next run, allowing the model to account for ongoing flooding.

Modeling duration in linear programming greatly increases the number of variables and constraints. To keep the enlarged formulation solvable, the pump placement variable should be aggregated by counting pumps only per type and time step instead of individual pump tracking. This change removes the distinction between the First- and Second-Stage, rendering polder subset selection by the First-Stage infeasible. Instead, the polder classification types can be used for subset selection before the solver starts, so the enlarged single stage model still finishes in time for operational use.

To support real-time decisions, HHNK should develop a short horizon model that integrates improved VDCs, forecasted rainfall, current water levels converted to polder volumes, and current pump placements. As new data becomes available, the model should update pump allocation accordingly. The current optimisation model can serve as a starting point for this operational tool. ... Read more

Flood risk management is essential in water resource planning to reduce potential damages and losses in flood-prone areas. Traditional risk assessments often focus on monetary values and ignore equity, leading to unequal distribution of protective measures. The equity weighting method has been implemented in past studies, but at certain administrative levels, it may not capture the income heterogeneity within those areas. This research investigates how accounting for income heterogeneity within administrative areas affects equity-weighted risk and impact estimates and explores practical ways to implement this approach, given privacy-related data limitations.

The study focuses on Charleston County, South Carolina, using disaggregated methods at the household level to integrate detailed socioeconomic data into equity-weighted flood risk assessments. The methodology involves assuming an equal distribution of income within predefined brackets and optimizing upper and lower bounds for open income brackets. Additionally, a linear relationship is assumed between the structure value and household income, allowing for the spatial allocation of income within census block groups.

The results demonstrate that the disaggregated method identifies more vulnerable households and shows significant differences in equity-weighted damage (EWD) and equity-weighted expected annual damage (EWEAD) metrics compared to the aggregated method. These findings suggest that the disaggregated method provides useful evidence for considering the importance of taking into account income heterogeneity when assessing flood risks, particularly in areas with significant income inequality.

Sensitivity and uncertainty analyses indicate that the income distribution parameters show both low sensitivity and low uncertainty when using a fitted log-normal distribution, suggesting that this distribution is a good fit for the data and provides stable results. In contrast, in the spatial allocation of income with structural values, the analysis results show high sensitivity and significant uncertainty, which means small changes in structure values lead to substantial variations in equity weight estimates.

The study concludes with recommendations for stakeholders to adopt household-level analysis and incorporate equity weights in cost-benefit analyses. Future research should explore additional socioeconomic factors, develop dynamic risk assessment models, and apply the methodology to diverse geographic and economic contexts. ... Read more

Monitoring and modelling water systems and potential interventions help to manage water more effectively. However, due to defects and operational failures in sensors, the reliability of monitoring and modelling is affected by incomplete data. Because traditional statistical methods are often ineffective in infilling large and multivariate gaps, several machine learning (ML) techniques have been explored. However, a comprehensive overview of ML techniques and their performance across different methods and hydrologic regimes is missing. Therefore, this thesis project tackles the question: What ML approach(es) are most suitable for infilling gaps in hydrological time series in The Netherlands? 

This thesis evaluates ML models and their behaviour with different methods and hydrologic regimes. This study will help to understand the generalisability of the ML models, while also enabling improvements in (urban) water management. In this thesis, a multicriteria analysis (MCA) was used to assess a wide range of ML models. Next, during two case studies, a subset of these models were applied to infill gaps in groundwater, sewage water and surface water levels using the intra-station and inter-station methods. 
In the MCA, it was found that Support Vector Regressor (SVR), Random Forest (RF), Gradient Boosting Trees (GBT), Multilayer Perceptron (MLP), Self-Organising Map (SOM) and Long-Short Term Memory (LSTM) were sufficiently suitable. 
In the first case study, the use of these models with the intra-station approach led to mixed results for infilling small artificial gaps. Generally, acceptable MSE scores were achieved but poor NSE and KGE scores implied limited scalability. 
The second case study showed more promising results with the inter-station method on an artificial gap of seven months. This method proved to be more scalable as all metrics indicated acceptable performance.

In the end, it was concluded that both the RF and GBT models performed most robustly. The MLP and LSTM models showed great potential but suffered from inconsistency, potentially caused by too little training data. It was also found that the inter-station method proved more scalable as compared to the intra-station approach. Furthermore, it was found that success is dependent upon conditions of the hydrologic regime such as human intervention. ... Read more

The Province of South Holland is conducting a heritage project to explore the historical significance of barge canals and their future role in a changing climate. This thesis aims to address the water challenges posed by increased floods and droughts caused by climate change through the implementation of a water buffersystem. The buffer should allow the region to serve as a drainage during storms and retain water during droughts, considering the projected climate conditions in 2100. The study focuses on a large case study area, the heart of South Holland, which is enveloped by barge canals and divided into three water boards. A water balance model, calibrated using existing pump time series, is utilized to simulate water flows at the polder level. The model demonstrates sufficient accuracy for predicting larger spatial and seasonal scales within the jurisdiction of the water boards. Future conditions are simulated in the model by incorporating KNMI scenarios. However, the scenarios underestimate the occurrence of droughts, resulting in an underestimation of polder inlet and an overestimation of outlet. 
An above-average extreme climate change scenario is used to compensate for these biases. Combining the model output with long term statistical storm and drought forecasts, this leads to a more realistic buffer design capacity. If the reservoirs can be operated as prescribed, the primary hydrological purposes of the natural water buffers can complement each other. The first criterion consists of the buffering of the increased inequality of net inflow distribution throughout an average expected year, for which 20 million m³ with an additional top layer of 115 mm would be necessary. The second criterion entails the draining of the increase of intense precipitation events. 7.5 million m³ would be necessary to drain the extra precipitation of a 1000 year return period storm event. Thirdly, the buffers should be able to provide water, compensating for the aggravation of drought conditions. 34 million m³ should suffice to compensate for the aggravation of droughts with a return period of 2 years and longer. As the criteria are conditionally compatible, 34 million m³ is the net minimum required buffering capacity for the center of South Holland. 
The final optimal buffering strategy entails the realization of a large buffer in the Noordplaspolder, connecting the Rotte and the Hoogeveensche Vaart, and of a smaller buffer in Schieveen. It also requires the expansion of the water reservoirs in the Eendragtspolder and Berkel. The larger buffer will feature a deeper canal, permanently submerged, linking the Rotte and the Hoogeveensche Vaart, which in turn will connect to the nearby boezem water network. The Noordplaspolder and Eendragtspolder will buffer the area of the two water boards Rijnland and Schieland and the Krimpenerwaard that are inside the case study area, Schieveen and Berkel will buffer Delfland. The Schie and the Vliet will play important roles as water carriers between Delfland and its neighboring water boards and the Nieuwe Maas. This strategy not only addresses water management but also offers recreational, historical, and ecological opportunities. It revives the functions of old barge canals, the Vliet and the Schie, and restores the connection between the Rotte and the Hoogeveensche Vaart, adding to the solution's historical value. ... Read more

Water is essential for life on earth and is vital for numerous sectors of our society. Pressures arising from climate change, growing populations, and the shift towards clean energy accentuate the importance of effective water management. To make decisions about water resource allocation, hydraulic modeling studies have been undertaken on large African rivers. These studies employ global terrain models, utilize remotely sensed water surface elevation data, and often involve estimating river channel bathymetry. Typically, these models also require an estimation of the river channel bathymetry. However, observed bathymetry data is seldom available and crucial for the hydraulic model performance. It has resulted in a key challenge of modelling large rivers in this data-sparse context.
This research aims to model a medium to large sized river with wide floodplains in three dimensions by integrating discharge data and a highly accurate bathymetry. The primary objective is to quantify the friction coefficient and establish a reliable rating-curve for the river system. By utilizing these key components, the study seeks to provide a comprehensive understanding of the hydraulic behavior of the river, contributing to improved water flow predictions and management strategies. The bathymetry data is acquired through two different methods. The dry bathymetry is obtained using an UAV (DJI Phantom 4) and photogrammetry (WebODM). The wet bathymetry data is collected using both, sonar with the Deeper Chirp+ and spatial referencing with the RTK-GNSS from ArduSimple. These methods are cost-effective and require minimal manpower, making them practical options for acquiring accurate bathymetric information. The discharge data is acquired using the open-source software, OpenRiverCam. OpenRiverCam uses Large Scale Particle Image Velocimetry (LSPIV) to determine the surface velocities and combines the results with the bathymetry data to calculate discharges, providing an efficient solution for assessing river flow characteristics. LSPIV has the advantage that it is a non-intrusive method of measuring the flow velocity and does not require physical probes or instruments in the water. The bathymetry data and discharge data are integrated into the Delft3D FM Suite to assess the accuracy of the measurements and estimate the friction coefficient in both the river and the floodplain. This modeling approach enables a comprehensive analysis of the hydraulic characteristics of a medium to large sized river and supports the evaluation of flow resistance in the study area.
The data acquisition took place at three study sites close to the Bui Dam, in the Black Volta Region, Ghana. The Bui Dam is the second largest hydro-power dam in Ghana managed by the Bui Power Authority (BPA). The Bui Bridge and Bamboi Bridge study sites are positioned downstream of the Bui Dam, allowing for accurate quantification of the discharge and the bathymetry measurements. The third study site, Chache, is positioned upstream of the dam, where daily water level measurements are taken. BPA has observed that the rating curve at this location is outdated. Therefore, efforts are made to update the rating curve and quantify the friction coefficient at this site in both the river and the floodplain.
This research has made significant progress in developing a three-dimensional discharge model and rating curve for medium to large rivers using advanced data collection methods and integration techniques. The study successfully combined photogrammetry and sonar measurements to effectively determine the bathymetry of the river, overcoming challenges related to high water velocities and dense vegetation. The LSPIV technique and OpenRiverCam were utilized to integrate surface velocities and discharge measurements, leading to a more comprehensive understanding of river dynamics. However, limitations were encountered in assessing the accuracy of the model at the Bamboi Bridge site due to the LSPIV results. This highlights the importance of obtaining more comprehensive data and observations to enhance the model’s accuracy. The comparison of rating curves at the Chache site resulted in positive results. Although, further verification during the wet period is required through velocity and discharge measurements to determine the accuracy. Overall, this research contributes to a better understanding of river behavior and provides valuable insights for water flow prediction in an efficient, cost-effective manner with minimal intensive manpower, ensuring a non-intrusive approach. ... Read more

Polders water canals are sometimes exposed to brackish seepage from the nearby saline sea (salinization). This is a problem because the canal water is used to irrigate crops. A characteristic of water is that less dense (fresh) water floats on top of dense (saline) water. In lakes and oceans, it is common that water layers with various densities flow on top of each other (stratification). However, this has not been observed yet on a small scale, such as in polder water canals. It is assumed that, with a traditional weir, fresh water is discharged, and saline water stays behind. To encounter this, a modified weir is developed. It uses an underflow gate in front of the traditional weir to discharge the bottom water out of the canal. This research aimed to investigate if stratification happens in polder water canals and to explore how a modified weir can be implemented. The Negenboerenpolder in Groningen (the Netherlands) served as an example. Multiple methods are used because of the broad and practical nature of the problem. First, field measurements in the Negenboerenpolder demonstrated stratification in polder water canals. At multiple locations in the polder, the Electrical Conductivity (EC) is measured over the depth or continuously measured at two depths. Secondly, flume experiments gave information about the experimental procedure and implementation of a modified weir. Thirdly, 2D simulations of a modified weir are done in ANSYS Fluent, a Computation Fluid Dynamics (CFD) software. The simulations suggest that a modified weir works as expected, but the model is not completely representative. Observations are that such a weir is more effective in discharging brackish water with a low flow velocity and a larger distance between the underflow gate and the weir. Implementation advice for a modified weir is also included in this research. To conclude, this research implies that a modified weir can be used to discharge brackish water, but the design and implementation need to be done carefully. Recommendations for future research are to experiment with a modified weir in a polder and to build a 3D CFD model to investigate the flow around the underflow gate. ... Read more

With combined efforts from water management, architectural and hydraulic engineering students, an interdisciplinary and resilient design is set up for the Paraná Delta. The design relates to all the current environmental, architectural and flood risk challenges - among others, as well as the potential issues in the future since the Paraná Delta is a highly dynamic environment. ... Read more

Indonesia faces the challenge of attaining renewable energy goals and reducing carbon emissions by 29% by 2030. Despite a renewable energy goal of 23% of the national energy mix by 2025, only 14% of electricity production is projected to be generated from renewable sources by 2023. Accelerated deployment of renewable energy solutions is required to achieve these goals.

Indonesia has abundant renewable energy sources, such as hydropower, solar, and wind. Yet, a challenge arises from the difference between the electricity demand and supply patterns of these sources, which do not match throughout the day. Fluctuating energy supply patterns and variable energy demand necessitate using efficient Energy Storage Systems (ESS) to bridge the gap.

With its extensive coastline, Indonesia can potentially explore single reservoir Seawater Pumped Hydro Storage (SPHS), a variant of Pumped Hydro Energy Storage (PHES), as an alternative to solve these challenges. Similar to an enormous rechargeable battery, the reservoir in an SPHS system functions as an energy storage system. The system works by pumping up the seawater to the reservoir to store surplus energy during periods of ample supply and discharging it to generate electricity through a hydropower plant during periods of high electricity demand. This research aims to identify the ideal locations for SPHS systems in coastal areas of Indonesia. A Python GIS algorithm was developed to automate the selection process. The identified SPHS sites are then evaluated economically to ascertain their viability. The study concludes by comparing the carbon reduction potential of these systems to Indonesia's carbon emission reduction goals.

The research reveals 609 potential SPHS sites across Indonesia, with a total peak power that can be regenerated of technically potential sites of 29 Gigawatt-peak (GWp). Among these, 297 locations are deemed economically feasible, contributing a potential peak power that can be regenerated of 15 GWp. The peak electricity demand in Indonesia is approximately 44 GW, typically occurring at 8 p.m. The technical potential of SPHS promises an 11% reduction in carbon emissions from the energy sector, while the economically feasible sites could achieve a 6% reduction in carbon emissions projected in 2030. ... Read more

This research is aimed at creating a generic design method for infiltration drywells on sandy soils by acquiring knowledge on the functioning of these wells. Infiltration drywells are vertical infiltration pipes that are installed above the groundwater table and through which stormwater is drained to the subsurface. Infiltration drywells can have a prominent place in urban water management since they mimic processes that occur under natural conditions. In urban areas the hydrological cycle is altered due to impermeable surfaces. Utilization of infiltration reduces the effects of the alteration on the hydrological cycle. Hereby, reducing the risk on urban flooding and surface water contamination. Furthermore, urban heat stress is reduced by enabling more drought resilient vegetation through groundwater replenishment. Especially considering that climate change will result in more extreme weather conditions, infiltration facilities can aid in creating more resilient urban areas. Until now, there are no design rules for these wells which hinders the implementation in urban areas that are fit for infiltration facilities. In this research a design method for sandy soils in the Netherlands is created and set forth.

The theoretical and practical performance of infiltration drywells is analysed by conducting experiments with Hydrus 3-dimensional geohydrological model simulations, as well as in the field and laboratory. In the field falling head tests were performed with existing infiltration drywells to determine the functioning while soil samples were analysed in the laboratory to determine the hydraulic conductivity. The model simulations also exist of falling head tests and are compared to the experiments in practice. It was found that the most important parameters on functioning of infiltration drywells are the soil hydraulic conductivity and well dimensions. When comparing the simulated falling head tests to field tests and laboratory tests at the same location, discrepancies were discovered. This can be clarified by simplifications that were made like homogeneity and isotropy of the soil in the model. Furthermore, the absence of wall resistance of the well in the model and the method that was used for the calculation of hydraulic conductivity using in practice falling head test data could be the cause.

To this end the generic design method is based on the Hydrus 3D model. This design method consists of empirical contour plots that give the necessary number of wells based on multiple input parameters, including a design storm of 21 mm in 10 min, which has a statistical return period of 25 years in the Netherlands. Due to discrepancies in the research, the design method is used to test the viability of a plan to implement infiltration drywells. Afterwards, a detailed design procedure is still necessary. Overall, the research resulted in a generic design method and shows the advantages of using infiltration drywells, which could be an essential part of urban water management in the Netherlands in the future.
... Read more

The Netherlands has suffered form three successive dry summers resulting in a lowering of the groundwater table, causing water shortage. Also in the area of Water BoardDe Dommel, locatedwithin the province of Brabant, water shortage is a common problem. This results in water abstraction restrictions for farmers in the crop season every year. With climate change the precipitation pattern in the Netherlands will change, resulting in longer dry periods during summertime. Water Board De Dommel is searching for strategies to decrease this water shortage. These strategies need to be tested for future climate scenarios. This research tests different interventions for two specific areas within De Dommel. These areas differ in land-use, location in the catchment, geo(hydro)logy and infrastructure. This research answers the following research question: How does the groundwater of two different areas within Waterschap De Dommel react to different interventions
to prevent water shortage in long-termfuture scenarios?
To find the answer to this research question a stationary groundwater model (iMOD) is used. In this model
the different interventions are tested with four climate scenarios from the KNMI. These interventions take place in the top layers of the subsoil. Next to these interventions also three abstraction scenarios are modeled, to see the effect of changes in deeper aquifer layers. The interventions are tested with three signals from the model: 1) the head of the first aquifer layer, 2) the water balance for both areas for the first aquifer layer as well as the first four aquifer layers combined and 3) the flow paths. Because models include uncertainties and assumptions, expert judgement is included to test the interventions. The expert judgment is based on historical maps and the location of the interventions. At the end of the research a non-stationary model is used to test the "Brook swamp" intervention. This result is compared to the results of the stationary model of this intervention. The results show that changes in the top layers of the subsoil have almost no effect on the groundwater in the deeper layers for De Pielis area. More downstream in the catchment, at the Landschotse Heide area, this effect is bigger, because of changes in the upstream area. In the top soil layers the groundwater reacts positive for most interventions for both areas resulting in more water availability. Also in the top layers the effect is bigger at the Landschotse Heide area than at De Pielis area. With the non-stationary model results the groundwater reacts more positive to the "Brook swamp" intervention than for the stationary model. A non-stationary model is therefore better to see how the groundwater reacts to seasonal dependent interventions. The groundwater reacts differently per areas as well as per intervention. In both areas the groundwater does react positively to most interventions. For the Landschotse Heide area the groundwater reacts more positive than for De Pielis area. For both areas the "higher water level" and "closed ditches" interventions show the most positive reactions of the groundwater. Based on these results the Water Board is advised to research the effect of enriching the top layer of De Pielis, to see if these top layers can then hold more water. For the Landschotse Heide the Water Board is advised to decide if agriculture or nature is more important in that area, because these cannot coincide, and reach all demands, in the way it is set-up now. ... Read more

Flooding is one of the most damaging natural disasters worldwide, and presents a signi_cant risk for a large amount of the global population. For the development of ood disaster management strategies, policy makers make use of ood hazard maps to inform investment strategies to reduce risk. In many current ood hazard mapping methods, the role of embankments is either implicit or completely unaccounted for. However, these defense systems can play a key role in both the _nal extent of the inundation as well as in the development of the inundation. Limitations in available data are often the reason for the lack of explicit implementation of embankments. The goal of this study is the development of a method that can explicitly include the e_ects of ood defenses in a ood hazard map based on limited available data. Next, this has been tested for a low-lying riverine area and the Tisa river basin in Serbia was selected as a case study area for this purpose. First, an idealized approach has been followed to better understand the model behavior using settings resembling this river. Finally, the method has been applied with a more realistic river schematization.
To develop a method for a more explicit inclusion of ood defenses, an understanding of the di_erent current approaches has been generated based on a literature review. On the scale of global ood maps, the failure probabilities of ood defenses are not used. Only with post-processing, certain areas are considered protected by removing inundation from the maps. Many studies of ood hazard mapping use the so-called bathtub approximation. Hereby is assumed that the complete oodplain will ood and that the inundation depth is found by extrapolating the water surface level outside of the embankments to the area inside of the embankments. The inuences of the ood defenses on the inundation are not included. Regional ood hazard maps are still made without ood defenses in many cases. While the improved resolution allows for more detailed maps, the lack of available data still limits the implementation of ood defenses. Flood mapping methods exist that include failure probabilities for ood defenses but these require large amounts of data that is not available everywhere.
An idealized model based on the Tisa river characteristics is used to test a ood mapping method which includes explicitly the presence and potential failure of embankments. Based upon data on the river geometry, hydraulics as well as land-use in the oodplains, a model schematization has been set up with the SOBEK software. The embankments were simpli_ed to a crown height for the purpose of overow and an estimated failure probability. The breaching of the levee is simulated according to the Verheij-vdKnaap breach growth model. The estimation of the failure probabilities was based on historical failure rates of a comparable ood defense system along the Elbe River. The levees were schematized into segments based on the maximum breach width of the breaching model…
... Read more

Indonesia has a severe problem of fossil fuel dependency, making it become one the world’s larger carbon emission contributor. At the same time, the growing population will increase the energy demand in the future. Thus, in order to meet the energy demand and decrease the carbon emission, the government together with PLN as the state electricity company will committed to implement carbon neutral targets by 2060. Additional of 413 GW installed power capacity will be necessary in which 308 GW generated from renewable energy. Indonesia has many renewable energy alternatives that can be utilized such as solar, wind, biomass, and hydropower. Among various renewable energy alternatives, hydropower has emerged as one of the means to achieve the aforementioned targets. Indonesia has a hydropower potential of around 75 GW from large hydropower and 19.4 GW from small hydropower, meanwhile, due to a number of barriers, hydropower contributed only 7% from installed large-scale hydropower and 2% from installed small-scale power plants.

In order to reach the government’s goals, further study is needed to better understand the hydropower potential in Indonesia. Hence, the aim of this research is to quantify the potential of hydropower for Indonesia to find the possible location based on the economic consideration and to understand the positive influence of hydropower application. The analyses will be done using GIS-based modelling approach based on three DEM sources with 3 different resolutions, namely DEMNAS (0.27 arcseconds), USGS (1 arcsecond) and MERIT (3 arcseconds). The gross theoretical potential will be calculated based on the river discharge and the head of every pixel of the DEM. Further, the technical potential could be obtained by eliminating the output of theoretical potential with contraints area. Subsequently, the cost components (e.g investment and operational cost) will be added to the model to quantify the levelized cost of electricity (LCOE). The potential location that has LCOE lower the cost of power generation.

Based on the analysis, the theoretical potential in Indonesia ranges for approximately 159 GW to 182 GW, or in annual energy production amounts to 1400 TWh to 1600 TWh. Subsequently, the technical potential after eliminating the constraints area decreased to around 550 TWh (63 GW) – 700 TWh (80 GW). On the other hand, based on the technical potential results, the LCOE ranges from 1 to 69 cent USD/kWh. However, only around 45% of the total technical potential is economically feasible. Thus, the hydropower potential lowered to 240 TWh (10 GW) – 690 TWh (38 GW). According the results, hydropower could cover 9% to 25% of the total required additional capacity planned by PLN and could reduce the carbon emission around 90% compared to the carbon emission of fossil fuels. Since this study used three different DEM resolutions, the output of the analyses varies depending on the DEM used. Based on the results, higher resolution DEM could delineate river shape better and thus the location of estimated hydropower potential location could be more accurate. However, DEM with larger pixel size could detect better the medium and large hydropower potential ... Read more

Flash floods are a damaging and recurring problem in Cebu city, Philippines. Very little data is known about the intensities and precipitation amounts and the resulting river discharges. This research project firstly aims to gather as much data as possible on precipitation and river discharges that could cause the floods, it focuses on a small catchment in the city called the Mahiga catchment. Data is gathered by installing three tipping buckets and two trail cameras. The cameras were able to calculate the river discharges using an innovative open-source program called OpenRiverCam. Thanks to this program a hydrograph can be
made of the river for each precipitation event. The used cameras were trail cameras of the Brand Bushnell. During this project it was concluded that, due to their unreliability, using trail cameras with OpenRiverCam is really not recommended. Security cameras with a Raspberry Pi are more suited. Due to bad luck with the weather and faulty material only three different hydrographs could be made during our time abroad (10 weeks). These hydrographs however remained useful for the second part of this research project. The second part consists of modelling the discharge of the Mahiga catchment to different
precipitation amounts using HEC-RAS. HEC-RAS is a computer program meaning Hydrologic Engineering Center’s River Analysis System. The model has been calibrated using the gathered precipitation data from the tipping buckets and the discharge results from OpenRiverCam. Graphs have been made about discharges and accumulated volumes and rating curves. The accuracy of the model is reasonable but should be improved using more discharge events. What stood out was the high infiltration rate and the fast response time of the Mahiga catchment. In section three, the results from the HEC-RAS model are used to understand the impact gabion dams make on reducing the peak flow in the Mahiga creek.
The third part summarises the effectiveness of the gabion dams in preventing flash floods. Unfortunately there is no ’real’ flash flood event captured by the tipping buckets, so three precipitation events are used based on analog measurements of a tipping bucket nearby the catchment. The gabion dams are tested on a maximum precipitation intensity of 35 mm/h, 30 mm/h and 25 mm/h with a total amount of 40 mm. Higher amounts of total precipitation
are realistic, but have a larger time duration and are not considered flash floods anymore. The volume that gabion dams can retain is too little for these large amounts of precipitation and are therefore not in the scope of this report. The results show that with at least five gabion dams, the peak flow reduces for all above mentioned precipitation intensities, but for the 35 mm/h it is getting less effective. The model also showed that the effectiveness is very dependent on the volume that can be retained by the dams. Maintenance of the gabion dams is therefore of crucial importance especially with the large amount of sediments and
debris in the creek. ... Read more

For hundreds of years, ditch water levels in Dutch agricultural peatlands have been lowered to increase the loading capacity of farming parcels. This lowering results in groundwater levels in the middle of the parcels that fall a few decimeters under the ditch levels. When the groundwater level in a peat soil is lowered, newly uncovered peat is exposed to oxygen and begins to oxidise. This process emits greenhouse gasses (GHG), releases nutrients; like nitrogen and phosphorus that stimulate eutrophication, dries out the top subsurface layer and causes the land to subside. This study focuses on an island polder in Warmond, the Zwanburgerpolder, with a clay - peat subsurface. Half of the Zwanburgerpolder belongs to the Eenzaamheid, a biological cheese farm with the ambition to transition to a regenerative cheese farm. One of the key objectives to achieve this regenerative goal is to limit the GHG emitted from the farm. An analysis of the current (ground)water system of the Zwanburgerpolder was done which focused on limiting land subsidence by raising the groundwater level and thereby reducing the emission of GHG, improving (ground)water quality and stimulating biodiversity. First, four research components were examined through field experiments and literature studies: 1) water quantity, 2) water quality, 3) GHG emissions and 4) land surface displacements. The obtained results were used to understand how the Zwanburgerpolder works and identify the relationships between the four components. Then, two groundwater models were developed to represent the current groundwater level and flows in the Zwanburgerpolder: one in iMOD and one in FlexPDE. The iMOD model was used to get a visual representation of the groundwater level variations across the island and to see the groundwater response to precipitation and evaporation. The FlexPDE model was used to get an overview of the phreatic groundwater level drop between two ditches over the summer. To find the most suitable way to limit land subsidence in the Zwanburgerpolder, the models were adjusted to represent possible future situations. Instead of using the collected climate data of 2021 as input parameter, the projected climate data of 2065 was used. The future models consisted of a base scenario, in which no changes were made to the polder compared to the current situation and adapted scenarios, in which the following five water management measures were tested: 1. Adding ditches, 2. Installing horizontal drains, 3. Temporarily inundating parcels, 4. Installing vertical drains and 5. Raising the summer ditch water level. Temporarily inundating parcels performed the best quantitatively and qualitatively during the comparison of the measures. However, this measure is agriculturally unfavourable because as a consequence, parcels cannot be used for grazing during a significantly long period of time. For the Eenzaamheid, where regenerative practices and agricultural capacity take center stage, the recommendation for limiting land subsidence is to combine and adjust two measures: temporarily inundating parcels and adding ditches. Gutters that currently run down the center of the parcels should be enlarged and inundated during the summer period, by siphoning water from the boezem. Inundation can take place during the whole summer, since grazing is still possible alongside the gutters. It is recommended to start off by only applying the measures in the most critical parcels in order to use it as a testing ground to check the possibly negative effects of the measures besides the desired positive effects of limiting land subsidence, reducing GHG emissions and improving the (ground)water quality. Further, the results discussed in this report provide an interesting addition to peatland subsidence studies. They were obtained through field experiments done on a much smaller budget than other studies done so far with expensive measurement setups. The recommendation towards such peatland subsidence studies is therefore to apply a large network of lower cost measurement setups, instead of a few costly ones, in order to get an extensive representation of the behaviour of different Dutch peatlands. The main limitations in this study are the uncertainties linked to the parameters used to build the iMOD and FlexPDE models and the time constraint on the field experiments. The parameter uncertainties mean that the final model outputs fall within a certain error range. To minimize the error range, a model sensitivity and uncertainty analysis should be done. Without the field work time constraint, it would have been possible to identify the seasonal patterns in the groundwater level fluctuations compared to the other water bodies and in the land surface displacements. ... Read more

A green-blue roof consists of a water storage layer with on top a substrate layer covered with vegetation. Due to the presence of the water storage layer, a green-blue roof is better capable of retaining heavy rain events. A movable valve makes it possible to manage the amount of water on the roof and the timing of drainage from the roof to the sewer system, while in addition the stored amount of water is made available to the vegetation layer via a passive capillary irrigation system. This could potentially result in a higher evapotranspiration rate and therewith a reduction of the sensible heat flux compared to green roofs. Because of its qualities, green-blue roofs have been added to the list of measures that contribute to mitigation of the Urban Heat Island (UHI) effect and pluvial flooding. However, during dry summers a third climate related challenge arises namely drought. The question arises whether it is sustainable to increase the amount of vegetation in cities, as this increases the water demand during droughts. During long dry spells it can be challenging to store enough water for vegetation and cooling while keeping sufficient empty storage available at the same time. A conflict in water related functionalities of the roof is the result. It was the aim of this thesis to investigate how implementation of green-blue roofs can be made climate resilient by defining its strengths and weaknesses regarding temperature management and water consumption and come up with possible ways to improve the roof system. By conducting a measurement campaign in the summer of 2020, it was investigated if the presence of a water storage layer indeed enhances the cooling effect of a green-blue roof on the indoor and outdoor environment. Thermal fluxes at a green-blue roof and a conventional black roof were analysed, as well as two situations with either an empty of full water storage layer at the green-blue roof. Furthermore, a bucket model was designed to study the climate resilience of green-blue roofs for the climate scenarios of the KNMI for 2050. Based on the results, it is concluded that additional adaptation measures are required to make sure green-blue roofs can still contribute to a better and more resilient urban area towards the future. Several measures are available to improve the performance on water retention and drought resilience, like valve management, enlargement of the storage capacity on the roof or on ground level and irrigation. Closing the water cycle locally is important to make green-blue roofs self-sustainable in water consumption, which reduces the risk on conflicts on water use during droughts. Only regarding UHI mitigation, other measures like creating shade could be more efficient as the enhanced cooling of the urban area due to unlimited water availability is small, unless largescale application of green-blue roofs. ... Read more

The Meuse river facilitates important socio-economic functions. In the light of Integrated River Management (IRM), the question rises whether these functions can be facilitated in future decades (until 2050) as well. The riverbed is expected to degrade over the coming decades, just like in the past century. On top of that, the discharge regime will alter because of climate change. This research studies the impact of bed degradation and altering discharge regimes on the river functioning regarding navigation and flood safety. This is done by linking hydraulic river conditions to functional performance indicators.
... Read more

The central Thermo Electrico Antonio Guiteras (CTE Antonio Guiteras) is a thermoelectric power plant located in the bay of Matanzas. In 2017, hurricane Irma passed the north coast of Cuba and destroyed the primary sea defense in front of the CTE, causing major damage to the plant. The power plant is renovated, and a new and improved sea defense is currently being constructed.
The goal of this report is to answer the following question: to what extend is the power plant protected during extreme weather conditions and what improvements are needed to ensure that the power plant can remain operational during these extreme weather conditions?
To determine what the hydrodynamic and meteorological effects are of a extreme weather event such as a tropical cyclone, a synthetic tropical cyclone is created. This synthetic hurricane must generate large significant waves in combination with a big storm surge, to have severe impact on the CTE. It must also have a significant probability of occurrence. To determine this normative synthetic hurricane, multiple synthetic hurricanes are simulated in Delft3D and XBeach and their corresponding return period is determined. As Irma significantly damaged the CTE, this hurricane is taken as the basis for all synthetic hurricane combinations. The hurricanes each vary from Irma in maximum wind velocities, forward speeds and their tracks.
To simulate the physics of hurricane Irma, a spiderweb grid is created at the locations of the hourly best track of Irma. This is then used in the Delft3D model as input for the pressure and wind fields of the hurricane. The output of the Delft3D model is validated with recorded data of observations stations in the Gulf of Mexico. Recorded water levels and wind speeds of buoys near Key West are used for validation. XBeach is used to simulate the nearshore physical processes. XBeach can more accurately predict wave propagation and includes higher order processes in its simulation. As input for the XBeach model, the output of the Delft3D model is used.
After running all the synthetic hurricanes in Delft3D, the five resulting normative hurricanes are run in XBeach. The synthetic hurricane that creates the largest significant wave heights at the project area is taken as a basis for the final design. This normative hurricane gives a maximum significant wave height of 8.8 m with a corresponding storm surge of 1.61 m at the location of the CTE.
With these values a research on the current defense wall is done. Ultimately for a part of the sea defense an adjustment on the existing defense wall is proposed. A second but lower vertical wall with a bigger bullnose is placed in front of the existing one. This creates a triangular shaped stilling basin, from which the water can flow out at the seaside of the wall. For the other part of the sea defense no adjustments on the wall are proposed but an improvement of the existing drainage capacity is proposed. The existing drainage channel, which lies behind this section, is widened and deepened. Additionally, a drainage wall is built around the powerplant, which diverts the overland flow caused by intense rainfall into the drainage channel.
... Read more

In dit onderzoek zal antwoord worden gegeven op de vraag: Moet het falen van gemalen mee worden genomen in de watersysteemtoets? In de 6-jaarlijkse toetsing van de waterschappen wordt bepaald of het watersysteem voldoet aan de door de provincie opgestelde eisen voor wateroverlast. Op dit moment wordt er in deze toetsing geen rekening gehouden met het feit dat gemalen kunnen falen en dit falen invloed kan hebben op de wateroverlast. In dit onderzoek zijn de onbeschikbaarheid van gemalen en de gevolgen van deze onbeschikbaarheid in kaart gebracht. Met deze gegevens is het risico dat gemalen vormen voor het watersysteem bepaald. ... Read more

Plastic debris in water systems form a major problem for our ecosystem because it is extremely persistent in the environment and the global plastic production is still increasing without adequate measures to prevent pollution. Apart from the importance of reducing the amount of plastic entering the ocean, clearing the rivers from debris is important for societal concerns, such as health related issues and flood risks. The interaction between riverine debris and the hydrodynamics of water systems plays an important role in the construction of trash racks that can block water flow in the river. These clogged trash racks lead to an increase in upstream water level and can cause regional flood risks. This study was set up to investigate the amount and accumulation of riverine debris in the Cikapundung River in Indonesia, one of the tributaries of the Citarum River.

The Citarum River is one of the world’s most heavily polluted rivers, predominantly caused by industries and households dumping their waste directly in the river. With a length of 270 kilometers, this is the longest river of West-Java and it is the main source of water for 27 million people. The river flows through three reservoirs and the area upstream of these reservoirs is called the Upper Citarum River Basin. The main contribution of pollution comes from this area, as the city of Bandung is located in this area. The Cikapundung River flows through the city of Bandung and is one of the tributaries of the Citarum River. This river was selected for the field measurements in this study as it allowed measurements to be performed in river parts with rural and urban areas neighboring the river.
Up until now, many studies of riverine debris accumulation are predominantly focused on organic debris accumulations at bridges and gates. This study also investigated plastic debris accumulations, as it forms a significant part of the debris in the Cikapundung River and other Asian rivers.

Field measurements in the Cikapundung River were performed with a single and double trawl, to determine the riverine debris composition and flux. Scaled laboratory tests were carried out, to (1) monitor the blockage growth process for different debris compositions, (2) investigate the influence of different parameters on the upstream water level and (3) determine the impact of a blocked trash rack on regional flood risks.

From the field measurements, an increase in downstream direction was found for the debris flux, but the debris composition varied in both time and space. The plastic debris mass varied between 11\% and 78\% of the total debris mass.
Based on the laboratory tests, the behavior of riverine debris is studied during normal flow conditions and in front of a trash rack. One of the key findings from this study is that plastic debris causes a faster blockage than organic debris, as the plastic blockage contains fewer voids and therefore has a higher blockage density. In the formation of a blockage in front of a trash rack, a mix of organic and plastic debris behaved more similar to plastic debris. The shape of the blockage was also found to be different for plastic and organic debris: a high amount of plastic in the debris lead to an angular blockage shape, whereas mainly organic debris produced a curved blockage shape.
The most important indicators for flood risks related to debris accumulations were found to be the debris load, loss coefficient, initial flow velocity and initial flow depth. By rescaling the results to the case study location in Bandung, it was found that a backwater rise within the hour of O(1 m) is plausible for a blocked trash rack.

This study forms the stepping stone to further quantifying riverine (plastic) debris and investigating its relation to changes in the water system behavior, including its influence on regional flood risks. ... Read more

Because the earth loses her heat less efficient, the average global temperature rises. As a result, more extreme weather conditions occur. In urban environments, rain during these extreme weather conditions cannot be discharged immediately. A Polder Roof, a combination of a blue and green roof, provides a solution for this problem. This roof stores water under a green layer consisting of soil with vegetation. A Polder Roof is difficult to sell, because the investment of an user is earned back long term and the water storage does not have a direct influence on the user. This study aims to investigate the possibility to add a direct function to this water storage, by harvesting or transfer thermal energy out of or into this water, to heat or cool a building energy-efficiently.
To heat a building, a certain heat input is necessary to keep the building on the same temperature. This heat demand can be determined by standardized yearly values used in the sector. If these are distributed monthly over a year, a mean heat demand per second can be determined. This heat demand is provided by harvesting heat out of the water on the roof by using a heat pump. Therefore the temperature of the water changes. To state that the water may not turn into ice, a maximum daily heat drainage can be calculated. The total amount of thermal energy which can be harvested is determined by the water’s temperature and volume. The temperature of the water is influenced by the temperature of the air in contact with the water, incoming radiation and outgoing heat from the building underneath. The volume rises through precipitation on the roof and lowers by evaporation and the discharge from water of the roof. The influence of the air on the water temperature is modelled with the Cooling Law of Newton.
By modelling the described system, an equilibrium temperature difference between water and air can be found with a given heat demand. When cooling is needed, this difference will also occur because the heat pump transfers heat into the water and is cooled by the air. This method for heating a building can be used from March to November in the Netherlands. By using another isolation layer which can retain more radiation instead of the green layer, the applicability can be increased. Cooling with a heat pump can be applied if the cooling demand is low. A high water temperature is adversely for the efficiency of the heat pump and the vegetation. Because a Polder Roof isolates a building better than a conventional roof, the building has a lower cooling demand, so the temperature of the water will rise less. The use of a heat pump is more energy-efficient than a conventional installation, on the condition that the COP is higher than 1.33. ... Read more