Foresight used in the current developments of the Zwolle region limits itself to short-and-medium term foresights. Based on the hypothesis that prioritizing decision-making based on short-term, risks and opportunities may inadvertently omit crucial factors, while a focus on longer-term perspectives enables a more comprehensive understanding of complexity and uncertainty, questions the robustness of the developments. Therefore, this thesis conducted a case-study to assess the durability of current and novel development directions of the Zwolle Region focussed on distant-future sea level rise scenarios to amplify anticipatory consciousness, and therefore broadening the scope of policy directions for decision makers. For this, this thesis turned to the question: How robust are the current proposed development directions of the Zwolle Region compared to Sea Level Rise scenarios up to 2300? Based on a systematic grey literature an overview of the novel development directions of the region have has been created. According to a Dynamic Adaptive Policy Pathways analysis, the developments were compared to distant-future sea level rise scenarios that were based on interim KNMI sea level rise scenarios and semi-structured expert interviews. Following the analysis, it was determined that the proposed development directions assume the existing condition of the regional water system. Given the projected rise in water levels due to SLR, which is expected to significantly impact the regional water system, leading to increased moisture and frequent flooding, this thesis asserts that the current proposed developments lack robustness.

The Dutch Rhine-Meuse delta is expected to require many dike reinforcements on a short and long term, due to (accelerated) sea level rise. Average damage in unembanked areas will increase too, and a costly replacement of the Maeslantkering is expected after 2070. Delta21 is a project that aims to address these challenges related to flood protection, while also providing hydraulic energy storage and opportunities for valuable nature development.
Delta21 consists primarily of a large (salt)water storage lake attached to the Tweede Maasvlakte. It is connected to the North Sea with a pump-turbine station. On the southern side, a closable storm surge barrier spans the remaining gap to the island of Goeree Overflakkee. Under normal circumstances the lake functions as a hydraulic battery, using the pumps and turbines to store or generate electricity as needed. However, when water levels threaten to exceed NAP + 2.5 m at Dordrecht, the barrier closes and an upstream spillway into the lake is opened. To determine the viability of the project in the context of flood protection, the question arises: “To what extent is Delta21 capable of providing a cost-effective alternative to the current flood protection policy in the Rhine-Meuse delta?”
To answer this question, a one-dimensional hydraulic model is constructed with a detailed and accurate schemati-zation of Delta21. Results are processed into exceedance frequencies for a system with and without Delta21, to obtain reductions in water levels at normative frequencies. Furthermore, a sensitivity analysis is performed to de-scribe how various designs and configurations affect the magnitude of these reductions. Other than Delta21, no system-changing interventions are included in the scope of study.
Three strategies are formulated in which Delta21 potentially reduces costs, and evaluated using the model’s results:
1 Extending the lifetime of the Europoortkering before it needs to be replaced.
2 Obviate dike reinforcements.
3 Reduce the average yearly damage of unembanked areas.
Approach 1 is shown to be ineffective. Delta21 does not achieve changes in the Europoortkering’s closure frequency or failure probability per closure. Neither does Delta21 effectively mitigate a failure in the region where water level exceedance frequencies are dominated by the Europoortkering’s failure probability.
Approach 2 is far more successful, accounting for 96% of the total cost reductions. Reductions in water levels at normative frequencies are translated to reduced failure probabilities of dike segments using fragility curves, which potentially yields a positive reassessment. Delta21 achieves this and obviates dike reinforcement for 41 km by 2050, and 150 km more by 2100. These lengths comprise respectively 33% and 60% of the total considered dike lengths that would need reinforcement. The net present value of obviated reinforcement costs is €752 million, with a 90% confidence interval of [€220 million, €2,821 million]. This large interval is due to large uncertainties in reinforcement cost estimations. Delta21 most effectively obviates reinforcements in trajectories with stricter norms and closer proximity to the storage dominated region. Water levels at normative frequencies are very sensitive to the opera-tional control (i.e. closure criterion) of Delta21. An additional nominal cost reduction of ca. €278 million can be achieved when a criterion of NAP + 2.5 m at Dordrecht is maintained in the future. The sensitivity is far weaker to varying dimensions or capacities of Delta21, which are generally unnecessarily large during illustrative conditions.
Approach 3 provides the additional 4% contribution to total cost reductions. The only considered area is Dordrecht, due to its unique high economic value in low lying unembanked locations. Damage profiles are integrated with changes exceedance frequency curves to obtain the average yearly damage. This is reduced by approximately €53,000 per year now, and grows to €1.36 million per year in the future climate scenario (2100). The decrease in relation to the current system is about 42%, but the absolute value rises greatly with sea level rise. Implementation of lower closure criteria variations can yield an additional +20% now, and +10% in the future scenario.
The total net present value of cost-reductions by Delta21 is €783 million, with a 90% confidence interval of [€251 million, €2,852 million]. This covers about 20% of the total construction costs of €3.7 billion, and is insufficient to make Delta21 viable alone. However, not all costs are related to flood protection exclusively. If the components required for energy storage are viable on their own, merely the additional costs of the spillway and storm surge barrier have to be included in the cost-benefit analysis. Operational costs, which heavily depend on the operational control, must also be added. Smaller design dimensions or pump capacity of Delta21 has been shown to be just as effective, and would further cut costs. Additional savings beyond 2100 are plausible, but outside of this research’s scope. Furthermore, less people displacement or flooding of unembanked areas may achieve additional societal value, but is difficult to quantify. More research will have to indicate whether attributing only specific costs, including additional value sources, and estimating reinforcement cost more accurately ultimately lead to Delta21 being fea-sible in the context of flood protection.

Climate change and its impacts have necessitated a shift from relying solely on mitigation measures to implementing effective adaptation strategies. The financial requirements for adaptation, particularly in developing countries, have increased substantially. The annual projected needs for adaptation have nearly quadrupled over the past decade and are anticipated to reach significant amounts by 2030 and 2050. Sea level rise is considered a critical threat, and allocating financial resources efficiently becomes challenging due to the uncertain nature of SLR. Adaptive pathway planning, which allows for flexible decision-making over time, offers a promising approach to develop flood risk reduction strategies that can adapt to changing circumstances. However, evaluating the effectiveness of adaptive pathways requires accounting for uncertainty, using multiple evaluation metrics, and considering the value of time. To address these requirements, a new framework for evaluating flood risk strategies was established, incorporating Monte Carlo analysis to incorporate uncertainty and several evaluation metrics including NPV, BCR, EAC, POL, and CV. The framework emphasized the importance of decision moments, where new measures are required, and the balance between flexibility and costs. A conceptual case study involving seven strategies was conducted to test the framework, and sensitivity tests were performed to assess its robustness. The results demonstrated the framework's effectiveness in capturing uncertainty and the value of time, providing a solid foundation for further research. However, certain aspects of adaptive pathway planning, such as preventing future lock-ins, were not quantified in this analysis. Future research should focus on refining and validating the framework through real-world and more complex case studies, evaluating the performance of adaptive pathways, and incorporating various stochastic variables. Additionally, a comprehensive assessment of the entire flood system, encompassing both pluvial and fluvial flood risks, is crucial. Once refined, the framework has the potential to serve as a valuable evaluation tool, enabling the comparison of static and robust strategies against more flexible adaptive strategies, and facilitating decision-making in flood risk management.

Due to an extraordinary precipitation event in July 2021, the Dutch government want to utilise the temporary flood barriers to reduce the impact caused by a flash flood event in the future. As a result, Water Board Limburg, Flood Proof Holland and Delft University of Technology made an agreement to conduct a physical experiment in Roermond on May 2023 to test the functionality of the temporary flood barriers in different spatial conditions.

This report aims to provide a comprehensive understanding of the temporary flood barriers and their performance in spatial variability before the experiment. To achieve this, available information on various barriers has been summarised to make a valid argument for the comparison of different barriers.

The first part of this report provides an overview of worldwide available barriers with their corresponding physical concepts explained, while more detailed information is given on those tested in Flood Proof Holland. The report then presents a theoretical hypothesis based on the calculation of the resisting force of the barriers. The findings reveal that most of the tested barriers can withstand a water level of 50 cm on asphalt, concrete, sand, and grass. However, BoxBarrier and BoxWall(Waterschot) show exceptions when subpressure is taken into account.

The report also includes a comprehensive outline of a physical experiment that will be conducted in May 2023, which provides a detailed description of the experiment, as well as preliminary assessment criteria. These criteria include logistics, failure mechanisms, spatial conditions, and additional requirements from the water board, and will be used to assess the performance of the temporary flood barriers. Additionally, an ideal monitoring plan utilising video camera, tracer fluid, and RBR-Diver has been proposed for the experiment.

Lastly, the report features a discussion of a preliminary test conducted on February 15th 2023 in Flood Proof Holland, to evaluate the effectiveness of the designed monitoring approach. The test proved that the proposed monitoring plan was successful and emphasised the significance of proper equipment inspection, anchoring, and quality control of materials for the temporary flood barriers.

Between July 12 and 15, 2021, extreme rainfall in Luxembourg, Belgium, Germany, and the Netherlands caused severe flooding. The total damage in the Netherlands is estimated to be between € 350 and € 600 million, with Valkenburg aan de Geul suffering the most damage. The economic and tourist heart of this city is located in the lowest part of the valley, therefore developing a flood reduction measure is challenging due to the limited space and restrictions in this location to protect the culture and nature.

In previous studies, different solutions were proposed for reducing the flood risk such as flood walls in Valkenburg; however, due to the locational difficulties, many options are difficult to implement except for the option of a flood bypass tunnel. A flood bypass tunnel has never been applied in the Netherlands, however; it is applied in mountainous countries. A flood bypass tunnel rapidly conveys floodwaters through densely populated areas. For Valkenburg, a flood bypass tunnel will reduce the flood risk locally while taking up little space and keeping the historic district intact.

Recent research did not look further into the opportunity of a flood bypass tunnel as a flood measure assuming it would be too expensive (Asselman & van Heeringen, 2023). However, different studies concluded that a flood bypass tunnel is a viable option (Van Dijk, 2022; Kallen et al., 2022; Leijser & Nijhof, 2022). Nonetheless, a flood bypass tunnel has never been applied in the Netherlands, and there is no prior research detailing the hydraulic and operational applicability of a flood bypass tunnel for Valkenburg aan de Geul. The main objective of this thesis is therefore to develop a hydraulic flood bypass tunnel design for Valkenburg aan de Geul which should operate to reduce the flood risk.

The objective is reached by combining the design approach for hydraulic structures with a Systems Engineering approach. First, the river system and its environment are analysed. Secondly, the basis of the design is determined. Thirdly, two alternative designs are developed from the two different types of reference projects: a passive and an active flood bypass tunnel.

The first design alternative is based on a passive flood bypass tunnel. It consists of a 2.4-meter-tall and 24.5-meter-wide Ogee weir, two tunnel tubes of 3.5 m diameter, and allows for a maximum discharge capacity of 55 m³/s. Once the tunnel is filled, the flow is pressurised. After a flood, the remaining water will be pumped out. A co-current channel is designed to prevent water from refilling the tunnel from the outlet side in a non-flooding situation.

The second design alternative is based on an active flood bypass tunnel. It consists of four vertical moving flat gates at the inlets and outlets, two tubes of 3.5 m diameter, and allows for a maximum discharge capacity of 58 m³/s. The water level will be controlled by the flat gates using a system for early automatic detection of flood hazards. The tunnel is always filled, thus pressurised. After a flood, the gates at the in- and outlets will close off the tunnel from its environment. The gates are tested twice a year, during which the system is flushed and refreshed.

The two design alternatives were evaluated according to six weighted criteria and ranked using a multi-criteria analysis in discussion with the municipality (gemeente Valkenburg aan de Geul) and the waterboard (waterschap Limburg), and a cost analysis was conducted. The first design alternative with the passive flood bypass tunnel was selected due to its high reliability and serviceability, which were highly valued, and low maintenance costs, compared to the second design alternative

The flood bypass tunnel reduces the flood risk based on discharge reduction from an estimated once every 19 years to once every 250 years in the current climate. This accounts for uncertainty due to climate change and ensures flood risk reduction in the future. The flood bypass is only active when a flood is impending; hence the water remains to flow through the Geul and does not interfere with the cultural heritage and tourism of Valkenburg aan de Geul. Due to the cost-efficient pipe jacking method, the total construction cost is approximately €40 million with an estimated yearly maintenance cost of €100 k.

In the area of Bunde in the south of Limburg, the Netherlands, the Geul river flows beneath the Juliana Canal through an inverted siphon before reaching the Meuse. During July 2021 a large scale flood event occurred, showing an insufficient capacity of the inverted siphon when both the Geul and Meuse had high water levels.

Such inefficiency can be explained by the significant head losses at the entrance due to a sub-optimal geometry that also favours the accumulation of debris, as proved during the recent flood. Therefore, the purpose of this study is to investigate the hydraulic behaviour of the Geul inverted siphon, focusing on potential implementation measures. Additionally, this study investigates the possibility of replacing the current inverted siphon with a Minimum Energy Loss (MEL) culvert.

The combination of climate change and increased urbanization has resulted in cities with no historic flooding experience suddenly vulnerable to extreme flood events. Climate change increases the frequency and intensity of rainfalls, whereas urbanization decreases the total porous surface area, resulting in pluvial (rainwater) flooding. One such affected city is Valkenburg, located in South Limburg in the Netherlands. Valkenburg flooded on 14 July 2021 after experiencing an unusually heavy rainfall that deposited 146 mm of rain into the Geul Catchment, causing up to €600 million in damage. In such communities, flood early warning systems (FEWS) are emerging as possible non-structural solutions to minimizing costs of damage and loss of life from flooding. These systems are people-centered, end-to-end networks that predict floods before they are meant to occur to warn people living in vulnerable areas so that they can protect their homes, businesses, and themselves. 
The FEWS network for the Geul uses forecasted precipitation data to predict discharge and water level conditions for the Geul. In the event that the predictions result in an abnormally high water level, warnings can be communicated to the necessary parties and to the population to allow for ample preparation. At the time of the July 2021 flood, the system was offline, with experts familiar with the network believing that it would not have worked even if it was online. This project aimed to analyze the existing FEWS from data collection to communication of warnings to locate existing issues and potential sources of weakness, thereby improving the system to effectively warn for future floods. 
Each step of the FEWS was tested to find and strengthen potential weaknesses. The data inputs were analyzed and compared to the recorded precipitation that occurred in July 2021. Then, this data was inputted into the FEWS prediction models to understand how the system would have calculated the discharge and water level for that event. Both the July 2021 flood event as well as four non-flooding scenarios (summer storm, winter storm, dry season, wet season) were tested. The models were then used to create a flood map, and this flood map was inputted into the Damage and Casualties Model (SSM2017) to estimate how much in damage costs could be saved for the case with FEWS and the case without FEWS. Communication and evacuation were not extensively tested in this research project due to these components being determined by social and political frameworks. 
When inputting the precipitation data associated with the July 2021 flood, it was found that the 1D model overestimated the water level to be 76.5 m+NAP, 6.5 m greater than the expected water level. Implementing a 2D grid reduced this value to 70 m+NAP, which matched the expected water level. It was also found that both HBV and SOBEK produce simulation results that consistently do not align with recorded data, suggesting a need to recalibrate the models to better reflect the behavior of the Geul River. Analyzing the recorded discharge and precipitation data found that using forecasted precipitation data gives Valkenburg enough time to communicate warnings and evacuate if necessary. Cost-benefit analysis that compared the economic impact of warning versus not warning revealed that warning and evacuation is more cost-effective than not not warning and evacuating, even in the case of a false alarm. An evacuation in the event of a false alarm can cost 1/10 of the difference in damage costs with and without evacuation. However, false alarms must still be avoided, as they erode trust in the warning system, thereby reducing its effectiveness in possible cost and loss of life reduction. Analysis of the expected costs of damage with and without the warning system revealed that the inclusion of the warning system has the potential to reduce the total expected damage by more than 50%. 
The insights found in this project can be used to improve the FEWS for the Geul. Future research can be done to create a 2D or quasi-2D model that can predict the discharge and water levels of the Geul in a timely manner (no more than one-two hours’ simulation time). The 2D aspect is important to a warning system as the expected amount of water affects how the community prepares for the disaster. This project can contribute not only to the improvement of the FEWS for the Geul but also for the improvement or creation of FEWS for other river catchments in newly vulnerable cities.

Flood risk models are frequently used to analyse the climate- and socio-economic-driven impact of flooding hazards. However, model validation is rarely done adequately due to the rare occurrence of floods and even less frequent reporting of corresponding damages.

In this research, validation is defined as the process of ensuring that a model performs within a range of accuracy and precision, satisfactory for its intended use. To guide experts in their validation efforts, a four-phased framework is developed to validate flood-event damage estimations, created with hazard x exposure x vulnerability models.

The framework was applied to two damage estimates created by the Global Flood Risk Tool (GFRT). 1) For damage caused by the Limburg 2021 river flood (The Netherlands - Europe) and 2), for damage caused by a 2019 hurricane-induced coastal flood in Beira (Mozambique - Africa). For the Limburg case, total direct damage was determined at 349,4 million euro. An initial model overestimation of 34% was caused primarily by a large exaggeration of exposed agricultural surface area, and significant modelling errors of linear infrastructure. Furthermore, an uncertainty range was quantified between 271,8 (-23%) and 388,2 million euro (+11%) due to uncertainty in residential assets (across all three model parameters) and an uncertain exposure parameter of agricultural assets.

To create additional damage estimates for verification, a Structured Expert Judgement (SEJ) experiment was executed with ten flood-damage experts. Due to the high experiment cost and low expert-informativeness, the method is currently not advised as a validation approach. In situations with limited data, experts may still be a relevant information source.

For Beira, damage was determined at 8,1 million US dollar. The model underestimated damage by 82% due to errors in infrastructure, industrial, and commercial assets. Besides, overestimations were found for informal residential- and agricultural assets. The estimate ranges between 5,2 (-36%) and 13,2 million US dollar (+62%). This range excludes uncertainties at port and industrial assets, as insufficient information was available. Contrary to the Limburg case study, insights from the plausibility assessment were too uncertain for quantification, thus the validated estimate is based on damage- and construction cost data. Novel techniques were used to disaggregate the compound damage data, such as comparing wind and flood vulnerability curves and applying employee-based estimations.


The significantly altered damage estimate for both case studies demonstrates the usefulness of the framework. However two main limitations remain: first, lacking information on direct damage to critical infrastructure hinders validation.
Second, additional detail in data is required to allow parameter calibration that increases accuracy across multiple flooding scenarios. Therefore, the main recommendation for future research is to increase the detail in damage data reporting so that parameter calibration is supported. This may be done by increasing the spatial resolution of reported damages or adding additional variables such as inundation depth in reports.

Major flooding occurred on the Meuse River in 1993, 1995 and 2021, causing significant damage to regions in NL, BE, DE. The flood events of 1993 and 1995 occurred in the winter, while that of 2021 occurred in the summer. There are large differences in the characteristics of these floods separated by nearly three decades; not only the seasons differ, but the topography of the river bed and the shape of the flood wave have also changed. Since 1995 dikes and flood-routing measures have been constructed along the river. Although all these projects are not yet completed, the flood event of July 2021 indicates that the Meuse projects are producing the expected results. This research aims to understand the effect of the shape of the flood wave during a high-discharge event, the impact of the different types of flood protection along the river and the interaction between the main river and its tributaries. The main research question is: what are the hydrodynamic differences between the high-waters levels on the Meuse in Limburg in 1993, 1995, and 2021, and how can these differences be explained?
The first step to complete this research was to gather the needed information. The second step is to identify the differences between the different flood events and assessing the impact of the different flood protection measures. The third step is to assess the impact of the different flood protection measures.
After an analysis comparing inundation maps, five flood prone areas were identified and investigated, namely: Maastricht, Bunde and Meerssen, Maaseik-Roosteren, Roermond and Venlo. Flood wave characteristics play an important role: the width illustrates the duration of the event, while the height indicates the maximum water level that can be expected.
Theoretical predictions of flood wave behaviour derived by scenario-based simulations with hydraulic models (i.e., report of peak attenuation, evaluation of the Grensmaas and the tool Box of building blocks) were compared with measurement data, water levels, discharges and inundation maps in order to assess if intended effect of certain measures correspond with the measured effect of the flood events of 2021.
The flood event of July 2021, the amount of water already in the river system, before the heavy rainfall in the southern part of the Netherlands, Ahr-Eifel region in Germany, Luxemburg and Eastern part of Belgium, was only approximately 200 m3/s instead of the 600-700 m3/s in 1993 and 1995. This means that there was a large buffer, before the water level increased to dangerous levels. Secondly, the short duration of the flood event in 2021 compared to 1993 and 1995 the increased role of peak attenuation. The flood routing-measures have helped to increase this effectivity due to the fact that more water could be stored in floodplains, high-water channels and retention areas.
For this event it can be concluded that the duration of the flood event in combination with the already executed flood-routing measures have prevented further flooding.

Hydropower plants have proven to generate electricity reliably and predictably, store water to meet water demands during dry periods, improve navigability and reduce flood risk. The reservoirs of these hydropower plants face ongoing sedimentation, negatively effecting the electricity generation, water storage volume, navigability and flood risk. Obtaining an equilibrium of the in- and outgoing sediment flux reduces these negative effects.

The incentive for this report is the planned run-of-river hydropower dam cascade in the main stream Mekong river in Lao PDR. The Mekong river is characterised by the distinct low and high flow seasons and a unique ecosystem. At the location of the planned cascade, the river is located between mountains and the river bed consists of bedrock with alluvial bed forms at the banks and between rock outcrops.

Long, narrow and relatively shallow reservoirs are created due to the construction of the planned dams in the main stream Mekong. Flushing operations have proven to be an effective method to recover reservoir volume from rivers with a high season flow with long, narrow and shallow reservoirs. The Mekong river in Lao PDR has all those properties.

This report attempts to determine operational rules for a run-of-river hydropower dam cascade to increase the sediment flux by flushing operations at the dams, whilst still maximizing the electricity generation.

To do so, two steps are taken. Firstly, a set of experiments on the Mekong river and flushing events at a dam is performed in a Delft3D-FM software with the Real Time Control module. The output of these experiments are used as input for a bucket model with volume conservation to test different operational rules.

Using the Delft3D-FM software with the Real Time Control module, a one-dimensional representation of the Mekong river is made. This model is used for two purposes. First, the reduction of the sediment flux is determined by comparing the sediment flux during a representative year for the situation pre-dam and post-dam construction. Secondly, this model is used to test the influence of the draw down rate, water level set point and duration of flushing operations on the cumulative sediment flux through a dam for four different discharges. The results of the flushing experiments will then be used as input for the second step of the research, the bucket model.

Different simulations are performed using operational rules with different threshold discharges for initiating flushing events, different draw down rates and different frequencies of flushing a reservoir. Using random sampling the influence of these three variables is tested. Additionally, two predetermined strategies are tested and compared to the operational rules tested using random sampling. In the first strategy the dams in the cascade are flushing progressively from the most upstream dam towards the downstream dam. The second operational strategy flushes the reservoirs progressively starting from the downstream dam towards the most upstream dam.


Obtaining free flowing conditions during a flushing event increases the sediment flux significantly compared to flushing events that do not reach free flowing conditions, especially for lower discharges. Increasing the draw down rate proves to have limited influence on the sediment flux further upstream in the reservoir, while the flood wave released at the dam increases. Extending the duration of free flowing conditions after draw down proves to be an effective method to increase the sediment flux at the lowest reducing in electricity generation.

Performing a flushing event with 48 hours at free flowing conditions during the flood season increases the yearly cumulative sediment flux on average by a factor three. The cumulative electricity generation is reduced by just 2.5 %. Extending the duration of the free flowing conditions in a flushing event increases the sediment flux per lost GWh electricity generation.

Current operational rules at the planned cascade in the main stream Mekong do not consider flushing at all. It is recommended to include flushing events in the operational rules which are initiated if the discharge is above the design discharge of the turbines and below extreme discharges to increase the sediment flux and minimize electricity generation loss.

The United Nations (UN) Sustainable Development Goal (SDG) \#6 reads that by 2030 universal and equitable access to safe and affordable drinking water is achieved for all In order to achieve this goal, proper and complete monitoring, capturing all the facets of safe water access, is essential. In this thesis it is argued that the current monitoring techniques come with limitations and subsequently solutions are presented to come to a more complete picture of water access.

Monitoring safe water access happens primarily through household health surveys. These surveys are often incomplete, not covering entire nations, focus on only the primary water source and are often spatially aggregated for privacy reasons. Besides, health surveys almost never include questions on consumed water volumes while that is an important indicator for proper hygiene (WELL, 1998), and something that, at the same time, should be in balance with the natural available water resources. Next to this survey based monitoring, there is the Water Point Data Exchange (WPDx) that monitors safe access by providing a platform at which the exact location and type of water access points (such as boreholes, springs, etc.) are registered. This does give more insight into the presence and usage of a variety of sources, but also the WPDx is often incomplete: not covering entire nations.

In this thesis we present a dual methodology that gap-fills the incompleteness of the WPDx database through modeling and in parallel, researches the complex local dynamics of water access, the variety of water sources used by households and the relationships between access and water consumption by means of a household survey.

By improving a machine learning biological species modeling technique (called MaxEnt), successful predictions on the number of presences of eight different water access types across Uganda were made, also into areas that have little presence in the WPDx data. It was found that population density, precipitation, elevation, poverty and groundwater storage are important indicators for the (non)presence of water access points.

Next to modeling, a survey campaign was executed in Bushenyi-Ishaka municipality, a mid-sized town in the South West of Uganda comprising a mixture of both urban and rural areas. This was done in collaboration with Makerere University (Kampala). The survey results showed that water consumption increases with education and wealth, but also with higher number of water point presences predicted by the model. It was also found that households in Bushenyi make use of an average of two different water sources on a regular basis and often express preference for sources off premises compared to on premises (piped) for both cost and perceived quality reasons.

Lastly, modi operandi were suggested for the results to improve water access such as prioritising areas with poor(est) water access and investing in rainwater harvesting, infrastructure and education.

Climate change is causing the global sea level to rise. Research and discussion of the effects of sea level rise are often focused along coastlines. However, the effects of higher water level and changing morphodynamics can reach far inland via rivers. This study uses a one-dimensional numerical model to analyze bed level response to sea level rise. The model simulates 100 years of steady sea level rise on a 1000 km long, fixed width channel. Sea level rise creates a backwater curve which grows in the upstream and vertical directions. The transient response of the channel bed is an aggradation wave the grows in the upstream and vertical directions. We studied different cases which vary in sediment flux, flow discharge, grain size, and rate of sea level rise and found changes in the rate of growth of the aggradation in both directions. All runs start in an equilibrium state and run for 100 years.

This study finds a close relationship between the equilibrium slope and depth of the channel and the shape of the backwater curve. This relationship drives the aggradation patterns. For example, for the same amount of sea level rise, a flat, deep channel has a longer backwater curve with a smaller relative increase in depth than that of a steeper, shallower channel. The backwater curve drives the aggradation patters, such that the flat, deep channel then has aggradation over a longer reach, and a smaller increase in bed level than the steeper shallower channel.

With the cases modeled in this study, three general trends in aggradation rates emerge: (1) an aggradation mound that grows quickly upstream, with slower increase in bed level as found in flatter, deeper channels; (2) a faster increase in bed level with slower upstream growth, found in cases with steeper slope and shallower depths; and (3) faster growth in both bed level and upstream direction caused by an increased rate of sea level rise.

Since natural channels are often complex with multiple sources of discharge inputs, a tributary case is also
included. Starting from equilibrium state and applying sea level rise to the downstream boundary, the model
shows aggradation waves in the regions downstream and upstream of the confluence, starting from the downstream boundary and the confluence. There is also degradation just downstream of the confluence. The scour hole grows at first, in depth and the downstream direction then reduces. The aggradation moving upstream intersects with the degradation moving downstream and fills in the scour hole. In some cases, we see the scour fills in within the 100 year time frame, resulting in a net increase in bed level. In a tributary system, the risk of scour is greatest for tributaries with high flow discharge or low sediment flux.

The transient response of the bed level to sea level rise is aggradation. As the water level continues to rise, the bed level is expected to do the same, but at a lower rate. In this study, the nominal rate of sea level rise is 10 mm/yr. The fastest rate of bed level rise in the model results is less than 6mm/yr, creating an ever increasing water depth. This is beneficial for shipping and navigation in the channel, which would not require dredging of the aggradated material. However, the reduction in bankfull volume with rising water levels is dangerous for flood control.

The effects of climate change are felt all around the world. An increased sea level goes hand in hand with an increased risk of flooding. To combat this, the coastlines must be reinforced to withstand future sea levels. However, repeatedly reinforcing coastlines to keep up with the sea level rise (SLR) could prove extremely costly. An alternative approach would be to shorten the coastline, as the Netherlands did with the Afsluitdijk to enclose the IJsselmeer. Looking at Europe, Groeskamp and Kjellsson (2020) proposed the construction of the Northern European Enclosure Dam (NEED) — a dam that would disconnect the North and Baltic Seas from the Atlantic Ocean. In this way, it would protect fifteen northern European countries against the accelerated global mean SLR (GMSLR), as it simultaneously shortens the coastline that requires reinforcement. This thesis aims to determine whether the NEED (Adaptation Strategy 2) would be a financially favourable adaptation strategy over raising the coastal defences on a country-by-country basis (Adaptation Strategy 1) around the North Sea to combat future GMSLR, and if so, at which GMSLR.

Through the use of the GLOFRIS model framework it was possible to estimate that by 2080 a total of 15,000 km2 would be inundated, affecting 9.5 million people and resulting in damages up to 1 trillion € for all fifteen countries combined. Reinforcing the regional flood protections (Adaptation Strategy 1) is estimated to have a total cost range of 245 to 335 billion € for a 1-metre GMSLR with an increase in costs between 170 and 235 billion € per metre GMSLR. The construction of the NEED (Adaptation Strategy 2), using an earth-fill dam design with 1:6 slopes on either sides, is estimated to be just under 1.1 trillion €, with an increase in costs of 11 billion € per metre GMSLR.

It was found that the NEED flood protection adaptation strategy will eventually become more financially favourable over the regional strategy. Estimated to be more cost-effective beyond 5.15 metres GMSLR, which is associates with construction costs of roughly 1.15 trillion €. This GMSLR for scenario SSP5-RCP8.5 is expected to occur between 2280 and 2660, approximately. However, as the total costs are greatly contingent upon the core material, modifying slope angles of the NEED design will lead to a significant reduction in volume and, hence, costs. For the alternative designs with a 1:4 and 1:5 slope, the total costs are reduced by 17% and 34%, respectively. For these designs, the NEED will already become favourable at 3.35 and 4.25 metres GMSLR, respectively.

Several cost distributions have been created based on the four aspects that have been investigated, namely (i) coastline reinforcement length, (ii) size of inundated area, (iii) population exposed and (iv) economic damages caused by flooding. Together with the extrapolated regional costs per country, it is possible to determine which distribution is the most and least financially favourable for each country and whether contributing to the NEED is even favourable at all from the perspective of each country.

This research scrutinised the costs, effects and consequences of the most extreme scenario that generated the greatest exposure indicator values (i.e. SSP5-RCP8.5 combined with a return period of 1000 years). Through this
assessment, it was possible to estimate the costs associated with both adaptation strategies, and furthermore, to determine at which GMSLR one strategy surpasses the other in financial attractiveness and when this GMSLR can be expected. However, it should be noted that recent studies have shown that, in reality, the most extreme scenario might, unfortunately, turn out to be even more extreme than the most extreme scenario assumed in this thesis. And as the consequences strongly dependent on how climate change will unfold in the future, the costs to combat and the timing of such GMSLR occuring will differ.

The results retrieved from this research provide insight into when the NEED flood protection adaptation strategy will become a better alternative to regional flood protection reinforcement. However, it should be borne in mind that it is not a matter of ‘either-or’, but rather ‘both-and’, as regional dike reinforcement cannot entirely be omitted when deciding to construct the NEED. Instead, a balance must be found in the extent to which regional dike reinforcement is required to protect the countries while the NEED is under construction. So there are plenty of uncertainties and questions that require additional research to fully comprehend all the effects of this massive operation and making it feasible.

In the context of climate change and urbanization, sustainable urban drainage systems (SUDS) are widely adopted measures to manage stormwater in the city on-site. However, their performance in practice often differs from modelled and laboratory-scale predictions due to the variability in properties of real sediments (in terms of size, shape, density and coagulation) compared to the silicate standard Millisil®W4. Clogging is a common source of failure. 
The SediSubstrator L is a decentralized stormwater treatment device installed as a pre-treatment step to mitigate clogging in a storage and infiltration system on the Rooseveltlaan in Amsterdam. It consists of a sedimentation pipe with a flow-separating grate, the SediPipe, and a filter-adsorbent, the SediSorp+. It is purported to remove 80 % of TSS by DiBT (the technical authority in the German construction sector) test principles that use Millisil®W4 to simulate real sediments. The full-scale unit was monitored in the city throughout May-September 2022 to assess its performance. 
The stormwater runoff discharged from the catchment had high concentrations of lead (54 μg/L) and zinc (790 μg/L), likely due to contact with gutters and old roofing material, amplified by the relative contribution of these roofs to the total catchment discharge (accounting for 50 % of the area contributing to runoff). The sediment (TSS) concentration was low, equivalent to 20 mg/L on average. The sediments were also light and fine—with an organic fraction of 66 % and with 78 % of diameter smaller than 63 μm.
In the SediSubstrator L, the TSS removal efficiency was 34 % on average. This corresponds to an estimated caught load of 2.7 kg for this period. The removal efficiency was shown to increase with an increasing stormwater TSS concentration, with longer antecedent dry periods and with lower TSS organic fractions. Turbidity dynamics in the system suggest that while a net sequestration of solids occurs in the SediPipe, there is a resuspension of fine solids. This was observed in a camera inspection to occur from solids which settle on or near the grate. In an extreme rainfall event on September 28th 2022, water collected on the section of the street connected to the SediSubstrator, the cause of which is still subject to speculation. The observed SediSorp+ filter resistance across the summer was not indicative of gradual clogging, but an inspection showed signs of decayed organic matter throughout the full length of the filter bedas well as traces of cement in two of the four cartridges. It is possible that these two effects together with turbulent inflows prompted the acute clogging behavior.

There is interest in using the SediSubstrator beyond the city of Amsterdam to reduce phosphorus loadings in the road runoff discharged to sensitive nature areas. On the Rooseveltlaan, the average total phosphorus removal efficiency was 18 % (50 % for dissolved, readily bioavailable ortho-phosphate). Interactions with settled sediments generated ortho-phosphate in the SediPipe, and fine particulate and colloidal organic phosphorus was shown remobilized in both the SediPipe and SediSorp+. The removal of ortho-phosphate in theSediSorp+ in natural rainfall was good (on average 50 %) and was shown to be consistent at different contact times (approximately 10-30 minutes). 
The installed unit should be monitored over a longer time period of two years for statistical significance and to capture seasonal variation in loads. Nevertheless, the removal efficiency observed on site is consistent with the results of a sedimentation model developed according to Ferguson & Church (2004), using a stormwater sediment particle density as measured at another location in the city. Design adaptations are recommended to improve the SediSubstrator L to the conditions observed in Amsterdam: namely, better site selection, a longer SediPipe section (24 m) and a second filter stage to better capture the fine suspended solids.

Sea level variations and storm surges are expected to increase as a result of climate change. 570 cities and some 800 million people are by 2050 estimated to be exposed to these phenomena when emissions do not decrease (UCCRN, 2018). It is, however, deeply uncertain if and to what extent emissions will decrease. Additionally, the effects of climate change are not fully understood due to its complexity, resulting in a wide range of uncertainty. Flood risk measures can be implemented to reduce flood risk. The economic evaluation of such measures is affected by other factors of uncertain nature such as economic growth. The Dynamic Adaptive Policy Pathways (DAPP) approach has been identified as an approach capable of identifying and implementing effective flood risk strategies under uncertain conditions (Haasnoot et al., 2013). This approach aims to provide decision-makers with insight into what action to take when. Simultaneously, the approach focuses on ensuring flexibility which facilitates adjustments to unforeseen conditions. Within this approach, so-called adaptation pathways need to be developed. These pathways describe a sequence of actions over time required to ensure a minimum level of flood safety. The DAPP approach has been applied to simplified cases in previous research, but not yet to more detailed master-planning for which the creation and economic evaluation of pathways is a not straightforward process. This results in the main research question of this thesis:

How can the Dynamic Adaptive Policy Pathways (DAPP) approach be used to create and select effective flood risk strategies under highly uncertain conditions?

This research question has been addressed by developing a framework capable of creating adaptation pathways and evaluating them with an incorporated scenario-based economic evaluation. This framework is supplemented with a probabilistic assessment that evaluates the performance of pathways in the full range of possible but uncertain futures. The use of these tools has afterwards been validated by applying them to a fictive case and a case study along the South East Coast of Singapore. The framework can be used to assess the sensitivity of uncertainties. Additionally, it can be used to obtain the conditions for which a different pathway turns out to be more effective. Damages corresponding to certain water levels are required as input and are used to build the damage function of a specific project area. These damages can be modelled with damage modules like the Global Flood Risk Tool (GFRT). The damage function and other basic information like dimensions and characteristics of the project area are used to perform an economic optimisation of individual measures. A selection of adaptation pathways (consisting of combinations of measures over time) is made based on prerequisites and a scenario-based evaluation. The scenario-based evaluation is supplemented with a probabilistic assessment as the use of scenarios might lead to cognitive biases and does not cover the full range of future possibilities (Hoffmann, 2017). This probabilistic assessment is conducted by means of a Monte Carlo simulation and can be used to evaluate the robustness of pathways in the full range of possible futures. A pathway can afterwards be selected and trigger values that should initiate the implementation of subsequent measures can be obtained via the framework.

The developed method has first been applied to a fictive case. A small area with a standard damage function was assumed for this. After the framework had been validated, the input-conditions were altered to assess the individual influence of each uncertain input value. The outcome turned out to be dependent on the characteristics of the project area and the assumed conditions. An increased area resulted in a pathway with a flood wall instead of a landfill as first measure being most effective. Out of the uncertainties, the discount rate and socio-economic growth rate turned out to most significantly affect the Net Present Value (NPV) and Cost-Benefit Ratio (CBR) of flood risk strategies. Especially, low discount rates and high socio-economic growth rates resulted in pathways built up of individual measures with lifetimes exceeding the technical lifetime of measures. To prevent this, and to ensure a flexible approach, the lifetimes of individual measures were restricted. A flexible approach enables one to adjust to conditions other than those that have been assumed. Measures with a long lifetime ahead lead to bigger investment costs and these are irreversible when the conditions turn out to be less severe than anticipated. The contrary also turned out to be possible. These short lifetimes corresponding to measures with practically infeasible low heights were prevented by setting a minimum height at which the linear relationship between the height and costs of measures starts. The probabilistic assessment was conducted after a pathway was selected. Increasing the range of uncertainty for this pathway logically led to a wider range of possible outcomes. This wider range of outcomes can be a reason not to select a certain pathway as the probability of a low NPV is higher. The fact that this difference could not be observed in the outcome of the framework underlines the need for this probabilistic assessment. Finally, trigger values were set for the selected pathway of the fictive case. The trigger values were initially set for the planned subsequent measures. However, it could be observed that the obtained trigger value for the planned subsequent flood wall increment did not result in sufficient time to implement a storm surge barrier without dropping below the required minimum level of flood safety. Therefore, trigger values corresponding to the next planned subsequent measure could potentially lead to the exclusion of other possible subsequent measures. Instead of setting trigger values for the planned subsequent measures, trigger values should provide enough time for all possible subsequent measures to forestall the exclusion of possible measures and ensure flexibility.

The findings from the fictive case led to adjustments of the framework to ensure practical feasibility and flexibility. The adjusted framework was afterwards applied to a real-life case along the South East Coast of Singapore characterised by a narrow water level distribution, i.e. a relatively small difference (∼15 centimeters) between water levels that differ a factor of 10 in return period. A storm surge barrier turned out to be a factor of 10 more costly than alternative solutions, irrespective of the assumed sea level rise scenario. Therefore, it was concluded that the storm surge barrier was not the desired flood risk reduction measure for the project area and the area was subdivided into smaller areas to further optimise the flood risk reduction strategy. The framework was used to create flood risk reduction strategies. No measures turned out to be required until 2092 for the assumed conditions. The sensitivity analysis of this case study showed that assuming a more severe sea level rise scenario (an additional 58 centimeters in 2100) and accounting for additional storm surge caused by climate change, could result in measures being required over 50 years earlier. Without taking this into account, two pathways turned out to satisfy the safety standards until 2200 for the assumed conditions. One pathway solely consists of a flood wall and subsequently flood wall increments (AP10) while dryproofing is the first measure of the other pathway and subsequently a flood wall and a flood wall increment are implemented (AP33). The costs of AP10 turned out to be slightly higher in the full range of futures than that of AP33 but the probability of obtaining a higher NPV than obtained from the framework was also higher (58% vs. 51% of the outcomes higher than the NPV of AP10 obtained in the framework). As the differences between the probabilistic assessments of the pathways are not substantial, the preferences of local stakeholders are even more important. Dryproofing can lead to inundation of the land for high water events with a return period lower than the safety standard while Singapore has set the goal to protect its coastlines and prevent inundation of the land. Therefore, the pathway consisting of a flood wall and flood wall increments turns out to be the most suitable solution for the project area.

This research contributes to the existing knowledge related to the DAPP approach as it smooths the not straightforward process of creating and evaluating adaptation pathways under uncertain conditions. It showed how to economically optimise individual flood risk reduction measures and build adaptation pathways out of those measures. A framework has been developed to automate this process and instantly evaluate the effectiveness of such pathways for set conditions. This study also showed how a probabilistic assessment of these adaptation pathways could be used to select a robust flood risk strategy. This developed method can further be fine-tuned by including transfer costs that reflect the costs of maintaining flexibility in the face of deep uncertainty. Additionally, flexibility can be incorporated within the probabilistic assessment to enable alteration of type and/or height of subsequent measures for conditions different than assumed. This would result in a more accurate assessment. Automating the integration of the probabilistic assessment within the framework can eventually lead to one complete tool which enhances the applicability and allows for the probabilistic assessment of all pathways instead of just a selection of pathways.

The research presented in this document presents a comparative analysis of the mainstreaming process of Sustainable Urban Drainage Systems (SuDS) in mid-sized and large municipalities in the Netherlands. As a result of the extreme weather conditions presented by the STOWA, deteriorating sewers, and the increase of paved areas in urban environments, alternative solutions (i.e. SuDS) are becoming more relevant. However, the adoption of these innovations is still rather slow. Answers are sought by different scholars, however, for the Netherlands research remains limited. SuDS that are implemented in public space fall under the responsibility of the municipalities. Hence, recent studies have highlighted factors in the implementation process of SuDS for municipalities in general. The biggest municipalities seem to always be leading in research and disparities in how different organizations perceive influencing factors of the implementation process have not been studied yet.
The research objective of this thesis is to find to which extent the perceived factors in the main- streaming process between different sized municipalities differ.

The methodology consists of a literature review, two case studies, and a focus group. The literature review concerned transition theory which was applied to climate adaptation. A conceptual framework has been developed that describes the mainstreaming process. Different theories were combined in this framework: the Mainstreaming model, four-A framework, Governance Capacity Framework, multi-level perspective.

The empirical research applied consists of case studies that have taken place in two Dutch municipalities: Rotterdam and Capelle aan den IJssel. The case studies considered were projects that implemented a new concept for the first time. The main criteria for the selection were the size of the municipalities and their (geo)hydrological boundary conditions. A comparison was made between the results of both studies and cross-checked in a focus group. The data in the case studies were collected through semi-structured interviews and documentation. The semi-structured interviews were based on themes identified in the conceptual framework. The semi-structured interviews were conducted via Microsoft Teams. Examples of questions that were asked were: "What were the main drivers for the project in your city?" and "Do you find that propositions of innovations are well received in your department?".
The interviewees were part of these case studies and sampled through a stakeholder diagram and snowball effects. In total 10 participants were interviewed which were part of the case studies. To increase the validation of the case study results, different municipalities were invited to participate in a focus group to evaluate how they identified with the findings. This focus group consisted out

The findings of the study imply that the mid-sized municipalities differ from larger municipalities mainly on three factors:
• They still have to form climate adaptive strategies
• Their allocated budgets are inferior
• They lack policies that allow for alternative methods as opposed to traditional sewer management
• They lack climate-adaptive experts who are actively involved in projects

Furthermore, it was found that knowledge sharing of pilot experiments should be pursued more actively to facilitate the adoption of SuDS. In addition, this knowledge is now mostly catered to engineers, developers, and policymakers. For which it was found that to facilitate adoption, the involvement of asset managers should be pursued too.

The research is of conceptual use and is of use for multiple groups. The problem statement has been initiated by VPdelta which is a valorization program that bridges innovative SuDS to the market. It is therefore interesting for them to gain insights into the barriers and driving factors on the side of the clients. For scholars, the research gap of heterogeneity between municipalities has been explored which helps to understand the problem from different perspectives. Lastly, it may be interesting for mid-sized municipalities as recommendations are formed for what they can do to become more climate adaptive.

In the Netherlands, the frequency and severity of extreme rainfall events are expected to increase. This can result in severely detrimental effects. It is complicated for municipal actors to effectively manage these events, as it requires judgement on probabilities, costs, and uncertain impacts. As a result, obtaining scientific knowledge through climate tools and model results has become increasingly important in informing policy-making processes. While model results and climate tools have been shown to create an imperative to act for municipal actors, a clarification of how a certain approach might offer support in a specific context is scarce. By simplifying model simulations for municipal actors, information gets lost and becomes (unconsciously) framed, leaving room for the personal interpretation of municipal actors. Framing can change the actor’s perception without altering the scientific information they were initially provided, which might result in different decisions taken on water management. Decision-making is not an individual process. It involves interaction between a multitude of stakeholders of various disciplines, all with own individual contextual factors. It is essential for effective decision-making on extreme rainfall events that interaction is well-coordinated.

This integrated master thesis for the master’s degrees in International Land and Water Management and Communication Design for Innovation, therefore, aims to explore the influence of visually framed extreme rainfall model results on the interaction between municipal actors. This is explored in the Municipality of The Hague and the Huygenspark neighbourhood. The model results have been adjusted to two contrasting frames: in terms of gains or losses and psychological distant or near impacts.

These two contrasting frames have resulted in the development of four visually-framed extreme rainfall model results, hereafter named maps. For the distant loss map, water nuisance has been assessed in the Tygron Geodesign Platform. The water nuisance map shows that especially the Stationsweg, the tunnel at the Rijswijkseweg, and the tunnel underneath the train tracks will have water nuisance issues during extreme rainfall events. For the near loss map, the framing of adaptation tipping points has been applied. Adaptation tipping points frame the issue from the socio-political objectives and show the moments in time at which a change in the current management strategy no longer meets the municipal actors’ objectives. The socio-political objective has been identified to focus on maintaining the accessibility of roads for cars and ambulances. The model shows that the Stationsweg and the tram tunnel cross this threshold during a once a 25 years rain shower (40 mm/hour), while the Rijswijkseweg tunnel reaches the threshold already at a rain shower of less than once a 10 years (30 mm/hour). This return period will become more frequent to once every 13 years and an unspecified low non-extreme return period in the upper scenario of 2050 respectively. The two main chances to tackle this issue are either spatially, in the Oranjeplein and Huijgenspark or through adaptation mainstreaming opportunities.

The four maps were interpreted by fourteen municipal actors within the Municipality of The Hague through semi-structured interviews. Visual framing was found to have a profound effect on the interpretation of municipal actors. The near-framed adaptation tipping points map made the issue more concrete and expressed urgency as well as the necessity to take action compared to the distant-framed water nuisance map. The chance maps created a more positive interpretation than the loss maps. Besides, the interpretation of maps was also determined by the pre-existing knowledge structures and ways of looking at the issue, resulting in three distinct interpretations for the adaptation tipping points map. While every map has its own main interpretation, most municipal actors emphasised that the maps should be combined to create an overall story. This story can be used during interaction to convince others, but it can also be to start a discussion or to weigh different options. The visual maps can, therefore, be seen as a ‘story support tool’ for interaction.

In the past decades, beach nourishments have been widely applied along the coast of the Netherlands. Different studies on beach nourishment have been conducted over the years. Most of these studies regard the design, execution method, morpho- and hydrodynamic behaviour, and ecological impact. However, the relationship between the design aspects and the longevity of beach nourishment is not well understood. Here we show with the multiple linear regression (MLR) model that the design aspects volume per metre, height and length of beach nourishment are of interest to analyse the relationship with beach nourishment longevity in the central Holland coast. The storm variables were negligible according to the model since the regression coefficients are insignificant. After numerous reruns of the MLR model, it was noticed that the regression coefficient of design volume per metre is fluctuating. This could indicate a positive, negative, or even no distinct correlation between the design volume per metre and longevity. Therefore, no clear conclusions could be drawn on the design of nourishment volume per metre in order to extend a longer beach nourishment longevity. According to the MLR model, the design length has a positive regression coefficient and design height a negative regression coefficient. These signs suggest that a lower design height elevation and longer design length will result in a longer beach nourishment longevity. The computed beach nourishment longevities of the 7 locations (Julianadorp, Callants-oog, Bergen aan Zee, Egmond aan Zee, Bloemendaal aan Zee, Scheveningen, and Ter Heijde) along the central Holland coast showed that the average longevity of each location could not be interpreted with certainty. This outcome results from the given confidence level of the longevities and the number of beach nourishments used for the computation. Nevertheless, these computed longevities showed that a typical beach nourishment longevity along the central Holland coast is in the range of 3 and 3.5 years. Further, it was observed that computed beach nourishment longevities along the central Holland coast have increased between 1990 and 2020. The increase of beach nourishment longevity coincided with a policy shift in 1999 when shoreface nourishment became a common practice. Therefore, this data suggests that the presence of shoreface nourishment had a positive impact on the longevity of beach nourishments. Despite this result, no certain conclusion could be drawn as the positive contribution can also be caused by increasing nourishment volume through the years. Overall, data-driven research forms the basis of this study and provides a first qualitative insight into the relationship between design aspects and beach nourishment longevity of the central Holland coast.

Myanmar lacks a water quality monitoring system to monitor changes in water quality in the Ayeyarwady Basin. This study aims to find to what extent changes in water quality can be measured in the Ayeyarwady basin and to identify requirements for a water quality monitoring system. In this study, the current water quality monitoring systems of the Ayeyarwady, Mekong, Chao Phraya and Hong (Red) River Basins were compared. Several contamination sources were used to identify contamination scenarios. A river model of the Ayeyarwady and its main tributary, the Chindwin, was made to understand the workings of the river system and the distribution of contaminants throughout the Basin after contamination events. This study found that contamination is diluted to a high degree over long distances in the Ayeyarwady Basin. At low river discharge, the remaining contamination peak downstream of large contamination events like waste water treatment plant failure or tailings dam failures occurring upstream in the river near the limits of detection. During high river discharge these concentrations can be over 17 times smaller. The study showed that in case of pulse water quality incidents for most common water quality parameters, the monitoring system should have a temporal frequency of once per week with an analytical accuracy of around 0.1 microgram/l. A high-quality monitoring station is required in both river branches just upstream of the confluence of the Ayeyarwady and Chindwin rivers as significant dilution occurs here. Finally, it is crucial to clearly define and distribute measurement responsibility.

The aim of this thesis was to investigate the evolution of Ilissos and Kifissos river basins in Athens, Greece and the ways this evolution was influenced by specific human factors. The dynamics of the human-water interactions have been studied in the frame of sociohydrology and the central key was to study the impact society had on the hydrological regime of the rivers and the rivers on society, at the basins of Ilissos and Kifissos. Athens is the capital city of Greece, where almost half of the country’s population is located and the most important financial center of the country, where about 70% of country’s financial activity takes place. The time frame of this thesis covers almost the last 200 years, from 1834, when Athens became the capital city of Greece, until 2019 and takes into account the most important political and social events of these years. The human factors used in this research and which have also been used in sociohydrological studies are the community’s sensitivity and memory, along with human parameters like the social and political regime. In this research, the case study research method was selected for exploring in depth the interventions applied at the two rivers and the relations of people with water resources during the study period, by paying attention at details and attempting to correlate conditions and events. In more details, for collecting information about the evolution of social and political regime and the interventions to the rivers, the historical analysis method was used and for exploring the evolution of community’s sensitivity and memory, the method of content analysis at newspaper articles and municipal acts was chosen. The study showed that according to the way the community’s sensitivity evolved, there has been a change at the way people face Ilissos and Kifissos, from economically exploiting the rivers, towards a more environmentally sustainable management attitude. However, throughout city’s political and social history there have been periods, where the prevailing way people faced the two rivers changed drastically due to severe political and social events like wars, change of political regime and severe flood events. Moreover, the memory of the rivers influenced the way people treat the rivers, since it was found that there had been positive and negative memories related to the rivers, concerning their historical value on Athens history, memories related to their good or bad environmental condition and memories related to flood events. Usually, memory mentions were used to criticize the government for the process of projects or were used as motivation for more protection measures.