Porous asphalt roads are renowned for their improvements of driver safety. Their high content of interconnected voids allows for an easy infiltration of water in the asphalt layer. This property limits the volume of standing water on the asphalt, reducing the risk of aquaplaning and increasing driver visibility by limiting the splash and spray effect. Other advantages include noise reduction and filtering of the pollutants of runoff water. As such, the use of porous asphalt has become more common across the world in the past 50 years. Currently about 90%-95% of Dutch highways is constructed using a toplayer of porous asphalt or Zeer Open Asfalt Beton (ZOAB) according to Dutch nomenclature.

While porous asphalt is known for its improved hydraulic performance, very little is known about the runoff response from its application on the highway. Rijkswaterstaat, the Dutch government agency responsible for managing the countries highway, always used a percentage of 20%-40% of precipitation
that will occur as runoff in internal documentation. However, these values need to be verified over a prolonged period of time using a continuous timeseries of recorded runoff. Secondly, in recent years the objective of Rijkswaterstaat has become to infiltrate as much runoff as possible in the verge next to the road in order to save costs in construction and maintenance of sewage as well as decrease the burden of the pollutants and peak discharge on the local environment. This has resulted in a need for a better understanding of the behaviour of precipitation on a porous asphalt highway under different conditions.

This study investigated the relation between the precipitation and the following runoff response on a 50-meter stretch of highway in the Netherlands. Furthermore, it explored the overall in-situ dynamics after a precipitation event. This was done through water balances and a multivariate analysis using a principal component analysis and a linear discriminant analysis. Finally, a linear reservoir model was applied to measured runoff responses.

Overall, this study has shown the potential of the linear reservoir model to accurately describe an in-situ runoff response. It has shown that this model is also applicable when there are multiple successive precipitation peaks during a single precipitation event. However, the total runoff volume during an event
can not yet be predicted. Furthermore, the water balances are not closing during the winter of 2024-2025. As such, a more thorough understanding of the evaporation dynamics on the highway is required at the relevant timescales. Lastly, this study has provided a statistical indication that traffic could play
a role in these dynamics as well. ... Read more

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

Climate change presents growing risks to urban areas through extreme precipitation, heat stress, and drought. Addressing these challenges requires not only targeted adaptation strategies but also a rethinking of how cities integrate multiple sustainability transitions. This thesis places climate adaptation at the center of five key urban transitions—energy, mobility, circular economy, environmental health, and nature inclusiveness—and explores their interrelations within the built environment. Using a grounded theory approach, the study combines a literature review with an exploratory multiple case study of Almere, Lelystad, and Urk—three municipalities in the Dutch province of Flevoland. The case study consists of three components: a policy study based on coding and analysis of 31 municipal policy documents, a project study analyzing three spatial redevelopment and three new development projects through qualitative analysis, and three supplementary interviews with municipal professionals. The policy analysis showed that municipalities pursue an integrated urban planning approach for climate adaptation, focusing on local water retention and blue-green infrastructure. This approach lays the foundation for emerging relations with other transitions.
Relations were categorized by a framework distinguishing geographical, physical, and project-based relations. Geographical relations concern the distribution of space, showing that the mobility transition can support climate adaptation by freeing space through reduced car infrastructure. Policies in all municipalities aim to reduce car use and promote active mobility, potentially opening up space for urban greening. Although this connection is not strongly emphasized in policy, redevelopment projects especially demonstrate its potential. Conversely, the energy transition competes for space, requiring extensive infrastructure. While policies call for spatial integration, project results are mixed. Some new developments coordinate both transitions, but in others the spatial demands of the energy transition compromise climate adaptation. Physical relations concern the shared use of infrastructure. Climate adaptation shows synergies with other transitions through green and blue-green infrastructure. It aligns with the environmental health transition, both relying on urban greening to promote a healthy environment. Policy documents highlight this overlap, with green spaces designed for recreation and health. Active mobility infrastructure also integrates with blue-green spaces, promoting aesthetics and micro-climates. Nature inclusiveness further supports climate adaptation by expanding green networks and ecosystems. While opportunities exist for integrating circular and energy transitions, practical applications like rainwater reuse and green roofs were not observed in projects. Successful integration relies on aligning stakeholder agendas in project-based collaboration. Although policy documents advocate for integration to reduce costs and disruption, interviewees noted that time pressure, limited expertise, and unclear priorities often limit implementation. Climate adaptation and urban greening were frequently treated as add-ons rather than core components. By clarifying the spatial-technical relations between climate adaptation and other transitions, this research contributes to a better understanding of how municipalities can navigate the complex demands of urban sustainability in practice. ... Read more

Urban areas increasingly face dual challenges of managing stormwater safely while reducing dependence on potable water for non-essential uses. Although decentralized rainwater harvesting is often promoted as a complementary strategy, the performance of ultrafiltration (UF) systems on real roof-harvested rainwater—particularly under different hydraulic driving forces—remains insufficiently characterized. In particular, few studies have directly compared gravity-driven membrane (GDM) and pressure-driven membrane (PDM) configurations using the same membrane material and the same variable-quality rainwater.

To address this gap, this study experimentally evaluated and compared a GDM and a PDM ultrafiltration system for on-site treatment of roof runoff at The Green Village (TU Delft). Both systems used identical 150 kDa PES flat-sheet membranes housed in Sepa CF modules. The GDM setup operated for 30 days under a constant hydrostatic pressure of 59 mbar, while the PDM system operated for 20 days under constant pump-driven pressure. The comparison aimed to quantify differences in flux evolution, operational stability, and water-quality improvements under realistic decentralized conditions.

The initial permeate flux in both systems was approximately 25 L/m²hr. In the GDM configuration, flux declined rapidly and stabilized at around 4 L/m²hr within five days, maintaining this value without cleaning or external energy input for the remainder of the 30 day run. In contrast, the PDM system exhibited a continuous decline from 23 to less than 1 L/m²hr in almost 20 days, with no sign of stabilization. Both systems reduced turbidity from an initial 1.4 NTU to below 0.4 NTU, while pH (6.9-7.5) and electrical conductivity (107-134 𝜇S/cm) remained largely unchanged, as expected for ultrafiltration. Microbiological analyses showed no detectable E. coli in any sample and total coliform concentrations above 2419.6 MPN/100 mL in the raw rainwater, indicating environmental—but not fecal—contamination of the feedwater.

These findings demonstrate that gravity-driven ultrafiltration can achieve stable, low-energy operation for decentralized rainwater treatment, whereas pressure-driven UF suffers from progressive fouling and declining performance under continuous operation. The work is novel in providing a controlled, side-by-side comparison of GDM and PDM systems using the same membrane and real roof-harvested rainwater, offering empirical insight into how operational mode influences fouling dynamics and long-term flux stability. ... Read more

Access to safe and reliable water is a fundamental human right, yet many rural communities in Nepal face persistent challenges in achieving water security. Women are disproportionately affected due to their primary role in household water management. Over the last decades there has been an increase in gendered studies on women's water burden. This study examined women’s perspectives on domestic water access and use in four villages within the Bardia National Park buffer zone in the Terai region of southwest Nepal. Most households rely on hand pumps for water, though some have intermittent tap water access. Using Q methodology, this research explored women’s perspectives on domestic water access and use using a set of 30 items. Principal Component Analysis (PCA) and varimax rotation resulted in a three-factor interpretation explaining 71\% of the study variance. The main findings were first of all that the importance of good drinking water quality was shared across factors, but that this did not lead consistently to the adoption of household water treatment (HWT). Second, piped water was envisioned for various uses, shaped by economic considerations and differing levels of concern about fluctuating water quality and seasonal scarcity. Lastly, community meetings played a central role to the adoption of water hygiene and HWT by only one factor, which suggests that their potential may be underutilized. ... Read more

Ghana runs the risk of becoming water insecure. As population growth increases, so does water demand, and climate change increases uncertainties in supply. There are furthermore many inequalities at play that significantly affect how Ghanaians access water. It has been established that good water governance can alleviate both water security and water equity issues. However, many solutions of good water governance revolve around centralized governance, while the Ghana government has reformed to a decentralized system in the 1990s. Local government is now responsible for water governance, but local government often lacks the capacity to manage access to water effectively. A good governance approach that could circumvent these issues is participatory governance, an approach that focusses on the inclusion of community members in decision-making processes.

Little research has been performed on the links between participatory governance and access to water. To fill this gap, this thesis has selected two case-studies. As peri-urban areas are often overlooked in research into access to water, two peri-urban areas that have undergone the implementation of a participatory governance approach were selected. The first is the peri-urban town of Dodowa, where a Transition Management approach was implemented focused on transitions in sustainable groundwater management and the inclusion of community members. The second is the peri-urban municipality of Ejisu-Juaben where the Community Ownership and Management approach was implemented.

The objective of this research is thus to uncover how participatory water governance influences access to water in the cases of Dodowa and Ejisu-Juaben, in Ghana. To achieve this, levels of access are measured along five measures: quality, accessibility, availability, affordability, and equity of access. Next to that, governance approaches are analysed and levels of participation of community members are determined. Two communities were selected in each peri-urban area where community representatives were interviewed, and interview surveys were performed with community members. The results from these interviews and surveys were supplemented with literature research.

Most significantly, the results show the complexity of the relation between governance and access to water. Access to water in and of itself is a complicated topic and so is governance. Different complex governance modes, successful and less successful participatory approaches, and complex configurations of access to water came to the forefront. The results furthermore showed that not only governance but also the presence of natural resources can be a determinant for good access to water. Next to that, for these cases intervention of government or non-government agencies played a large role in determining the success of the participatory approaches. One of the underlying reasons for this was the lack of financial resources available to communities and community representatives to provide access to water for their community.

Considering the complexity of the relation between access to water and water governance, this research recommends for future research to include more cases for comparison as the results from cases in this research on their own cannot be extended to other cases. It is also recommended to research specific context factors that may influence the link between governance and access, and to further research why governance approaches fail. Lastly it is recommended to do more extensive research into the development of a ladder of access that takes the use of multiple sources into account. ... 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

The knowledge deficit model assumes that people make more informed decisions when they are presented with more information. This model is often used in communication strategies while it has received quite some critique from science communicators and is not well supported by social science theories. One of these critiques comes from the observed Dunning-Kruger effect, where individuals unskilled in a certain area do not possess the skills to realize their incompetence. This effect has not been researched extensively yet in relation to climate change science communication and is the topic of this paper. By means of an online questionnaire (316 respondents), respondent’s knowledge and estimated knowledge on climate change is tested. The Dunning-Kruger effect has been detected for this group and suggests a critical re-evaluation of the knowledge deficit model, however additional research is necessary. An initial analysis into the influence of factors like age, gender and highest completed education level on actual and estimated scores and the discrepancy between these is also done to provide leads for further research. ... Read more

Most people of Malawi are dependent on rainfed agriculture for their livelihoods. This leaves them vulnerable to drought and changing rainfall patterns due to climate change. Over time, farmers have adopted local strategies and knowledge that help reducing the overall vulnerability to climate variability shocks. One other option to increase the resilience of rainfed farmers to drought, is providing forecast information on the upcoming rainfall season. Forecast information has the potential to inform farmers in their decisions surrounding agricultural strategies. However, significant challenges remain in the provision of forecast information. Often, the forecast information is not tailored to farmers, resulting in limited uptake of forecast information into their agricultural decision-making. Therefore, this study explores whether drought forecast information can be linked to existing farmers strategies and local knowledge on predicting future rainfall patterns. During a period of three months in Malawi, participatory research approaches are used to create an understanding of what requirements drought forecast information should meet to effectively inform farmers in their decision-making. Consequently, a sequential threshold model was established that relates annually monitored meteorological indicators before the rainy season, to the occurrence of dry conditions during the season. Dry conditions were expressed in the drought indicators that farmers require for their agricultural decision-making. Additionally, using interviews among stakeholders and a visualisation of the current information flow, further insights on the current drought information system were developed. Although farmers have their own strategies and timing of decision-making, this research has generalized some of the opinions and strategies to develop the ‘requirements’ which a contextualized forecast should meet. In August farmers require a prediction of the onset of the rainy season, typically starting mid-November. In addition, an update on the timing of the onset of rains is required in beginning of November. An overall indication of the ‘dryness’ of the rainy season is required in September. Here, ‘dryness’ is characterized by the number of dry spells, a composite ‘drought index’ of associated rainfall variables by the farmers. The forecast should be on a scale that is locally relevant (EPA level). This research consequently established a forecasting model, based on meteorological variables from local knowledge which can complement the forecast variables from the DCCMS. The results of forecast verification show that meteorological indicators based on local knowledge have a predictive value for forecasting drought indicators. Subsequently, skill analysis of forecasting incorporating all the above dimensions shows that the accuracy of the forecast differs per location with an increased skill to the Southern locations. In addition, it is also location dependent whether the contribution of wind, temperature or ENSO indicators gives the most predictive value. The results show that a combination of all indicators have the best predictive value. In addition, the results show that local knowledge indicators have an increased predictive value in forecasting the locally relevant critical events in comparison to the currently used ENSO-related indicators by the DCCMS. Additional research is needed to further analyse certain aspects of this research, such as research on the robustness of the model used. Research on the risk farmers are willing to take in their respective decisions could act as another requirement the forecast skill should meet. This highlights the importance of having continuous feedback from the farmers, since farmers may experience adverse impacts from wrongly informed decisions. Despite these limitations, it is argued that the inclusion of local knowledge in the current drought information system of Malawi may improve the provision of forecast information for farmers and shows that it is possible to capture local knowledge in a technical approach. The findings have relevant implications for other stakeholders, such as humanitarian and meteorological organisations, that are implementing drought-risk reduction approaches and climate services. ... Read more

In this thesis, the usage of scenarios for the participatory application of ADM is investigated in the context of the Paraná Delta, in Argentina. The focus is two-fold: (1) the research focuses on how a participatory design for ADM can be made, and (2) it focuses on which moment of the framework scenarios should be introduced in the participatory ADM ... Read more