Amsterdam staat voor uitdagingen door vaker voorkomende perioden van droogte zoals in het jaar 2018 en zware regenval tijdens de zomer, die verergerd worden door klimaatverandering. Om de schade te beperken, zijn als oplossing wadi’s ontworpen om regenwater van piekbuien op te vangen, vast te houden en te laten infiltreren in de bodem, en daarnaast spelen ze een belangrijke rol in het stedelijk waterbeheer. Dit onderzoek richt zich op de prestaties van wadi’s in stedelijk gebied Amsterdam tijdens toekomstige perioden van droogte, gebaseerd op de KNMI’23 klimaatscenario’s. Het doel van dit onderzoek is om te bepalen of stedelijke wadi’s, met hun kenmerken zoals een heterogene bodemopbouw, in staat zijn om voldoende bodemvocht, ook wel volumetrisch watergehalte, vast te houden om permanente schade aan vegetatie in de wadi te voorkomen. Hierdoor kan het ontwerp van de wadi zoals de bodemopbouw en de samenstelling van vegetatie, worden geoptimaliseerd zodat het ontwerp van wadi’s, klimaatadaptatief wordt.

In totaal zijn vier wadi’s, gelegen in Amsterdam Zuid en de Rivierenbuurt, gemodelleerd met behulp van het hydrologisch waterbalans model SWAP (Soil, Water, Atmosphere and Plant). De resultaten laten zien dat wadi’s met een specifieke bodemopbouw en diverse vegetatie samenstellingen, beter in staat zijn bodemvocht te behouden hoewel onder extreme droogteperioden het volumetrisch watergehalte in sommige gevallen onder kritieke waarden zoals het aanvulpunt (θt) zakt. Dit kan leiden tot permanente vegetatieschade, vooral bij oppervlakkig wortelende planten zoals natuurlijk gras.

Een gevoeligheidsanalyse heeft de invloed van bodemfysische parameters aangetoond, zoals het verzadigd vochtgehalte (θs) en de waterdoorlatendheid (Ks), en grondwaterstanden om de betrouwbaarheid van de resultaten te valideren. De analyse toont aan dat subtiele veranderingen in bodemparameters, zoals een hogere waterdoorlatendheid of veranderingen in grondwaterniveaus, een significante invloed hebben op het volumetrisch watergehalte (θv) in de bodem. Dit benadrukt het belang van het kalibreren en valideren van de modelresultaten in de werkelijkheid door middel van metingen op locatie.

Het onderzoek concludeert dat bij klimaatscenario ’2100Hd’ met referentie periode 2018, twee gemodelleerde wadi’s het volumetrisch watergehalte (θv) te lang ononderbroken onder het aanvulpunt (θt) komt, waardoor de vegetatietype: natuurlijk gras permanente schade door droogte zal oplopen. Daarentegen kunnen wadi’s een effectieve maatregel zijn tegen droogte, maar hun prestaties zijn sterk afhankelijk van ontwerpkeuzes. Het onderzoek benadrukt het belang van een klimaatadaptatief ontwerp, waarbij de resultaten van dit onderzoek richtinggevend kunnen zijn voor het optimaliseren van het ontwerp van wadi’s in toekomstige perioden van droogte.

Urban microclimates have a great impact on the thermal comfort of city inhabitants, with the Urban Heat Island (UHI) and the Subsurface Urban Heat Island (SUHI) effects posing a growing challenge under the accelerating impacts of climate change. This thesis focuses on investigating the UHI and SUHI effects and exploring potential mitigation strategies within a controlled urban environment, specifically the ”Heat Square” at The Green Village in the Delft University of Technology. The Heat Square serves as an experimental urban environment designed to analyse various urban cooling measures. To capture the spatial and temporal variations in soil temperature within the Heat Square, Distributed Temperature Sensing (DTS) technology was deployed. DTS measures high-resolution temperature data, which allows for detailed analysis of the soil temperature response to different cooling scenarios, including the implementation of green infrastructure, shading, and reflective surfaces. These in-situ measurements were then compared with urban microclimate modeling results using ENVI-met, a Computational Fluid Dynamics (CFD) tool for modeling urban microclimatic conditions. ENVI-met, along with other urban microclimate models, can predict the impact of urban design on local temperature and thermal comfort indices. The findings of this research highlight the significant potential of green infrastructure and shading as effective strategies to mitigate the UHI effect. Specifically, the introduction of vegetation and shading elements resulted in noticeable reductions in both surface and air temperatures as well as Mean Radiant Temperature (Tmrt) within the urban environment. These findings were supported by performing simulations of different urban scenarios of the Heat Square. However, the study also highlighted challenges in accurately modeling urban microclimates, as shown by discrepancies between the DTS measurements and ENVI-met simulations. These differences suggest the need for further refinement of model parameters to better approximate the complexities of real-world urban environments. Overall, this thesis contributes to the broader understanding of urban cooling measures and their role in enhancing the resilience of cities to climate change. The insights gained from this research are intended to inform urban planning and design practices, promoting the development of more sustainable and climate-resilient urban spaces as well as the applicability of urban microclimate monitoring tools. Future research should focus on refining the ENVI-met model of the Heat Square to enhance its accuracy in properly simulation real-life responses of the urban environment to climatic variations. Additionally, exploring a broader range of urban cooling strategies, including water-based solutions and varying surface materials, could broaden knowledge on heat mitigation strategies. Studying soil thermal responses in other urban environments with DTS would also be valuable for studying indirect effects of the SUHI effect. Collaborations between researchers, urban planners, and policymakers are important to ensure that scientific findings are translated into practical applications that increase climate adaptability of urban environments.

Urban stormwater management is put under pressure by increasing urbanisation and climate change leading to more frequent urban flooding. Such flooding can introduce ecological and public health issues by releasing contaminated water into the environment. Upgrading traditional grey infrastructure and implementing blue-green infrastructure (BGI) can be limited in their applicability for flood mitigation making Real-Time Control (RTC) an increasingly popular alternative due to its cost-effectiveness and potential performance benefits.
This thesis investigated the accuracy of rainfall forecasts and examined how forecast-informed RTC procedures could reduce flooding frequency and overflow depth while minimising negative side effects. The rainfall forecast accuracy was assessed based on three key properties: rainfall depth, forecast horizon, and mean forecast intensity. Using the insights from this assessment, three forecast-informed RTC procedures were designed to enhance the flood mitigation performance of a reactive RTC.
With perfect forecast data, flooding was completely prevented for two of the procedures, which used the longest but distinct horizons. The procedure using the shortest horizon was not able to prevent every flooding event due to the restriction in pre-emptive water release ahead of the forecasted rainfall events. The forecast accuracy analysis showed that the accuracy declined with increasing rainfall depth and lengthening horizon. Furthermore, the results indicated a shift from underestimation to overestimation of the rainfall depth as the mean forecast intensity increased. Applying the real forecast data, all designed forecast-informed procedures demonstrated reduction in total overflow depth of up to 70%, with the reduction linked to pump operation. However, the flood mitigation performance did not align with the expected results based on forecast accuracy, indicating that the procedures’ logic and implementation played a significant role in determining their effectiveness.
The findings highlight the trade-offs inherent in using forecast-informed RTC procedures, particularly the balance between the uncertainties of longer forecast horizons and the need for sufficient lead time to take preventive action. By addressing these challenges, this thesis provides practical insights to inform the design and implementation of advanced RTC systems, marking a critical step toward more sustainable and resilient urban water management.

Driven by global temperature increase and changing precipitation patterns, the intensifying hydrological cycle is expected to introduce more frequent and severe streamflow droughts. These changes will have a profound impact on agriculture, ecosystems and water management. This study analysed the spatial and temporal changes in streamflow droughts across 386 Mediterranean river basin from 1970 to 2019, focusing on their drought characteristics: duration, severity, intensity, maximum deficit, inter-arrival time, recovery rate and decline rate. The river basins were categorized into seven climatic regimes, and each was analysed for changes in these drought characteristics. Streamflow droughts were quantified
using the Threshold Level Method, defining drought events as periods in which daily streamflow is below a set threshold. To identify patterns, trends were assessed across four fixed time periods, along with multi-temporal analyses for both annual and seasonal changes. The analysis showed that annual streamflow droughts, although becoming longer, are getting slightly less severe and intense across the majority of river basins. However, distinct seasonal and regional variations were found. Between 1988 and 2019, winter and spring streamflow droughts experienced a decrease in duration and severity (up to -30% for winter) across the entire study area. On the other hand, regional differences were observed for summer and fall. During this same time period, summer and fall streamflow droughts in the Pyrenees, Southern France, Italy and Croatia have become much longer, more severe and more intense (20-40% for summer), whereas Central and Southern Spain experienced decreasing duration and drought deficit volumes. The implications of increasing streamflow drought conditions on the water availability in Mediterranean river basins is severe, which highlights the need for better understanding and water management of streamflow droughts.

Understanding wind profiles in urban areas is vital for various applications including urban planning and environmental science. This study aims to characterise the modification of wind profiles in The Heat Square through anemometer observations, focusing on the influence of building morphology. Previous studies have endorsed methodologies that consider building height variability. Still, our results suggest that rule-of-thumb morphometric methods based on average building height offer closer anemometric estimates in this specific urban setting. Unfortunately, the lack of inertial sublayer (ISL) wind speed measurements constrains the generalizability of our findings. Additionally, sub-optimal anemometer installation height poses another limitation to the study. Despite these constraints, the results should serve as reasonable estimates for modelling efforts concerning heat flux and heat stress. The study strongly recommends further research to address existing limitations, aiming to generate more reliable field estimates, particularly for The Heat Square and The Green Village.