This research addresses the issue of rising soil temperatures, driven by climate change. As the Drinking Water Distribution System (DWDS) is located in the sub-surface, the drinking water temperature in the distribution mains attains this rising soil temperature. Because the temperature of drinking water is an important determinant of water quality, Dutch law mandates that drinking water temperature may not exceed 25 °C. This study assesses several measures, including their quantitative impact on soil temperature reduction, and consequently on drinking water temperature reduction. These measures center on modifying the ground coverage, as this measure can be implemented without excavation and disrupting existing infrastructure in the sub-surface. This includes different types of ground coverage (e.g. changing concrete tiles, which are the existing top layer type, to vegetation), and creating temporary shade or applying white paint to the existing coverage type. The effect of (re)locating pipes to a deeper level or in the shade are also considered. The effect at the depth of a distribution main is analysed, which is shallow (0.7 m) in Rotterdam, and 1 m depth in general in the Netherlands.
Measurements confirm the significant influence of the ground coverage, mainly impacting the soil temperature in vertical (in-depth) direction. A detailed analysis reveals the quantitative effectiveness of the considered measures, indicating substantial cooling potential by modifying the ground coverage. Replacing concrete tiles with vegetation (in sandy soil) results in the most cooling effect of all analysed measures. White paint on concrete tiles emerges as particularly effective in reducing the soil temperature at the current depth in Rotterdam (0.7 m), and is considered an easily executable measure to prevent exceedances of the 25 °C threshold, mainly in case of urgency. In general, modifying the top layer as measure is considered feasible. This is because it avoids the need for excavation, in contrast to the alternative measures of relocation to a deeper level or in the shade. Additionally, the study quantifies soil temperature through simulations. A comparative analysis between simulations conducted by the soil temperature model and measurements facilitates an examination of the anticipated progression and the predicted effect of measures by the model, allowing for the formulation of recommendations to enhance the model.
As the results indicate that modifications to the ground coverage can significantly contribute to cooling the soil, this can mitigate potential threats to drinking water quality. The study advocates an integrated approach to decision-making, which includes collaboration between municipalities, drinking water companies, and research institutes. This cooperative effort is essential for identifying and implementing the most suitable and effective measures to safeguard high-quality drinking water, both now and in the future.

This report provides a flood risk assessment of the Isiolo River Basin, in collaboration with Nelen & Schuurmans (3Di, FIS Tool) and Zephyr Consulting (SLAMDAM). This flood risk assessment includes a study of the current flood risk management in Kenya, and in the Isiolo River Basin in particular, because the need for proper flood management is urgent: various climate studies predict an increase in rainfall and an increase in flood risk as a result of the effects of climate change.

Current flood risk management is inadequate. Kenya has defined 21 flood-prone areas whereof one of them is Isiolo Town. Isiolo Town is located in the ENN basin which is, relatively, the most prone to the effects of climate change compared to the other basins. Furthermore, the ENN basin currently has the highest poverty rate and avoidance of further enlargement in poverty rate is important, so there is a need to mitigate flood risks. Since Isiolo Town is located in the Isiolo River Basin, this basin has been chosen for an in-depth study.

The Isiolo River Basin is an Arid Semi-Arid Land region which is often prone to flash floods. Isiolo Town is a flat area located downstream of mountainous area, the rain which falls upstream flows fast downstream and converges into town, often resulting in inundation. Many hazards, both natural and others, are increasing the flood risk in the basin and specifically Isiolo Town.

This flood risk demands flood risk mitigation measures. One possible measure is the SLAMDAM. The SLAMDAM is a movable water-filled flood-barrier. One dam has a length of 5 meters and a height of 1 meter and the dams can be connected to a desired length. The water stored in the dam can be used afterwards for irrigation or other uses.
To recommend effective areas to implement the SLAMDAM, 3Di and the FIS Tool are used. 3Di is a hydrodynamic model and it creates flood maps for different rain events. These flood maps are used as input for the FIS Tool. The FIS Tool calculates the benefits for deploying the SLAMDAM at a certain location for a particular length. The locations which result in the highest benefit are recommended to deploy the SLAMDAM in case of particular rain events. However, a site visit is required to see whether the modelled situation aligns with the real-life situation and to see whether boundary conditions are met.
The SLAMDAM is also compared to other flood risk mitigation measures. Some were analysed using the FIS Tool, whereas others are evaluated based on five self-formulated ranking criteria. These criteria form the base of a scoring matrix where each relevant mitigation measure is scored on.

The performed research has shown the SLAMDAM to rank the best compared to other mitigation measures, both when using the scoring matrix and when using the FIS Tool. However, it is highly recommended to use the SLAMDAM in combination with a Flood Early Warning System. In this way the community downstream can be warned in time to deploy the SLAMDAM. The FIS Tool is found to be especially valuable in finding proper locations for deployment and the dam can be stored close to these locations, enabling fast deployment of the dam in case of need.