Due to the rising sea level in combination with land subsidence there is a need to reinforce the dikes. The use of a crest element to increase the height of the dike is an effective and relatively cheap way to reinforce the dikes (Hogeveen, 2021). When a crest element is used, the jet generated by wave breaking on the dike slope impacts on the crest element, leading to an upward spraying motion of the water. This upward sprayed water can potentially be transported by the wind over the crest element and therefore contribute to the wave overtopping discharge. Small scale physical model tests were performed on a smooth dike slope of 1:6 to gain more knowledge about this influence of the wind on wave overtopping. Studying the influence of the height of the crest element, a promenade in front of the crest element and the slope of the dike was part of the research.

The Netherlands is world famous when it comes to coastal defence. The world is always changing, therefore the Netherlands, together with many countries, has to adapt constantly to the climate. This constant change means that in particular the coastline of the Netherlands requires extra attention because of the uncertainty of sea level rise. The Dutch coastline is protected by means of a static approach. However the intention for the future is to apply an adaptable design to better handle sea level rise. This report focuses on a method that uses a dynamic approach with the aim of keeping the Netherlands protected against rising sea levels that are uncertain. This dynamic approach consist of several pathways that each consist of different actions. With the help of evaluation-criteria, the pathways in the dynamic approach are evaluated. The outcome of this evaluation is described and recommendations for future research are given.

The report focuses on keeping the coastline of the south-west of the Netherlands protected against the uncertainty of the rising sea. This will be done with the help of a dynamic approach. First, an area analysis was carried out to find out what aspects should be given the most attention. After that, the method of DAPP is used to function as a dynamic approach. This Dynamic Adaptive Pathway Policy is then used to implement the different pathways in a structured way. These pathways are made up of different actions. These actions are existing plans presented by Deltares and they form a big list. Not all plans do function properly in order to function as a flood protection and so a selection method is used to extract the right plans out of this list. The requirements that are used to select the right plans have its main focus on protecting the hinterland against sea level rise, storm surge and wave load. The extracted plans that function as an action are implemented in the different pathways of the DAPP. To evaluate these pathways, evaluation-criteria are used in a Multi Criteria Analysis. These criteria are extracted from sources like a stakeholder analysis, old and new watermasters and a brainstorm session with the group members who act through their own accumulated expertise. The extracted criteria in combination with determined weighting factors are placed in a Multi Criteria Analysis after which the pathways have been assessed individually. This evaluation process led to some pathways being iterated to a different shape for the final design of the DAPP.

From the project can be concluded that the DAPP approach works well to combine different static plans into a comprehensive mitigation strategy. Secondly the evaluation criteria can be successfully derived from the old and new watermasters. The old watermasters already have one or more of their plans implemented. The new watermasters, are working on flood protection plans for the future in their daily life and have a lot of experience in the current engineering field. From the stakeholder analyses, the criteria can also be derived but than from the perspective of a variety of stakeholders. Thirdly, organizing criteria using a PESTLE (Political, Economic, Social, Technological, Environmental) and objectives tree has significant benefits for determining weighting factors. At last, it can be concluded that the main requirements used in this project are a good starting point, but they are only focused on reducing the flood risk (only technology). To select plans on a wider perspective(also Political, Economic, Social, Legal and Environmental), it is recommended to take a closer look to requirements from that perspectives. Advised is to consult experts in those fields to help with that.