It is already acknowledged that Nature-based Solutions can be used to attenuate waves, however it is still uncertain to what extent the vegetation can contribute to decreasing the flood risk. So far mainly small-scale tests have been performed to quantify wave attenuating properties of vegetation. To quantify the effect of more extreme wave conditions (high-water levels and wave heights), full scale tests are required. In the Delta flume of Deltares large-scale physical model tests with a willow forest of 40 meters in front of a dike are conducted. Three different measuring methods: visual measurements, terrestrial laser scanning and video imaging, are used to quantify the wave run-up and wave-overtopping on the dike. This is the first time a ‘Machine Learning algorithm’ is used to obtain the wave run-up heights on a dike from video footages. It is also new that the wave overtopping volumes are determined by a laser scanner without using a wave overtopping tank, which was initially used to collect and measure the real overtopping volume. Results by the laser scanner show an overestimation of the overtopping discharges at high water level for higher crest freeboards, making these results less reliable. However, more research and a thorough validation are required to confirm the accuracy of this method. From results obtained by flume experiments can be concluded that remote sensing: laser scanner and video imaging, are accurate methods to measure the run-up on a dike. Thus, the camera in combination with Machine Learning is an accurate, simple and low-cost technique, to measure the wave run-up on a dike. Results from the camera not only give the run-up height, but also give new insights in the variations of the wave run-up over the dike. It can also be concluded that a willow forest of 40 meters causes a significant reduction in the wave run-up and overtopping, for both willows in summer and winter state. Further research is needed, so these significant reductions can be implemented in the design and assessment of dikes. The most commonly used models for designing a dike are the TAW (2002) and EurOtop. Comparing the obtained results, show that the determined wave run-up from the experiments are underestimated by the TAW (2002). The TAW is an empirical formula, based on a large data set of mainly small-scale experiments. Therefore, the difference between the test results and the TAW could likely be attributed to scale effects. However, more measurements at full scale are needed to confirm this.

The Weg naar Zee (WnZ) region of Suriname’s capital Paramaribo is dealing with coastal erosion. Images from the past 30 years have shown coastal retreats of up to 1.3 km. Mangrove forest used to be present in large numbers at the location. These forests enhance accretion, but due to different reasons, the number of mangroves has decreased significantly. Several attempts have been made to rehabilitate the mangrove at WnZ. Sediment Trapping Units (STUs) have been constructed, with the purpose to enhance accretion and thereby create ideal conditions for mangrove development. The units consist of walaba poles with bamboo as filling material. Walaba is a suitable wood type for this and also grows in Suriname. From bed level change results, field observations and interviews it could be concluded that there is room for improvement. Therefore, the following project goal was formulated: ‘To present methods for mangrove rehabilitation at the WnZ coast, which can be supported by the key stakeholders’. To present mangrove rehabilitation methods, it was necessary to gain insight regarding the WnZ stakeholders’ involvement when it comes to coastal management. Fourteen key stakeholders were identified and analyzed. To gain even more insight into the views, perceptions and wishes of the WnZ region’s inhabitants, a survey was also conducted. Knowing the success factors and design requirements resulted in the analysis of which mangrove rehabilitation designs are applicable and supported by the region’s stakeholders. The first step was conducting a Multi-Criteria Analysis (MCA) in which five alternatives are weighed. From this analysis the top three variants were chosen as preliminary designs: 1) Adapted STU, 2) STU with Nourishment and 3) STU with chenier. Finally, support by stakeholders for the mangrove rehabilitation designs can only be gained if they are engaged. This was tackled by composing a stakeholder engagement plan. In this plan, the following three strategies were formulated: 1) Setting up a bamboo farm, 2) Setting up a Mangrove Vacation Resort and 3) Growing salt-tolerant plants. These strategies can contribute to the economic development of the region if implemented, which could then also benefit the various stakeholders.