Salt Marshes are a coastal ecosystem which have numerous benefits as coastal defense such as wave attenuation and can adapt to sea level rise. Wave flume tests, using a scale model of a cross-section of a salt marsh adjacent to a dike, were conducted in the Hydraulic Laboratory, to quantify the effectiveness of such a salt marsh system as flood defense (part of the Living Dikes research program).

This thesis focuses on the reduction in wave run-up due to salt marshes on the adjacent dike, with a focus on high water levels. The wave run-up was measured using video processing, using a newly created algorithm to track the water movement on the dike slope. The results show a significant reduction in wave run-up due to wave attenuation over the salt marsh, further dependent on the presence of vegetation and the water depth on top of the salt marsh. The measured wave run-up values show some differences with values acquired using the TAW/EurOtop wave run-up formula. There is a correlation found with the wave steepness, where waves with a lower wave steepness do match the equation, and show a larger deviation for increasingly higher wave steepnesses.