Influence of water depth on wave overtopping

The wave overtopping discharge during extreme storm conditions largely determines the required crest height in dike reinforcement projects. In case of future sea level rise, crest heights should be increased significantly, which potentially leads to significant costs and environmental and societal consequences. The available empirical design formulas for wave overtopping are based on data sets that show a relatively large scatter, potentially leading to inefficient design of crest level heights. In this paper a novel approach is presented in which the water depth in front of the dike is incorporated in the wave overtopping formulation leading to a lower scatter and in the case of shallow foreshores also a lower required crest height. The present approach is based on the use of an existing overtopping database (CLASH-EurOtop) and additional generated data by conducting physical experiments(Scheldt Flume of Deltares) and numerical experiments (OpenFOAM) in which the water depth was varied systematically for a variety of test conditions. Based on these three approaches, it is concluded that the wave overtopping discharge (q) is dependent on the water depth. Since this dependency is not included in the present wave overtopping formulation, this paper suggests a method to incorporate this dependency in the present existing formulas by implementing an influence factor for water depth (γd).