Wave Overtopping and Wave-Induced Loads on Coastal Sea Walls

Extreme storm events and a potential sea level rise are great threats for low lying areas, e.g. in Belgium. Both the wave-induced loading and wave overtopping of vertical coastal structures are identified as the main challenges with respect to coasts in low-lying countries. Therefore, the overall objectives of this study are to understand and measure wave-induced loads on vertical storm walls caused by overtopping waves and shallow foreshores. Hydraulic model tests were performed (scale 1:25) in the wave flume of the Department of Civil Engineering at Ghent University. The foreshore (1:35) and the dike (1:2) were built with two different dike crest levels (+9 mTAW and +10 mTAW) and two promenade widths (10 m and 30 m). The analysis of the tests showed that the interaction between overtopping rate, freeboard, wave conditions and water level influences the wave-induced loads significantly. Empirical relationships were developed for the present setup combining the dimensionless force with the dimensionless overtopping.