Variations in Vertical Seawall Geometry and the Effect on Wave Overtopping Discharges

With sea level rise and the potential impacts of climate change, wave overtopping of seawalls around the UK is of increasing concern and importance. This paper briefly describes the current information available to designers and engineers for predicting overtopping discharge of vertical or steeply sloping structures. This information is found to be lacking for complex structural configurations. Three physical model experimental studies undertaken for Arup are described and the measured discharges used to investigate the influence of the different structural elements including a secondary (set-back) wall, an emergent berm or other element in front and toe depth. The majority of the elements reduced mean overtopping discharge compared to a simple vertical wall. A set-back wall, even a small one designed for vehicle containment, was the most effective element at reducing mean overtopping discharge. The three studies also highlight the value of physical modelling in accurately quantifying the overtopping for the different structure configurations, particularly for more complex structures.