VIOLENT AND IMPULSIVE WAVE OVERTOPPING AT VERTICAL WALLS WITH LARGE FREEBOARDS

Abstract

Vertical walls are designed and built to protect coastal areas or harbours. Typically, these structures are installed in relatively deep water where incoming waves are reflected without breaking. In such cases the available prediction methods for wave overtopping discharge are well established. When the relative water depth h/Hm0 becomes smaller, waves start shoaling on the foreshore and breaking can occur leading to impulsive conditions. The present overtopping prediction methods (EurOtop, 2018) under impulsive conditions have been proposed by Van der Meer and Bruce (2014) including data from the VOWS project (Bruce et al.; 2001). Wave overtopping is strongly related to the relative freeboard Rc/Hm0, and for impulsive overtopping EurOtop suggests that for Rc/Hm0 greater than 3 there still might be significant overtopping but there is no data to validate such an extrapolation. Also the well-known overtopping graphs of Goda (2000) show that overtopping could be present for very large freeboards and impulsive waves. The objective of the present research is to investigate the mean discharge and volumes per wave from impulsive and violent overtopping at vertical walls with very large freeboards (up to Rc/Hm0 = 10).