Experimental Study of Wave Overtopping on Seawalls

Abstract

Wave overtopping is a key process in coastal environment. The assessment of the wave overtopping rates is an important aspect in the design of different coastal structures, such as seawalls. It was found that increasing the roughness of the seawall slope has significant impact on reducing the wave overtopping rates due to its energy dissipation effect. This study presents the study of modeling wave overtopping using experimentally to investigate the effect of energy dissipators on reducing wave overtopping discharge for sloped seawall 2H:1V with an inherent or artificially added degree of roughness. Experimental tests were conducted in the wave flume at the Hydraulic laboratory of Irrigation and Hydraulics Department, Faculty of Engineering, Ain Shams University. Different models were tested under various wave and water depth conditions to examine the efficiency of the two types of energy dissipation measures (submerged breakwater &two-layers of riprap); increasing the roughness of the seawall slope and construct a submerged breakwater in front of the wall. Only non-breaking waves are investigated. The tested models include a smooth seawall, a smooth seawall with submerged breakwater in front of it at variable distance and a rough seawall with two-layers of riprap and varying the stones height. The impact of the proposed energy dissipation measures was quantified by comparing the obtained results to known wave overtopping estimation formulae in literature where no such measures were adopted and accordingly the reduction factors for these measures were deduced. Keywords: seawalls, wave overtopping, wave energy dissipation, experimental modelling.