The Conundrum of Specifying very low Wave Overtopping Discharges

Abstract

The design of certain seawalls / breakwaters has often been required to achieve very low targetovertopping discharges when these structures protect vulnerable infrastructure or activities. Thebalance between economically viable protection and performance requirements is often difficult toachieve without good knowledge on low overtopping. The paucity of data in this space and the highuncertainties associated with existing methods, increase the challenge. The occurrence of a lownumber of overtopping waves has the consequence that any test results are substantially moreaffected by the inherent variation of random waves, therefore more uncertain. The physical model testresults presented hereafter were successful in obtaining low to very low overtopping discharge data.For low / very low overtopping, these test data present considerable scatter relative to the latestempirical prediction. A number of repetitions was performed for conditions giving very low overtoppingdischarges, which illustrated the inherent uncertainty associated with low overtopping