PREDICTING SEAWALL OVERTOPPING BY BIMODAL SEAS

Measurements at HR Wallingford have indicated that bimodal wave conditions may be a worst-case condition in the design of some coastal structures (Hawkes et al. 1997). This paper describes a simple method for predicting the mean rate at which embankments are overtopped in bimodal seas. Use is made of the H&R model (Hedges and Reis 1998). This model is more soundly based on physics than earlier procedures for predicting overtopping discharges. It has also been shown to provide the most promise for future development (Hawkes 1999). Its use in predicting mean overtopping discharges in bimodal seas is the latest development. Comparisons between measured rates and model predictions show generally good agreement over the wide range of conditions covered by the tests reported here.