Abstract: Coastal overwash is a natural process, usually occurring during severe storms and hurricanes, and may cause rapid profile changes in the nearshore. Up to present, only a limited number of three-dimensional numerical models have been developed previously for the effects of overwash, especially runup overwash. This study develops an overwash algorithm and applies it in a three-dimensional coupled wave-current-sediment transport model that integrates the FVCOM model and SWAN wave model, so that we can achieve a morphological model for prediction of the overwash profile evolution. This model is validated using two sets of laboratory data. The results show it is capable of simulating beach profile changes caused by the overwash under different hydrodynamic and morphological conditions. In addition, sensitivity analysis of the empirical coefficients in the overwash algorithm is carried out, and the influences of the coefficients on the model results are discussed.

Key words: wave-current coupling, three-dimensional model, overwash, runup, morphological evolution