Numerical Simulations of Wave Setup over Barred Beach Profiles: Implications for Predictability

Abstract

Numerical simulations of cross-shore wave transformation and associated wave setup were performed for 100,000 realistic combinations of wave height, period, and beach profile. Results of numerical simulations were compared with a widely used empirical predictor of wave setup, and the outcome was a large variability in setup relative to that calculated by the empirical predictor. The variability, comparable in magnitude to the scatter around the empirical predictor developed with field observations, arose from wave energy dissipation over the cross-shore profile that was not taken into account. The beach-face slope commonly used in empirical predictors can be a poor descriptor of wave transformation across the beach profile, where most of the wave energy dissipation and setup generation occurs. Shoreline setup appears to be far more dependent on accurate characterization of the offshore profile (e.g., bar location and depth) than the beach-face slope.