Beach Profile Equilibrium and Patterns of Wave Decay and Energy Dissipation across the Surf Zone Elucidated in a Large-Scale Laboratory Experiment

Abstract

Abstract The widely accepted assumption that the equilibrium beach profile in the surf zone corresponds with uniform wave-energy dissipation per unit volume is directly examined in six cases from the large-scale SUPERTANK laboratory experiment. Under irregular waves, the pattern of wave-energy dissipation across a large portion of the surf zone became relatively uniform as the beach profile evolved toward equilibrium. Rates of wave-energy dissipation across a near-equilibrium profile calculated from wave decay in the surf zone support the prediction derived by Dean (1977). Substantially different equilibrium beach-profile shapes and wave-energy dissipation rates and patterns were generated for regular waves as compared to irregular waves of similar statistical significant wave height and spectral peak period. Large deviation of wave-energy dissipation from the equilibrium rate occurred at areas on the beach profile with active net cross-shore sediment transport and substantial sedimentation and erosion. T...