Numerical Model of Beach Profile Evolution in the Nearshore

A numerical model was developed to simulate hydrodynamics (waves, currents, and mean water level), cross-shore sediment transport, and beach profile evolution in the nearshore assuming negligible longshore transport gradients. Particular focus was put on describing the response of the subaerial region of the profile, including the foreshore and the berm, as well as the exchange of material between the swash and the surf zone. The model consists of different modules describing wave transformation, cross-shore currents, mean water elevation, and cross-shore sediment transport. For the purpose of model calibration and validation, detailed, high-quality data on hydrodynamics and beach profile response from the SUPERTANK data collection project were employed. The experimental cases studied encompassed several types of profile evolution, including berm erosion and bar formation, berm flooding and erosion, and offshore mound evolution for a narrow- and broad-crested mound. Overall, good agreement was obtained between calculations and measurements, especially for the foreshore and the berm, whereas the calculated bar shape was smoother than the measured shape. The model produced robust and reliable predictions of cross-shore transport and profile evolution for the cases investigated. Subsequent work in model development will involve dune erosion and overwash as well as validation toward field data.