Model of Beach Profile Change under Random Waves

Abstract

A numerical model is developed to calculate the average net cross-shore transport rate and beach profile evolution under random waves. Cross-shore transport formulas for random waves are derived by superimposing the transport from individual waves, which belong to an ensemble that represents the random wave field. The transport relationships for individual waves are based on experiments with monochromatic waves in large wave tanks. The model is validated using beach profile data from the SUPERTANK Laboratory Data Collection Project. Three different types of profile evolution events are studied, namely equilibrium erosion with bar formation, berm flooding, and the impact of breaking waves on an offshore mound. The berm flooding tests include the erosion of a well-developed summer berm and the erosion of an artificially constructed foredune, and the offshore mound tests encompass narrowand broad-crested mounds. The new model respresents an attempt to consistently treat random waves in all components of a beach profile change numerical model. Previous approaches to model the profile evolution under random waves have typically involved using statistical wave measures in equations primarily developed for monochromatic waves.