Numerical Formulation and Model Tests

Abstract

This report is the second in a series on the numerical model SBEACH (Storm-induced BEAch CHange). SBEACH calculates dune and beach erosion produced by storm waves and water levels; bar formation and movement produced by breaking waves are also simulated. The model is empirically based and was originally developed from a large data set of net cross-shore sand transport rates and beach profile change observed in large tanks. The empirical formulation, model sensitivity tests, and a field validation case are described in Report 1. In the present report, Report 2, the capability of the model to simulate berm and dune erosion Is evaluated using recently acquired field data from both US east and west coasts. Hypothetical storm events are also simulated to demonstrate model applicability and potential uses for predicting initial adjustment of beach fill and its response to storm action, including post storm recovery. In addition to describing the field tests, Report 2 provides a complete description of the mathematical formulation of the model and numerical algorithms comprising the solution scheme. Improvements of the model are also presented. The associated wave model has been generalized by using complete linear wave theory everywhere on the profile without shallow-water approximations, a capability important in general applications for irregular bottom profiles subjected to waves of widely ranging characteristics. Refraction has been included, and an option is provided to randomize the wave input for better representing forcing conditions in the field.