Model for Predicting Beach Changes on Coast with Sand of Mixed Grain Size Based on Bagnold's Concept

Abstract

Returning to the starting point of Bagnold's basic study, sand transport equations were derived. A model for predicting beach changes by applying the concept of the equilibrium slope introduced by Inman and Bagnold and the energetics approach of Bagnold was developed. As a result, the physical rationality of the predictive model was enhanced compared with the original model. Typical beach changes caused by the obstruction of longshore sand transport and associated changes in grain size could be predicted. This becomes a practical tool for predicting three-dimensional beach changes on coasts composed of sand of mixed grain size.