A new model for predicting beach changes was developed using the cellular automaton method, taking sand transport under the ongoing and outgoing waves into account independently. The model was applied to predict sand deposition on the backshore with a steep foreshore slope on the Oiso coast. Furthermore, three-dimensional topographic changes were predicted using the model, when a groin with an opening between the landward end of the groin and the land was constructed on a beach. The predicted beach changes well explained the observation results on the Osawa coast facing the Uraga Strait.
