Prediction of Topographic Changes of an Island Composed of Sand Subject to Waves Incident from Every Direction

Miyahara et al. developed a model for predicting the deformation of a circular sandy island using the BG model (a model for predicting 3D beach changes based on Bagnold’s concept), taking into account the development of longshore sand transport due to longshore variation in breaker height. In their model, the calculation of topographic changes was repeatedly carried out, given the wave field predicted using the energy balance equation. In this study, a method to predict topographic changes on a circular island was developed using the BG model without repeated calculations. Assuming that waves are incident to the direction normal to the shoreline of an island with changing wave diffraction coefficient Kd, longshore sand transport was taken into account based on Ozasa and Brampton’s concept. Calculation results were in good agreement with the results of the previous study.