Abstract
In a slender water body with a small aspect ratio, the angle between the direction normal to the shoreline and the wave direction exceeds 45 degrees, resulting in the emergence of cuspate forelands and the subdivision of a lake, because of long wind fetch along the principal axis. In this study, the BG model (a model for predicting three-dimensional beach changes) was applied to this problem. Three-dimensional subdivision process of a long slender water body was predicted.