**6. Conclusions**

Specific geomorphological features associated with shoreline instability under a high-waveangle condition on the lakeshore, such as the development of sand spits, in several elongated water bodies were investigated, and the segmentation of a water body was numerically predicted using the BG model. It was concluded that a rectangular water body segmented into circular (elliptic) lakes when the probability of occurrence of the wind direction was given by a circular (elliptic) distribution. In each case, the wave-sheltering effect of the cuspate forelands played a primary role. Also, the mergence and segmentation of triangular and crescent-shaped slender water bodies were predicted using the BG model. It was further used for predicting the lakeshore changes when a rocky or sandy island exists in a circular lake. The deformation of a sandy island and mergence of the sandy island to the lakeshore were predicted well.
