On the Shizuoka coast, many detached breakwaters have been constructed since 1970 as a measure against beach erosion. After their construction, sand movement as a sand body which is mainly composed of gravel and has a movement velocity of 260 m/yr was observed in the zone shoreward of these detached breakwaters. Due to the analysis of bathymetric survey data, fine sand movement was also found in the zone offshore of the detached breakwaters apart from the gravel movement near the shoreline. In this study, a model for predicting both the movement of a sand body and fine sand movement in the zone off the detached breakwaters is proposed.
