BEACH CHANGES BY STORM WAVES

Abstract

Monitoring of beach profiles was carried out during one-year period at two sites located 3 km apart along a Pacific beach, Japan. These two sites are composed of beach sand with different grain size: 0.76 mm and 0.26 mm. It was found that the shoreline did not move even in storm wave events at the site with 0.7 6-mm sand, where the "seesaw mode" profile change took place in the subaerial portion of the beach. It was also found that the shoreline was not always retreated by storm waves at the 0.26-mm sand site, where the "parallel mode" profile change dominated, at the time of presence of bars working as a submerged breakwater to protect the beach from erosion.