VARIATION OF SAKAWA RIVER DELTAAND REDUCTION IN BEACH WIDTH AROUND SANNO RIVER MOUTH

Abstract

 In the eastern part of the Odawara coast (Miyuki-no-hama coast) located west of the Sakawa River mouth, both shoreline changes in response to the variation of the Sakawa River delta and the shoreline recession due to decrease in northeastward longshore sand transport occurs. In the vicinity of the Sanno River mouth, beach width is narrow, and a submarine canyon develops offshore the shoreline with a steep slope. Because of this, severe wave overtopping occurred during Typhoon No. 19 hit this area on October 12, 2019. In this study, beach changes were investigated using aerial photographs and satellite images including the overall river delta as well as sampling test of seabed material. Based on these field data, a measure to recover the shoreline was considered by beach nourishment using coarse material.