BEACH CHANGES AT EAST END OF HAMAMATSU-GOTO COAST NEXT TO TENRYU RIVER MOUTH

Abstract

 At the Hamamatsu-Goto coast next to the Tenryu River mouth, a groin has been constructed and beach nourishment was carried out between 2012 and 2020 using 7.3 ×104 m³ of the riverbed material of the Tenryu River to widen the foreshore at a narrow beach in front of the seawall, where once wave overtopping occurred. Monitoring surveys of the beach changes, such as the bathymetric surveys around the groin and UAV measurements, were conducted after the extension of the groin to evaluate the most appropriate depth of the groin. In this report, the intermediate results of the monitoring surveys were reported. It was found that the beach width has increased owing to the beach nourishment as well as the recovery work of the detached breakwaters and the construction of the groin.