NUMERICAL ANALYSIS OF TYPHOON-INDUCED WAVE SETUP SURGES ALONG WEST COAST OF SAGAMI BAY

Abstract

 Sagami Bay is an open and deep sea facing the Pacific Ocean. The storm surge here has a very small wind set up, and the water level mainly rises due to the suction effect. In particular, because of its steep topography on the western coast, wave maintain its height even in the shallow coastal area and break in the narrow surf zone causing the beating Wave Setup. The analysis of the storm surge including the high waves and Wave Setup (Wave Setup storm surge) in the Sagami Bay was conducted for Typhoon No. 12 that struck in July 2018(T.1812).As a result, on the western coast of Sagami Bay, high waves directly invade the coastal area due to local surf zone breaking, causing fluctuating Wave Setup with the maximum height of 2.7 m above the mean sea level. It was shown that the area where the high surge and waves are generated is tightly related to the coastal current system, and the generation area is geographically fixed. At these places, the risk of wave overtopping disaster is extremely high.