Coastal impacts of super typhoon Hagibis on Greater Tokyo and Shizuoka areas, Japan

A post-event survey of the coastal impacts of Typhoon Hagibis was conducted in the Greater Tokyo and Shizuoka areas. The typhoon's intensive landfall generated the highest-level storm surges recorded in the study area with a maximum sea-level anomaly of nearly 2 m at the head of Tokyo Bay. Highly populated coastal areas in the inner sheltered part of Tokyo Bay were subject to only minor damage partially because the peak storm surge occurred during a low spring tide. High water levels along the coastline facing the Pacific Ocean mostly measured 4-8 m above the mean sea level, the exception being the Seisho coast, where extreme wave runup reached over 10 m above the mean sea level. The high water levels predominantly caused by energetic swells were comparable with the crest heights of defense structures in a broad range of the study area. The intensive typhoon did not trigger catastrophic flood damage, but caused minor flooding due to wave overtopping, and there was substantial damage to coastal infrastructures along the coast. This paper presents both an overview of and detailed information regarding the coastal impacts of the intensive typhoon along the highly altered coastline with complex geometry.