Storm Surge Disaster Caused by Typhoon Jebi, T1821, at Fukae Harbor in Japan

摘要

Facts of the storm surge in Fukae Harbor caused by Typhoon Jebi, T1821, on 4 September, 2018 were clarified by the recorded data. The maximum tidal level (TL) occurred between 14:16 and 14:18, and was estimated to be 305 cm. The maximum deviation of the TL from the predicted TL was 254 cm. The main factor in the storm surge was the wind effect of the southerly. The outside maximum water level in Fukae Harbor was 336 cm, and was 36 cm higher than the TL of the time due to wind waves generated by local winds. The flooding was produced not only by the overflow caused by the storm surge but also by waves overtopping. If the storm surge had occurred at the maximum TL of the year, flooding would have produced by the overflow alone. The hazard maps of inundation by flooding from rivers and of inundation inside levees very nearly express the inundation area resulting from the storm surge. Overlaying evaluation of hazard maps of similar disasters is important in a perspective of risk detection. As the present seawalls may not be able to prevent the greatest storm surge, both tsunamis and storm surges should be considered in coastal disaster prevention.