PREDICTION OF URBAN INUNDATION CAUSED BY THE LEVEE BREACH OF THE ARAKAWA RIVER AND ITS APPLICATION TO THE INUNDATION RISK OF FACILITIES

Abstract

 In recent years, river floods due to torrential rains have frequently occurred under the influence of climate change, while typhoon floods have been increasing. It’s still fresh in memory that Typhoon No. 19 in 2019 broke 140 dikes in 71 rivers nationwide and caused serious damage. In this study, numerical prediction calculations were performed for the 23 wards of Tokyo, assuming the levee on the right bank of the Arakawa river breaks. This elucidated the generation and expansion process of inundation due to Arakawa flooding. Furthermore, based on these results, the following two points were examined, which are considered to be seriously damaged when the levee of the Arakawa river were breached. (1) Focusing on K subway station, we analyzed the inundation process inside the station and in the tunnel, elucidated the inundation process, and verified the damage mitigation effect of the subway. (2) Focusing on Adachi Ward and Arakawa Ward, elucidating the flooding process up to the main facilities requiring special attention, and examined evacuation measures for hospitals and welfare facilities for the elderly.