INUNDATION PROCESS IN THREE CITIES OF MUSASHINO, MITAKA AND CHOFU FOR THE LARGEST POSSIBLE TORRENTIAL RAINFALL

Abstract

 Heavy rainfall has been occurring frequently in many areas due to climate change in recent years, and Typhoon No. 19 in 2019 caused a lot of damage due to levee failures, river overflows, and internal flooding in many parts of Japan. In this study, inundation forecasting calculations for Chofu City and Mitaka City, which were actually damaged by Typhoon No. 19, as well as the adjacent Musashino City, were conducted using S-uiPS, a sophisticated inundation forecasting method, for the assumed maximum rainfall. This method has been used in the past for the 23 wards of Tokyo and the cities of Kawasaki and Yokohama, and was applied to Chofu, Mitaka, and Musashino in this study. In particular, we focused on depressions and underpasses, where the inundation depths are particularly pronounced, to elucidate the inundation process. The maximum inundation depths of the three cities and the 23 wards of Tokyo were compared and discussed using various quantities related to the sewerage network.