STUDY ON MITIGATION OF UNDERGROUND INUNDATION BY EXTREME HEAVY RAINFALL IN URBAN AREA

Abstract

 In recent years, it has been pointed out that the number of local torrential downpours and the amount of rainfall in Japan have increased, and that they will continue to increase in the future. In urban areas, underground spaces such as underground shopping malls have been used. For this reason, when pluvial flood occurs in urban areas with underground space, there is an inundation risk not only above the ground but also underground. In this study, pluvial flood analysis was done using assumed the maximum rainfall, and the inundation risk of an underground mall was evaluated. Then, using the data of flow velocity and water depth obtained from the analysis results, the safety evacuation of the underground mall was examined by calculating the specific force per unit width. In addition, as a countermeasure of underground inundation, the effect of disaster prevention by installing flood boards was examined. From the research results, it has been shown that installation of waterproof boards was effective in reducing the damage caused by underground inundation.