Study for Underpass Inundation Process Caused by Heavy Storm Using High-resolution Urban Flood Model

Pluvial inundations in urban area are caused by localized, heavy rainstorm events, which lead to the severe disaster risks in inundation-sensitive zones. The paper focuses on different rainfalls in analyzing urban underpass inundation process based on high-resolution urban flood model combined with linear blocking boundary method. Included in this study are the construction of high-resolution urban flood model and the method of rainstorm scenarios simulation in a series of different return periods (50, 100, 200, 500, 1000 years) and peak coefficients (0.35, 0.5, 0.75). The profiles on water depth and rapidity of water level rising in underpass are obtained to analyze the inundation process referring to cumulative precipitation and rainfall time, besides, the variations of warning time and rainfall for vehicle and human are analyzed consequently. The results indicate that the variations of inundation are determined by the common effects of rainfall intensity and the time for most runoff travel to underpass. Specifically, the variation of inundation in Jinhua underpass is generally dependent on the rainfall intensity 10 min ago. Besides, it takes much less time for the water rising from 0.4 m to 1.2 m than the time from 0 to 0.4 m, which means when the vehicle is in danger, it needs evacuating without hesitation. The research, therefore, highlights the importance of high-resolution urban flood model in inundation process simulation and the necessity of predicting the inundation process of underpass based on real-time gauge to guide traffic controlling and emergency evacuation.