Abstract: Global climate changes and increasingly frequent extreme weather events lead to higher frequency and intensity of urban flooding disasters. In-depth study on flood inundation over typical urban streets becomes essential to understand flooding mechanism and work out effective disaster-mitigating strategy and measures. This study establishes a flood inundation physical model for laboratory experiment to represent a urban street system and its complicated structure, inluding roads, sidewalks, buildings, greenbelts, and other street facilities. From the experimental results, we obtain a quantitative analysis on the effect of building density and greenbelt arrangement on flow inundation process. We come to the conclusions that (i) on the model road, the celerity of dam-break waves depends on initial water depth in the reservoir and road characteristics, while the influences of buildings and greenbelts are insignificant. (ii) Adding greenbelts or buildings to the system reduces the flow cross-sectional area, thereby increasing the flow depth on the road during flood events, but it can reduce the water volume around buildings or increase flow resistance so that more water is concentrated on the road. (iii) Peak depths in front of buildings are roughly proportional to the initial reservoir depth, and a large initial reservoir depth will cause a much stronger impact force on the buildings. This study supplies data for numerical model calibration and helps design urban streets facing outburst flooding threat.

Key words: urban flood, flood routing, urban streets, physical model, experimental investigation