Abstract:
In recent years, Shijiazhuang city suffers a gradual increase in extreme weather, and short-duration local heavy rainfall occurs more frequently, leading to large-scale urban waterlogging and serious losses. In the paper, the small structured grids are used to establish a fine urban storm waterlogging model on the basis of high precision DEM data. The model accurately reflects the housing construction, urban roads, city overpass system, drainage canal system and other typical urban geographic elements. Partitioned runoff coefficients and roughness are used on different types of land. Drainage districts of the urban pipeline system are refined to actual control blocks of each rainwater trunk, which simulates the actual pipe network drainage process. The point source terms are set to simulate pumping stations at the position of underpasses. The model accurately simulates various phenomena with typical urban characteristics, such as the flow blocking by building construction, the rainwater outflowing from courtyards, the catchment and waterlogging in a low-lying area, for instance, the areas under underpass bridges and overpass, waterlogging routing on the urban roads, and flood water drainage by the pipe network and pumping stations. Urban waterlogging area, waterlogging position and flooded roads are calculated and counted. The Shijiazhuang' waterlogging is classified into three levels: high, medium and low. The model has a good application value. Based on simulation results of the specific rainfall events, the research has drawn some conclusions on risk analysis and classification, providing a useful reference for Shijiazhuang's flood prevention, disaster reduction and risk management.