Based On Gis And Swmm Urban Flood Simulation And Analysis

With global Climate become warm, rainfall will occur more frequently, accompanied by the accelerating process of urbanization, flood control in urban planning and construction is very important. Cities are the main places where human lives, human activities have changed the city and its surrounding hydrographic environment, such as topography, underlying surface characteristics, stream, river channel, ground water permeability, hydraulic facilities, etc. Original natural drainage system is replaced by the city sewer. Concrete pavement, building, residential district, infrastructure establishment and so on, all these elements make impervious surface area increasing and pervious surface area decreasing. Although the undeveloped places around the city retain its original natural state, the residential and the place of construction formed the complex rainfall-runoff system, the urban rainfall-runoff simulation becomes more complex. Therefore, hydro-geological assessment of environmental impact on urban flooding process, study the mechanism of urban flooding, flood routing process simulation to predict the flood disaster loss are the focus of nowadays research.This paper introduced the domestic and foreign rainfall-runoff simulation models based on the theory of urban hydrology, and starting from urban terrain, the formation of watershed boundary precipitation, the urban surface runoff and the convergence process content in the watershed boundaries have been analyzed, also the rainfall, interception and infiltration, evapotranspiration, groundwater that affect the formation of urban rainfall runoff then the causes of urban flooding have been analyzed. In view of the complexity of the urban hydrological environment, urban hydrological environment has been generalized to model urban hydrological. In this study, the U.S. Environmental Protection Agency EPA's SWMM model has been adopted. With the aid of GIS geoprocessing capabilities and hydrological analysis capabilities, the urban hydrological environment has been generalized.The water flow direction and the boundary of drainage area have been extracted from DEM of the city. With the SWMM model, rainfall changes over time resulting from convergence of computing surface runoff and pipe flow have been simulated. The distribution of pooling points, node flow, pipe flow state results and the node flow tables have been shown. Finally, according to analysis results, the influence factors on city flooding have been discussed.