Rearch On Risk Identification Of Urban Waterlogging Based On SWMM

The permeability area of the underlying surface in cities is rapidly decreasing along with the development of society and the advancement of urbanization, which resulting in destroying the equilibrium between the rainfall, water storage and drainage. Meanwhile, the capacity of urban’s rainwater storage and rainfall drainage in cities are reducing greatly. At the same time, the development of society also affect on the ecological environment of the earth, such as the Greenhouse Effect, the El Nino Phenomenon, the Heat-island Effect, terribly those phenomena become more and more serious, so that extreme disastrous weathers occur frequently. With the rapid development of urbanization and the frequent happening of extreme disastrous weathers, the risk of the urban water-logging disasters increased greatly.Identification solution of waterlogging risk urban is putted forward in this paper by using SWMM model after analyzing the water-logging problems existing in the major cities of China. At the first, reasons of urban water-logging and the harm of urban water-logging are analyzed and summarized in this paper. According to various factors including classification principle, waterlogging affect object of city, the city waterlogging is classified by the water depth, which is scientific and reasonable.Secondly, water depths of the test area are obtained by making rainstorm waterlogging experiment under different conditions, the different conditions mentioned here are two alternative rainfall intensity and four different underlying surface, with or without drainage pipeline. In addition, test results are calculated and analyzed, and the ratios of catchment area and accumulated water area are obtained when test area occurred different waterlogging grade.Furthermore, SWMM model of study region is established by considering SWMM storm water management model, study region engineering example and using various datum such as drainage pipeline layout, topographic map and land-use type. What’s more, the model is analyzed separably in the three different rainfall scenarios namely P=20a, P=50a, P=100a. Besides, which area is more prone to be waterlogging area is found in three different rainfall scenarios, and the corresponding depth of waterlogging is calculated. At last, the waterlogging risk grade zoning map on the study area is received combing with grade divide of urban waterlogging and the survey region’s urban waterlogging risk grade in different rainfall scenes.In conclusion, the grade of urban waterlogging are divided in this paper. Combing SWMM model and study region engineering example, a method for identify the urban waterlogging risk grade is proposed, which provide important references for early warning of flood control and disaster prevention or mitigation.