A Study Of The Application Of Swmm On Urban Storm Water Simulation

Urban flooding is an inevitable problem for many cities around the world. With the rapid accelerating urbanization process, urban flood control and disaster mitigation issues, have become more and more noteworthy not only by the government but also by public. On the setting that both of the global climatic change and the high-speed urbanization have affected the urban hydrology, aiming at current situation of high-frequency urban waterlogging, based on the theory of urban stormwater model and the simulation technology, a region of local city was choose as study area and some research of analysis about the process of the stormwater with usage of PCSWMM has been present. The results of the thesis listed as following:(1) Based on the practice of the study area construction model, this paper put forward the building methods of urban stormwater model including the basic data processing, the subcatchment dividing, the setting of model parameter, the sensitivity analysis, the model micro-level calibration and the analysis of simulating scenario design, which can provide reference for other urban area stormwater process simulation analysis, rainfall and flood risk assessmenting and disaster prevention and mitigation forecasting.(2) According to the equation of the storm intensity in the study area, the Chicago Hydrograph Model (CHM) has been used to synthesize four different rainfall scenarios in diverse recurrence intervals. The result Indicates that when the recurrence interval T=1a,2a, the rainfall precipitation amounts to the standard of heavy rains; when the recurrence interval T=5a,1Oa, the rainfall precipitation amounts to the standard of torrential rains.(3) The feasibility of model parameter calibration and the micro-level calibration method with the objective function of the comprehensive runoff coefficient in the absence of measured data has been verified. The verification towards the robustness of the model calibration parameters indicates that with the adjustment of the iterative calibration for many times, the calibration parameter has a good adaptability in common recurrence interval and can be designed to simulate the process of the stormwater. (4) By using PCSWMM software to analyze rainfall scenarios in study area, a simulation analysis about the workings of the drainage network has been present. The result shows that the study area is likely to suffer from ponding and waterlogging, when it meet with heavy precipitation (rainfall exceeds50mm in24h) using the present drainage standard (0.5-3a); When the reoccurrence interval T=1a or2a, the study area won’t suffer from large-area waterlogging. But when the reoccurrence interval T=5a or10a, many junctions will suffer from ponding or flooding, also many pipes will be surcharged. And it will present a certain danger to public security.(5) Based on the recognition capability of bottleneck of the drain-pipe network in designed rainfall scenarios, the measures to improve the drainage network in study area have been proposed:enlarge the diameter of the drain-pipe; consider adding the laying of water permeable brick and increasing the percentage of greenbelt, thought which the percentage of the impervious area and then lower the risk of flood in this area can be reduced.