Research On Stormwater Management Of Tsinghua University Based On SWMM

Since the 21 st century,China's urbanization process has gradually accelerated.Urbanization drived sustained economic growth,promoted social progress,but also brought serious flooding.Urbanization makes urban impermeable area increased,eventually leads to an increase in runoff coefficient,an increase of the peak flow and an advance time of flood peak.Through the application of SWMM model in Tsinghua University,this paper analyzed the impact of rainfall on the Tsinghua University waterlogging,and then explored the reasonable solution of urban waterlogging problem under the background of modern stormwater management concept.The SWMM model is a mathematical physics distributed model,which can meet the requirements of urban stormwater management and environmental management.According to the data of terrain,drainage network and so on,we built the SWMM model of Tsinghua University.Using the measured data of rainwater depth,the survey data of main ponding area and so on,we verified the simulation result of the model.According to the simulation results of the model,we analyzed the outflow process of river,road and drainpipe under different rainfall conditions,found out the main ponding area.With the increase in rainfall,the value of the outflow increased but the growth rate decreased.This shows that more rainfall is detained in the campus,eventually leading to the occurrence of waterlogging.In the all ponding area of Tsinghua University,the ponding amount of 10 largest ponding area account for 44.0% of the total,this shows that the problem of waterlogging on campus can be solved very well through the treatment of the main ponding area.This paper analyzed the specific causes of the ponding area according to the underlying condition and the upstream and downstream environment,and then gave reasonable suggestions to make full use of the drainage capacity and the infiltration capacity.Through the model simulation results,we found that the ponding amount was significantly reduced,Indicating that the proposed suggestion's effect is obvious to solve the problem of waterlogging on campus.Since 2012,our country has designated the national strategy as the development of ecological civilization.We put forward the concept of sponge city and compiled the “Technical guide for the construction of sponge city”,reduced the runoff coefficient of urban areas through the joint management of source,transmission and discharge.The runoff process in the watershed is dynamic under the rainfall condition,so the storage capacity of the storage facilities should also be dynamic.We should not only consider the total amount of control,but also consider the process control.However,the construction of sponge city paid much attention to source section in the actual project and the effect is poor.Under small rainfall events the current source section management may have a negative impact on the river ecology;under heavy rainfall events it may have insufficient effect to reduce the peak flow.For the source section management,this paper proposed a transformation method to consider the process control,compared the effects of these two methods by modeling.The simulation shows that the new method not only eliminates the negative impact on the river ecology,but also improves the ability to reduce the peak flow.