Research On The Construction And Application Of Storm Water Model In Mountainous City Under The Sponge City

With the further development of urbanization,the problem of rain and flood is becoming more serious.Urban stormwater runoff and peak flow has increased in recent years because of the increase of the frequency of extreme rainstorm events.And this results in heavier load of urban drainage network and high frequency of urban waterlogging.Because the urban stormwater management model provides reasonable basis of low impact development measures in domestic sponge city construction,the establishment of urban stormwater management model,which can achieve simulation analysis of rainfall runoff and drainage of pipe network system,is of great importance.First the article summarized current situation and application of urban stormwater management model at home and abroad,and then the Jiangbei District in Chongqing was taken as research object.Subsequently SWMM model was employed to carry out simulation analysis of the research object under rainstorms with different recurrence period.On the basis of SWMM model,LID regulation was adopted for the research object with the combination of sponge city construction goal.Then we simulated rainfall runoff in research area after LID regulation and made a comparison with rainfall runoff under the traditional development to intuitively reflect regulating effect of LID measures.The research provides theoretical support and technical guidance for LID measures in sponge city construction.The main results of this paper are as follows:(1)Structure,principle and modeling steps of SWMM model is summarized.Uwater-Drainage is employed to build SWMM model of research area with combination of land use,topography and current situation of pipe network.Subsequently operating parameters are determined and reliability of model is tested and verified.(2)Rainfall runoff and drainage of network in research area is simulated under rainstorm with different recurrence period.The result showed that there is strong correlation between rainfall and runoff.The greater the rainfall intensity is,the greater the runoff is and time difference existed between rainfall peak and runoff peak.According to the simulation result of drainage network,network in research area can only deal with heaviest rainfall in years so the risk of serious waterlogging increased with the increase of recurrence period.(3)Design values of LID measures control index in research area are determined under the goal of sponge city construction.Design value of green roof,permeable pavement of roads,permeable pavement of squares,grassed swales and concave greenbelt are 17%,49%,41%,2% and 3%..Total runoff and peak runoff in research area are reduced significantly after LID regulations which increased design frequency of drainage network and decrease the risk of urban waterlogging.