Study On The Intensive Low Impact Impact Renovation Of Urban Area Based On SWMM Model

In order to accurately simulate the hydrological process,many related hydrological simulation models have been established at home and abroad,including the SWMM(storm water management)developed by the U.S.Environmental Protection Agency Model)rainstorm flood management model has good applicability in the simulation of urban hydrological process.In this paper,SWMM model is used in the research area selected in this paper,and the hydrodynamic model before and after adding low impact impact facilities is established and analyzed and calculated,so it is concluded that adding low impact facilities has a very good positive effect,in addition,low impact facilities are also selected and combined The corresponding optimization is carried out for the impact facilitiesThrough the simulation of SWMM model,the conclusions are as follows:(1)SWMM model was established for the small area before low impact impact reconstruction.The simulation results show that with the increase of rainfall return period,multiple rainwater wells in the small area generate overflow condition.When the rainfall return period reaches 10 years,there are 3 rainwater inlets in the small area overflow condition,and the overflow rainwater directly flows to the ground of the small area,affecting the normal travel of residents.When the rain intensity increases to a certain extent or the rainwater inspection well is blocked by the silted up sediment,it will also form the community waterlogging,endangering the life and property safety of the residents.And the method of Nash coefficient is used to calibrate the hydrological parameters of the plot.After several adjustments,the rain flood model with small error with the actual runoff situation of the plot is simulated(2)The SWMM model is established for the small area after the transformation of low impact impact facilities.The simulation results show that in terms of Hydrology:when the rainfall intensity is one to one hundred year return period,the low impact facilities can delay the occurrence time of the peak runoff of rainwater,and greatly reduce the peak runoff.For the peak flow control rate of one year,five years,ten years and one hundred years 75.2%,77.8%,77.5%and 65.5%respectively The reduction rates of the four return periods are 75.8%,74.5%,70.2%and 25.9%respectively.The control ability of low impact impact facilities peaked in the return period of five to ten years,and then gradually weakened with the increase of rainfall intensity.The simulation results show that in terms of water quality:according to the change of parameters such as the permeability of the underlying surface after the reconstruction and the flow direction of rainwater runoff,the pollutant content of each underlying surface decreases or increases in varying degrees.However,from the comparison of pollutant quality before and after the node load at the only discharge outlet of the community,it can be seen that the control rate of low impact impact facilities for pollutants is more than 50%.However,compared with the recommended national standard technical code for rainwater collection and Utilization Engineering(GB/T 50596-2010),the rainwater quality collected by the rainwater collection device designed in the community can be seen that the COD content meets the standard,but the SS content does not meet the standard,and the initial rainwater waste device should be added later.