Simulation Study On Rainwater Control Of Sponge City Community Based On SWMM Model

In recent years,with the acceleration of urbanization process,the increase of urban hardening area cause the frequence of urban waterlogging.Urban improve the utilization rate of precipitation to alleviate urban waterlogging.Based on the analysis of existing data and field investigation data in the research area of a university teachers' apartment district,this paper uses SWMM model to simulate and research the rules of rainwater in different recurrence periods and different low-impact development modes to control the rainwater runoff in the study area,reduce the pressure of rainwater pipe network and alleviate urban waterlogging.Four modes of low-impact development facilities allocation were designed in this paper,Which are mode 1 has green roof(accounting for 15.95%),sunken green space(accounting for 13.81%)and permeable pavement(accounting for 21.81%);mode 2 has rainwater garden(accounting for 9.26%),sunken green space(accounting for 13.81%)and permeable pavement(accounting for 21.81%);mode 3 has green roof(accounting for 15.95%),rainwater garden(accounting for 9.26%),and permeable pavement(accounting for 21.81%);mode 4 has green roof(accounting for 15.95%),rainwater garden(accounting for 9.26%),and sunken green space(accounting for 13.81%)respectively.The SWMM mode is used to simulate the four modes,and the results are as follows:Firstly,the impervious area accounting for 37.76% of the study area and the green space area accounting for 13.81% of the study area were transformed in mode 1.The volume of the rainwater and the flood in the a-year return period,three-year return period,five-year return period and ten-year return period were reduced by 94%,83.2%,68.6% and 50.4% respectively.The impervious area accounting for 37.76% of the study area and the green space area accounting for 11.41% of the study area were transformed in mode 3.The volume of the rainwater and the flood in the a-year return period,three-year return period,five-year return period and ten-year return period were reduced by 93.8%,82.8%,65.2% and 44.8% respectively.The results show that,the amount of rainfall and flood reduction increases gradually with the increase of the green space area in the condition of the same impervious area.Secondly,the impervious area accounting for 21.81% of the study area and the green space area accounting for 25.22% of the study area were transformed in mode 2.The volume of the rainwater and the flood in the 1a,3a,5a and 10 a of the return period were reduced by 65%,52.3%,43.1% and 24.5% respectively.The impervious area accounting for 15.95% of the study area and the green space area accounting for 25.22% of the study area were transformed in mode 4.The volume of the rainwater and the flood in the 1a,3a,5a and 10 a of the return period were reduced by 54.7%,30.3%,19.4% and 4.5% respectively.When the increase of the green-space area is the same,the volume of rainwater and flood reduction will increases with the impervious area accounting for the same proportion.Thirdly,the rate of peak reduction is 13.6% and the peak delay time in 10 minutes when the recurrence period set as 10 years in the mode 2.The other three modes do not reduce the peak.And the mode 2 also costs lowest,alleviates the node overload and the canal overload by more then 94.8% and 93.3%.It can be seen that Mode 2 is most suitable for deployment in the study area.Finally,it is very important to research the construction of LID in sponge district for the regulation of rainwater and flood,and strive for the early realization of sponge city.