Hydrological Effects Simulation Evaluation Of Low Impact Development Model Based On SWMM

This research is based on the SWMM model(Storm Water Management Model),LID measures(Low Impact Development)as the technical means,according to the concept and specifications of the sponge city construction,and the Pingfeng campus of Zhejiang University of Technology as the research area to build low-impact development Rainwater drainage simulation system,and simulation of runoff flow and rainwater network overload in the study area before and after LID measures,and a systematic assessment of the sponge city in the study area before and after reconstruction through simulation.In terms of simulation construction: the sub-catchment area is divided and the rainwater pipe network is generalized based on the land use status of the area,vertical elevation,rainwater pipe network and other data,and the research area is generalized to 954 sub-catchment areas,356 nodes,341 Pipe section,and 6 discharge ports.The Chicago rain pattern was used to form the corresponding rainfall intensity data under the six recurring periods of P = 2,P = 3,P = 5,P = 10,P = 20,and P = 50,which were used in the subsequent research simulation.In terms of LID measures,after comparison and selection of the scheme,29833m2 of rain garden,269687m2 of sunken green space,228378m2 of permeable pavement and 150146m2 of green house were selected according to the actual situation of the campus,and the cost calculation was carried out.Finally,according to the existing problems in LID design and construction,an appropriate design strategy is proposed.The simulation results show that: in terms of reducing flood peaks,the increase in runoff control rate at different recurrence periods after LID than before LID is: 0.338 at P = 2,0.339 at P = 3,and 0.341 at P = 5.0.348 at P = 10,0.323 at P = 20,and 0.335 at P = 50;the decreasing ratios of the peaks of the outflow are respectively,drain 3: 52.39% at P = 2;34.09% at P = 5;P = 10 is 24.79%.Drain 6: 62.98% when P = 2;52.78% when P = 5;38.75% when P = 10.Play a very good Hong Feng reduction effect.In terms of rainwater pipe network load,under the three recurrence periods of P = 2,P = 5,P = 10,and P = 50,the maximum percentages of node overflow and pipe network overload after LID are about 20%,respectively 50%,60%,35%,which greatly eased the pressure of the rainwater pipe network.In terms of water quality improvement,the total pollutant load reduction rate after LID is reduced by 40%-50% than before LID,and the pollutant at the discharge port is also significantly reduced,indicating that the low impact of LID development has a certain effect on the water quality and water quality of the study area.This research system studies the plan,simulation and evaluation of the regional LID transformation.The research results are of great significance for constructing the regional rainwater system,increasing the rainwater utilization rate,and implementing the concept of sponge city construction.