Evaluation Of Runoff Control Effect And Rainwater Utilization Benefit Of LID Measures In Sponge Reconstruction Community

In recent years,the problem of urban rainstorms,floods,and waterlogging has become increasingly serious in China.Urban waterlogging affects people’s normal lives and can even cause casualties and property losses.The severe urban heat island effect makes the city center an easy target for heavy rainstorms,causing frequent "urban seas" phenomena.Urban flood management has become an important issue for urban development.To solve these problems,the concept of "Sponge City" was proposed at a scientific and technological forum on urban development in April 2012 in China.In this study,the Rose Garden community in Yuanzhou District of Guyuan City in Ningxia was selected as the research object.A Storm Water Management Model(SWMM)was developed to simulate the hydrological processes before and after the sponge transformation under different recurrence interval design rainfall in the study area.The control effect of Low Impact Development(LID)measures on rainfall runoff and the influence of different rainfall characteristics on LID measures were studied through simulations.The amount of rainwater storage was calculated under different recurrence interval design rainfalls,and the benefit of rainwater resources in the community was identified and calculated.The main results are as follows:(1)The construction of the stormwater management model(SWMM)for the study area.The generalized model contains 37 nodes.34 pipelines.and three outfalls.Using the Chicago rainfall pattern.four design rainfalls with return periods of 1,5,10,and 50 years were obtained,with total rainfall amounts of 15.14 mm.27.16 mm,32.34 mm,and 44.37 mm,respectively.Based on typical rainfall runoff processes,the calibration and verification of the SWMM model parameters in the Rose Garden community were completed.The results showed a good fit between the simulated results and the measured data,indicating that the model can reflect the hydrological process of the study area to some extent.(2)The control effect of low impact development(LID)measures on stormwater runoff and the influence of rainfall characteristics on the control effect were analyzed.The LID measures effectively reduced the runoff volume and peak flow at discharge outlets 1.2.and 3,with reductions of up to 25%and 10%for the peak flow and total runoff volume,respectively,at a return period of 1 to 10 years,and up to 10%for the water level peak reduction rate.LID measures can appropriately delay the occurrence of the flood peak under different design rainfall levels but have limited effect on the reduction of runoff for larger rainfalls.The control effect of LID measures on runoff peak flow and water level peak reduction rate increases with the increase of the rainfall peak coefficient and decreases with the increase of the rainfall duration.(3)The effectiveness evaluation of rainwater utilization in the residential area under different design rainfall events was calculated.Under the design rainfall events with a return period of 1,5,10,and 50 years,the rainwater accumulation for LID measures in the community was 1 16 m3,225.62 m3,283.38 m3,and 417.47 m3,respectively.resulting in economic benefits of 875.8 yuan,1703.4 yuan,2139.5 yuan,and 3151.8 yuan,ecological benefits of 795.7 yuan,1547.8 yuan,1944.0 yuan,and 2863.8 yuan,and social benefits of 0 yuan,41510.1 yuan,41856.1 yuan,and 35589.1 yuan,respectively.As one of the sponge city pilot cities,the sponge urban construction in Guyuan has a demonstration effect on the sponge city construction in Northwestern arid and semi-arid areas.The study of the LID measure runoff control effect and rainwater utilization benefit in Rose Garden Community based on S WMM model can evaluate the effect of LID measures in sponge renovation communities under different scenarios,provide important technical support for urban sponge construction,promote the implementation of sustainable development strategies,and improve the utilization rate of urban water resources in Northwestern arid areas.This can bring enormous economic,ecological,and social benefits to the city and enhance the overall ecological environment of the city.