LID Evaluation Method Research Of Urban Stormwater Based On Sustain And SWC

Inorder to alleviate the serious urban waterlogging problems caused by rapid urbanization, best management practices, low impact development and green infrastructure, and etc. have been developed.This paper applied the National Stormwater Calculator, which is developed by USEPA,to assess the runoff reduction potential of BMPs, LID and GI in Jiaxing Jiangshuigang region of Zhejiang Province under the historical scenario(2003), current scenario(2014) and planning scenarios(all possible LIDare fully implemented), based on local soil types, topography, rainfall, evaporation, and land cover data.It is showed that the impervious cover has increased 12.25%from 2003 to 2014, as a result, the annual runoff increased by 125.99 mm and annual runoff rate increased by 11%. Therefore, impervious cover is the main factor for producing runoff.Compared with the current scenario, the runoff rate decreases by 20% and the infiltration rate increases by 22% under the planning scenario. It is demonstrated that LID is effective to reduce runoff of rainfall under 30 mm in the simulation region, however, it has limited effect to control rainfall with return period of over 5 years. For extreme heavy rainstorm events, it is necessary to further improve the design capacity of LID or take emergency practices such as discarding, bypass or temporal storage.This paper applied SUSTAIN(System for Urban Stormwater Treatment and Analysis Integration Model) to assess the runoff and pollution load reduction of Qingwanjiayuan residential areaof Zhejiang Province under predevelopmentscenario, current without LID/BMP facilitiesscenario,current with LID/BMP facilitiesscenario. Simulation results show that compared tocurrent without LID/BMP facilitiesscenario, current with LID/BMP facilitiesscenario can reduce total annual runoff 7645.512m3 and cuts runoff by39.7%, current with LID/BMP facilitiesscenario can reducepeak flow0.4528m3/s and cuts peak flow by 35.6%.TN, TP, COD and TSS load of runoffdecrease 2.1 Kg/yr, 0.84Kg/yr,544.3Kg/yrand1232Kg/yrrespectively,Compared to current without LID/BMP facilitiesscenario, it has a51.7%, 55.3%, 52.2% and 58.7% reduction respectively.The scheme of LID/BMPfacilitieshas a certain effectabout the reduction of rainfall runoff and pollution loadin Qingwanjiayuan residential area, the total annual runoff reduction rate range between 25 to 40%.The implementation scheme has a 39.7%runoff reduction rate and its engineering cost is about 2.15 million yuan.So it is belong to a certain cost- benefit scheme.