Research On Design And Comprehensive Benefit Evaluation System For Low Impact Development(LID) Of Urban Stormwater Management Measures

Recently,urban waterlogging occurred in many cities,which causing widespread concern in the community.To address these problems,the "sponge city" program was proposed which can help cities better absorb rain to improve the environment,save water resources and prevent waterlogging.As a new water management measures,low impact development(LID)is a process involving urban runoff control technical measures.It focuses on the control of runoffat the source,and a collection of environmental,ecological,economic comprehensive measures.This paper mainly focused on the design and comprehensive benefit evaluation for low impact development(LID)of urban stormwater management measures.On the basis of domestic and foreign related researchs,a comprehensive summary of widely applicated low impact development(LID)measures was carreied out.A evaluation system for LID measures comprehensive benefit was established combined with storm water management model(SWMM)and Analytic Hierarchy Process(AHP).Taking a certain area of Zaohe River and Chan River in Xi'an city as the study area respectively,the design and comprehensive benefit evaluation of LID measures were implemented to verify the universality of evaluation system The conclusions obtained was as following:(1)A summary on widely applicated low-impact development measures(bioretention system,green roofs,vegetation swales,permeable pavement,low elevation greenbelt,rain barrels,rain pool,infiltration trench,etc.)was carried out from the aspects of its structure,applicable condition,design,selection ofpacking and plants,management and maintenance.(2)On the basis of the status quo,combined with SWMM model and Analytic Hierarchy Process(AHP),a evaluation system for LID measures comprehensive benefit containing environmental benefit,economic benefit and social benefit was carried out.First of all,regional assessments of study area were surposed to be conducted according to the field investigation.Secondly,appropriate LID measures was determined preliminary combining site conditions and usage characteristics of LID measures.Then,comprehensive benefits of select LID measures combined with SWMM model and AHP wer evaluated.Finally,LID combination plans were designed based on the LID single measures with higher comprehensive benefits values,and their comprehensive benefits were evaluated to obtain the optimal LID combination plan.(3)Taking a certain of Zao River in Xi'an as the study area,the SWMM model of study area was constructed.Based on the built evaluation system,the preferential order of LID single measures comprehensive benefit was as follows:rain barrels>bioretention>low elevation greenbelt>green roofs>permeable pavement.Four LID combination plans were designed with bioretention,rain barrels,low elevation greenbelt.The preferential order of LID combination plans was as follows:Plan ?>Plan ?>Plan ?>Plan ?.Plan II(low elevation greenbelt and rain barrels)was the preferred plan.(4)Taking a certain of Chan River as the study area,the SWMM model of study area was constructed.Based on the built evaluation system,the preferential order of LID single measures comprehensive benefit was as follows:bioretention>rain barrels>low elevation greenbelt>green roofs>permeable pavement.Five LID combination plans were designed with bioretention,rain barrels,low elevation greenbelt and green roofs.The preferential order of LID combination plans was as follows:Plan ?>Plan ?>Plan ?>Plan ?>Plan ?.Plan IV(bioretention and green roofs)was optimal LID combination plan.