Evaluation Of Drainage Capacity Of LID Schemes Based On SWMM Model

"Sponge city" has gradually become an unique concept of urban development in China,and low impact development(LID),as an effective and scientific method,has gradually been applied to the construction of urban in China.There are significantly advantages of LID compared with the traditional rainwater storage facilities.However,there were few papers to compare and analyze the two schemesTherefore,this paper takes an university in Shenzhen of water block as the research object,SWMM model was used to model the development status,and the green roof,permeable pavement,rain garden and rainwater storage tank are evaluated.Three main results were revealed in this paper: First,From the total emission reduction effect,when return period of rainfall is 2~50 years,rain garden > permeable pavement > green roof;Secend,From the discharge peak flow reduction effect,when return period of rainfall is 2~50 years,the rain garden > green roof > permeable pavement;Third,from the reduction of runoff coefficient,when return period of rainfall is 2~50 years,permeable pavement >green roof> rain garden;4,Under the same return period of rainfall,the storage capacity of the central storage tank is smaller than that of the terminal storage tank.Considering the cost,land use of storage tank and other factors,it should be located in the middle of the pipe networkThree kinds of LID measures(rain garden,permeable pavement,green roof)were combined with different construction ratios to form 12 schemes,which were added to the current SWMM hydraulic model.And in the following 3 conditions,the 12 schemes was analysis(First,the external rainwater discharge of construction area is not more than the level of undevelopment under the rainfall condition of 2 years 24 hours.Secend,runoff coefficient is less than 0.6 under the rainfall condition of 10 years 24 hours.Third,when the area is built by LID facility,surface water depth is less than 15 cm in 50 years rainfall conditions.).According to the simulation results,finally obtains the four schemes meets the design goal,respectively,green roof(100%)+ permeable pavement(100%),green roof(100%)+ permeable pavement(100%)+ rain garden(10%).green roof(80%)+ permeable pavement(100%)+ rain garden(8%).green roof(80%)+ permeable pavement(100%)+ rain garden(6%).Finally,from the hydrological flood control benefits,life cycle costs and social benefits,the above four qualified schemes and the traditional rainwater storage tank are compared.And the analytic hierarchy process(AHP)was to establish the judgment matrix for effectiveness analysis,The results revealed that,the rainwater reservoir has good hydrological flood control benefits,but considering the cost of inputs,the social benefits,LID schemes has obvious advantages.Their effectiveness on flood control,cost investment and social benefit are compared synthetically.Comparing the comprehensive energy efficiency value of all schemes,it is found that each scheme of LID facility is bigger than the traditional rainwater storage tank,which fully showed the advantages of the LID reconstruction schemes.