Study On The Optimization Of Low Impact Development Facilities In Xining Based On The Analysis Of Engineering Cost And Benefits Of Stormwater Management

After a large number of pilot city construction and theoretical research,China's sponge city construction has entered a stage acceptance period.It is urgent to summarize the existing construction experience and formulate construction and management standards of sponge city with a clear regional targeted,and think about how to rationalize costs,maximize benefits and avoid the blindness of LID facilities.Therefore,this paper focuses on Xi Ning,which has regional characteristics of the northwest region,taking local sponge projects as research samples as well commonly used LID facilities as research objects.This paper studies on the engineering cost,storm stormwater management benefits and cost-efficiency ratio of the facilities through field research,data collection and software simulation.And then,statistical methods are used to process and analyze data.The reaerach hopes to provide the standard reference value of cost and benefit of LID facilities as well as the optimization guidance of facility types,structural practices and monomer scale for future sponge project design of Xi Ning.In addition,the paper also constructs the optimization research method of lid facilities based on the analysis of engineering cost and benefits of stormwater management.The research objects of this paper include permeable facilities(sunken green space,rain garden,biological retention zone,permeable pavement),transmissive facilities(grassed swale)and storage facilities(reservoir),facility name + number refers to facilities with different structural practices.The sample project types include building,residential area and urban road.The quantization of the relationship between cost and benefit is based on the cost-effectiveness ratio.The research technology platform includes SWMM model,Guanglianda,stata and so on.Based on the comparative study of the obtained data,the author believes that,among the commonly used LID facilities in Xining City,the rain garden ? and the biological retention zone ? are the lowest cost permeable facilities for stormwater treatment in Xi Ning.The reference values of the cost-efficiency ratio of these facilities are 130.65 yuan /m3 and 180.93 yuan/m3.Besides,annual stormwater treatment capacity per unit area of these facilities are more than 2m3,make them the preferred facilities in the building and residential area type projects under normal conditions.The cost-efficiency ratio of the permeable pavement including the drainage layer is 275.88 yuan/m3,which is a moderate-cost permeable LID facility.The permeable pavement which is only modified by the surface layer can not basically play the role of stormwater management,whose annual rainwater treatment volume is less than 0.01 m3/m2.The cost reference values of the two grassed swales are respectively 44.80 and 54.37 yuan/m2,which are the cheapest LID facilities.Generally,the cost of reservoir is relatively high,however,if the utilization frequency of stored rainwater can be ensured,the cost-effectiveness ratio can be controlled below 300 yuan/m3 makes which a kind of facility with reasonable cost and can be selected according to actual conditions.The scale of all kinds of facilities should be adjusted within the range of the section according to the law of cost and benefit.By comprehensively comparing the cost and benefit values of various facilities,the projects in building and residential areas in Xi Ning are more suitable to develop sponge construction,while the sponge reconstruction of urban road projects is relatively uneconomical.In addition,the cost-efficiency ratio of this paper only reflects the cost of stormwater treatment under the condition of one-year use of the facility,and the actual application of the reference value needs to be adjusted according to the service life of the facility.