Study On The Comprehensive Benefits Of Campus Sponge Renovation Under The Background Of Dual-carbon

With the concept of low impact development deeply rooted in people’s mind,it has become an important topic of sponge construction to solve the problems of new and old urban water and improve the urban water environment by using sponge facilities.Campuses are an important part of the city,and sponge campus is also an important link in the development and construction of sponge cities.This paper proposes research questions based on the storm-flood background and carbon peaking and carbon neutrality goals.Five rainfall conditions were designed,and the MIKE series model was used to simulate the campus storm-water management under two different scenarios,and the carbon emission under the low impact development scenario was calculated.The comprehensive benefit evaluation system of sponge campus was constructed,and the optimal design scheme was selected by combining AHP-DEMATEL model comparison.The main conclusions are as follows:(1)Under the current situation,the water transport capacity of the drainage system in the study area is slightly poor.In the low recurrence period(once every two years),the proportion of overloaded pipe sections is 97.31%,and the proportion of overflow nodes is 44%,which indicates that the overflow risk of nodes is high,and the probability of waterlogging occurs in the campus when it encounters heavy rainfall is high.Under different rainfall events,the campus has different degrees of water accumulation.Affected by the drainage capacity of pipe network,pipe network density and the topography,Weishi Road,Duxing Road and areas near the Ethnic restaurant on the campus have serious water accumulation.(2)The four sponge reconstruction schemes has a positive impact on the improving water quantity and quality in the study area.In contrast,Scheme 3(22440 m2 bioretention facility+6040 m2 permeable pavement+6100 m2 green roof+12306 m3 PP module reservoir)has the largest proportion of bioretention facility,the best effect of controlling runoff and environmental load,and the strongest ability to improve pipeline water transmission.Scheme 4(4903 m2 bioretention facility+5100 m2 permeable pavement+25700 m2 green roof+10060 m3 PP module reservoir)has the largest green roof area and the worst effect.Scheme 2(5600 m2 bioretention facility+23500 m2 permeable pavement+5961 m2 green roof+11344 m3 PP module reservoir)permeable pavement occupies the largest proportion and the peak cutting effect is the most prominent.The water quality optimization ability of the design scheme is relatively weak.Under the rainfall condition of 12.775 mm,the control ability of SS is 21.52%-37.57%.(3)In the whole life cycle of sponge campus,the carbon emission in the construction stage accounts for about 50%.Scheme 2 has the highest carbon emission in the construction phase;Scheme 3 has the highest carbon emission in operation and maintenance stage.The order of total carbon emission was Scheme 2>Scheme 1>Scheme 4>Scheme 3.The order of annual carbon sink is:Scheme 4>Scheme 1>Scheme 3>Scheme 2,and carbon neutrality can be achieved after 13 years,26 years,32 years and 52 years.Carbon emissions of sponge modification can be reduced by source emission reduction and process emission reduction.(4)11 evaluation indexes,including construction cost,rainwater reuse,carbon sink capacity,education and publicity,were selected from three perspectives of economy,ecology and functional benefits to construct the comprehensive benefit evaluation index system of Sponge campus.Through AHP-DEMATEL comprehensive method to determine the comprehensive weight of indicators,in which the pipe network load control is the primary key factor affecting the comprehensive benefit.Scheme 4 has the best ecological benefits,functional benefit and comprehensive benefits,so it can be used as the preferred scheme,while Scheme 1 and Scheme 4 have little difference in benefits,so it can be used as an alternative design scheme.