Research And Effect Evaluation Of Campus Sponge Transformation Scheme Based On SWMM

In order to solve the water crisis and improve the water environment,the Ministry of Housing and Urban-Rural Development clearly proposed to speed up the construction of sponge cities in 2014.Campus sponge reconstruction is an important part of sponge city construction.Therefore,through planning,design and construction,it is necessary to systematically manage and control campus rainwater,so that the campus can absorb and release rainwater like a sponge when encountering rain and flood,which is full of "water elasticity" and has the function of self-cleaning.The campus has a high population density and a large demand for water resources,and its construction and transformation have more improvement space.Therefore,it is particularly important to build a campus water circulation system,save water resources,eliminate floods and waterlogging,improve the campus environment and build a beautiful campus landscape.On the basis of summarizing and analyzing the successful cases of sponge city construction and transformation at home and abroad and the research progress of transformation measures,this paper aims at the shortage of campus sponge transformation cases and related research,taking S University in Shaoxing as an example,the sponge transformation scheme is studied and the transformation effect is evaluated based on SWMM.It mainly includes: 1)The function and simulation of seven LID measure modules(permeable pavement,biological detention pond,grass planting ditch,sunken green space,rain bucket,green roof and infiltration ditch)by SWMM are introduced.2)The hydrological status before sponge reconstruction in S university campus in Shaoxing was measured and simulated,and the parameters of SWMM in the campus were calibrated and the reliability of simulation results was verified.3)Based on the SWMM simulation results of the current hydrological situation of S university campus,the goals and ideas of sponge transformation in this campus are analyzed,four transformation schemes are drawn up and SWMM simulation of the transformation effects of various schemes are carried out.4)Based on the simulation results of SWMM before and after campus sponge reconstruction,the effect of sponge reconstruction is further evaluated by AHP.The results show that: 1)The simulation efficiency coefficients of SWMM model reached 0.79 and 0.98 respectively under two different rainfall levels,and the parameters of SWMM model calibrated by manual trial and error method according to the current hydrological conditions are more accurate,so the SWMM model can be used for hydrological simulation analysis before and after sponge reconstruction in the campus.2)Before campus sponge reconstruction,with the increase of rainfall recurrence period,rainwater infiltration,surface runoff,surface water storage and accumulated water points all increase.When rainfall occurs once a year,there will be long-term accumulated water in some road sections,which indicates that the drainage pipe network of campus often accumulated water has low resistance.In order to improve rainwater infiltration and surface water storage,reduce peak runoff and delay peak time,sponge reconstruction should be carried out in campus often accumulated water areas.3)After the reconstruction of the campus sponge body,no matter which plan is adopted,the rainfall infiltration and the surface runoff reduction rate after the reconstruction are obviously increased,scheme 4(adopting pervious paving,sinking greenbelt,biological detention tank,rainwater bucket and multi-combination measures of infiltration ditch)has the strongest infiltration capacity and the largest reduction rate of runoff,it can effectively reduce the waterlogging degree of the campus under the heavy rainfall.4)Retrofit scheme 3(using permeable pavement and subsided green dual combination measures)and scheme 4,total annual runoff control rates were 83.21% and 95% respectively,the plan three and four S college campus reconstruction of sponge meet Zhejiang sponge long-dated goal total annual runoff control more than 75% of the requirements,S effect of cavernous transformation of colleges and universities,The scheme has the best effect of controlling the total amount of runoff in four years.5)The evaluation results of analytic hierarchy process show that the campus sponge transformation schemes proposed in this paper are effective.