Study On Sponge Reconstruction Of Urban Infrastructure Based On SWMM

With the rapid development of the global economy and the continuous expansion of urban scale,urban waterlogging problems have become increasingly prominent,and flood disasters have become a serious obstacle to urban development.Combined with the concept of low-impact development abroad,the construction of ’ sponge city ’ is proposed.Through ’ infiltration,stagnation,storage,purification,use and drainage ’,the rainfall runoff process is controlled and the surface runoff water quality is purified.In view of the above situation,a region of Wuwei City in Wuhu City was selected as the research object,and the rainwater drainage system model based on SWMM was established.Under different return periods of rainfall,the effects of different LID measures on pipe network load,runoff volume and runoff water quality were explored,and the total annual runoff control rate was checked.The simulation model based on SWMM in the study area shows that sponge measures have obvious control effect on the water quantity and quality of rainwater runoff,which provides reference for the reconstruction of sponge cities in similar areas.The main results are as follows.（1）The SWMM model of rainwater drainage system in the study area was constructed,and the hydrological parameters of the model were calibrated and verified by the comprehensive runoff coefficient method to ensure the authenticity and reliability of the model.Taking the total annual runoff control rate of 75 % as the goal,three LID measures are designed combined with the low impact development index,and the sensitivity analysis of LID measures parameters is carried out by using the Morris method.The sensitivity order of LID parameters to the simulated output value is obtained,which provides a reasonable reference for the subsequent parameter values and improves the accuracy of the model.（2）After the introduction of LID measures,under different return period rainfall conditions,the reduction rate of surface runoff reached 26.21 % ～ 52.2 %,and the reduction rate of discharge peak flow reached 25.86 % ～ 54.01 %.The reduction rate of overload pipe section is 24 % ～ 80 %,and the reduction rate of node overflow is 22 % ～77 %.With the increase of rainfall return period,the overloaded canal,node overflow,surface runoff reduction rate and peak flow reduction rate decrease.Among them,the scheme one LID measures combination（permeable pavement,biol-retention cell,green roof,rain garden）has the best effect on runoff control in the study area,and the total annual runoff control rate reaches 80 %.（3）With the increase of rainfall return period,the total amount of pollutants in runoff gradually increases due to the enhanced scouring effect,and the pollutant reduction rate of LID measures is about 45 % ～ 60 %.With the increase of rainfall return period,the reduction rate of pollutants gradually decreases.Increasing rainwater storage facilities can effectively control runoff and reduce pollutants.Under the condition of low return period rainfall,the effect of rainwater storage facilities delaying flood peak is obvious.（4）From the construction area,municipal road,park green space,sunken square,urban water system five kinds of construction projects for sponge transformation demonstration,according to the problems existing in different engineering present situation design specific transformation scheme,the LID measures are implemented.