Research On Simulation And Optimization Of Sponge City Hydrological Process Based On SWC Model

With the rapid development of the urbanization process,the city also faces a series of environmental problems such as waterlogging,surface subsidence,and large-area surface runoff.In order to solve these related problems,the construction technology called sponge urbanization,has emerged.Sponge City construction technology can not only collect rainwater like a sponge,but also purify and store rainwater resources rea-sonably and use it at the time of demand.In order to give full play to the functions of the reducing rainwater and improving the ecological environment of Sponge City,the measurement of water seepage capacity and the optimization of various facilities have become the key of sponge city’s construction technology.Due to the different hydro-logical environments of the construction sites,the research and analysis of the seepage capacity for construction site,the hydrological process simulation,and the comparison of applicable facilities have become the key to the construction of the sponge-based urbanization technology.The main research contents and results of this paper are as follows:(1)Using the variable head test,the seepage coefficient at the experimental site was measured to be 278.27 ml/min and the bare soil seepage coefficient was 321 ml/min.The correlation between seepage coefficient and hydraulic slope is not significant.Hy-draulic slope is the main reason for runoff;seepage coefficient decreases gradually with increasing air humidity,and the seepage coefficient reaches a minimum value of 266.525ml/min in rainy days.The coefficient also reaches a minimum of 286.67 ml/min.After adopting the ecological permeable bricks to reconstruct the permeable pavement,the seepage coefficient of the pavement reached 446.33 ml/min.(2)The SWC model is used to calculate the water stopping capacity of the ex-perimental site and the results were obtained:In the original state,58%of rainfall flows out of the plot through runoff,7%of rainfall evaporates through changes in temperature,and plants and permeable areas inside the plot absorb 35%of rainfall.(3)After taking the city of Chengdu as a construction site to analyze and compare the rainwater utilization of various low-impact development(LID)facilities,they con-cluded:The rainwater garden facilities have the best use of rainwater,with 45%of the annual rainfall infiltration,15.2%of the annual rainfall evaporating,and 39.8%of the annual rainfall generating runoff.(4)Compared with the rainwater utilization situation of various optimization schemes using the SWC model,we can see that the use of pervious paving with eco-logical permeable bricks can reduce the rainfall runoff of the community by about 20%;After the urbanization of the sponge,the annual runoff of the community is reduc-ing from 651.764mm to 491.236mm,the annual runoff has reduced by approximately 25%,the average annual runoff days decreased by five days,and the stagnant flow of rainwater increased from the original 35.052mm to 45.16mm.After the comparison of economic costs and actual rainwater utilization,the most reasonable way to reform the community is to use permeable paving.