Key Technology And Theory Research On Pollution Control Of Sponge City

With the accelerating process of urbanization,the surface runoff pollution is more and more serious.If any rainwater runoff is drained into the water at random,it will inevitably have a greater impact on urban water bodies.Therefore,if the rainfall runoff can be managed and controlled,it can not only effectively relieve the urban waterlogging but also reduce the pollution load of urban runoff,which is also of great significance to the economy,society and ecology.In this paper,the drainage network of Lujia River and its service area in Chaohu City was selected as the research object.SWMM model was constructed to study the effect of source control measures such as permeable pavement,bioretention cell pool and rainwater garden on the reduction of pollutants in runoff,And the variation of pollutant removal rate and interception rate under the condition of precipitation duration,recurrence period and source control measures of the intercepting diversion system,and the economically optimal interception volume is determined by taking Lu Jiahe pollutant capacity as the constraint condition.In the calculation analysis of river pollutant carrying capacity,the principle of different river water models and the applicable conditions are analyzed,a calculation model for determining the use of one-dimensional river pollutant carrying capacity,and to determine the relevant parameters in the calculation of IV water quality standard,Lu Jia He COD assimilative capacity for 17.739t/a TP assimilative capacity for 0.508 t/a,TN assimilative capacity for 0.164t/a.When the SWMM model is built,the terrain,the direction of the pipe network,the type of land use and so on are considered.Chaohu City generated different return period rainfall line using the Chicago rain type;surface runoff and the convergence process by infiltration model and nonlinear model of Green-Ampt reservoir;saturation function and exponential function with surface pollutant accumulation and erosion model;dynamic wave transmission model using simulated rain pipe network;water quality attenuation using the first-order decay model.Complete the generalizability of the study area model.On this basis,the spongy city measures were added to the analysis of the SWMM simulation results,and the results were as follows:(1)The rainfall intensity has a significant impact on TSS,COD,TN and TP both after urbanization and sponge city measures.The total pollutant load is positively correlated with rainfall intensity.Permeability paving,biological retention pool and rain garden have certain control effect on pollutants.The average removal rates of TSS,COD,TN and TP in the permeable pavement were 61%,59%,47% and 33% respectively in five kinds of reappearance periods.The average removal rates of TSS,COD,TN and TP The average removal rates of TSS,COD,TN and TP in the rainwater garden were basically the same as those in the bioretention tank.The average removal rates were 52%,51%,39% and 32%,respectively.Comprehensive comparison of the three effects on water quality,to determine the order of permeability paving> bioretention cell ≈ rain garden.(2)When considering the pollutant capacity of Lujiahe River as the constraint condition,the cut-off rates for COD,TN and TP under the five-year period of return are respectively 20%,30% and 70% after urbanization;Take 11%,27% and 50% under the paving measures and 14% m,26% and 50% under the bioretention cell measures.