Based On The Control Effect Research Of LID In Non-point Source Pollution

In recent years,the suggestion of sponge urban construction are expedite presented by xi'an city to resolve the urban waterlogg and non-point source pollution disasters.The low impact development rainwater utilization system which the core component of sponge urban construction,It was obviously that LID rainwater utilization system was the most effective method for alleviating urban waterlogging,but the effect of cut urban non-point source pollution was not clear enough.Therefore,Based on the SWMM model,Xi 'an university of Technology,Jin Hua campus was selected as the object of study area in this article,the parameter calibration and verification procedures was completed by two independent rainfall processes.The revised Morris filtering method and GLUE method were carried out respectively to analysed local and global sensitivity of some hydraulic parameters in SWMM model.At last,carried out LID design plan for the study area and contrastive analysis it's effectiveness in urban non-point source pollution problem under different rainfall conditions in the study area.The main conclusions are as follows:(1)The sub catchment area and drainage pipe network was generalized rationally in the studied area.The land use types in the study area was detailed divided and took analysis in pollution source.The SWMM model in the study area was build by measured data.According to the calculated result of model simulated differentiation,the deviation between simulated and measured value in hydraulic and water quality module was respectively satisfied the limit of error as 20% and 25%.With model verified result,the variable coefficient between simulation and actual runoff coefficient in outlet-1 and outlet-2 control area respectively was satisfied the limit of error as ± 5%.In conclusion,the established model has good applicability and prediction precision.(2)According to the local and global sensitivity analysis results of model parameters,the value of Imperv and Con-Mann has great influence on the constructed model,which werehigh sensitivity parameters.With the probability density and cumulative probability density distribution of "acceptable" likelihood value point(NS > 0)in every value interval,the model precision could been significantly improved and the process of parameter calibrated could been simplified in which the value of Imperv and Con-Mann were chosen in(58%,88%)and(0.011,0.013).(3)According to the simulated result of study area by LID planed and designed,with the increased of rainfall return period,the reduce effectiveness of LID measures for the surface runoff pollutants was tend to declined;With the constant increase of rainfall peak coefficient,the reduce effectiveness of LID measures for the surface runoff pollutants was tend to improved,but the improvement was not significant;As the long series of practical rainfall simulation on study area SWMM model,the total surface runoff and the total pollutant load reduction ratio could be reached to 67% and 68% respectively;Develop alternative LID design for the study area,the original design scheme have great effectivness in elimination waterlogging and non-point source pollution for the study area through the comparative analysis,Plan-3 have great effectivness in delay the flood peak and pollutant concentration peak time,the effect of alleviate waterlogging and non-point source pollution in the study area is good too,can be used as the original plan of alternatives.