Study On Calculation And Reduction Measures Of Urban Non-point Source Pollution Load

With the rapid economic growth in China in recent years,the process of urbanization has further accelerated,but the environmental pollution problems that accompany it have become increasingly serious.Among them,urban non-point source pollution represented by urban stormwater runoff pollution has become the main reason for polluting urban natural water bodies and endangering urban water ecology.Among the many research contents of urban nonpoint source pollution,the calculation of non-point source pollution load is an important part of non-point source pollution research.How to quickly and accurately calculate the non-point source pollution load in the treatment area plays an important role in the determination of subsequent reduction indicators and the formulation of reduction plans.This article takes the Wangjiangou Basin in Hefei as an example,and first uses the Washington Commission mathematical model to estimate the pollutant load in the Wangjiangou Basin.Then,two typical small areas in the watershed were selected to establish a dynamic model of urban stormwater runoff respectively,and the pollutant load was simulated and used as a basis to evaluate the feasibility of the Washington Commission mathematical model in Hefei.Finally,low-impact development facilities were set up under several common recurring rain types to compare the pollutant load reduction efficiency before and after the installation.The main results are as follows:(1)The Washington Commission method was used to calculate the pollution load per unit area of the four main service areas in the Wangjiangou Basin.According to the calculation results,the severity of the pollution was commercial areas> transportation areas> industrial areas> residential areas;After the area is calculated,the total pollution load of each service type area is calculated and accumulated to obtain the average annual load of Wangjiangou,which is about,tons of COD is 2416,tons of TN is 73,and.tons of TP is 12.9.(2)Establish dynamic models of urban storm rainfall runoff in two typical small areas in the Wangjiangou watershed.After adjusting the parameters of the model through two actual rainfall data,the simulated runoff peak and pollutant peak deviations are less than %,which proves that Reliability of the model.The calculation of the single rainfall pollution load of these two rainfalls was calculated using model calculations and the Washington Committee method.The deviation of the calculation results in the rainwater subdivision of the Feicui Lake Yingbin Hotel,which is mainly a residential area,is within %,while in the industrial area,The deviation of the calculation results in the rain and moisture area of the main Zishi Road was more than %.So we have come to the conclusion that the Washington Commission method calculates more accurately in urban living areas than in industrial areas.(3)Design common recurrence periods such as 0.5a,1a,2a,and 3a.After referring to relevant literature,carry out large-scale reconstruction design simulations of living areas in Wangjiangou Basin.The simulation shows that the pollutant reduction rate decreases as the recurrence period increases.It is small and tends to be gentle;the residential quarters are divided into two types of residential quarters,A and B,and the reduction efficiency under different repetition periods is calculated.The calculation results show that the reduction rate of type A cells is greater than that of type B cells.(4)Arrange the initial rainwater storage tanks in the industrial zone of Wangjiangou watershed to reduce the non-point source pollution load.The simulations were carried out using two methods of joint construction and sub-construction,and the results showed that the reduction rate of the rainwater storage tank in the initial stage of the joint construction was greater than the sub-construction type.Figure [23] table[46] reference[77]...