Research On Quantification Of Agricultural Non-point-Source Pollution Of Baseflow And Surface Runoff In The Wangbeng Region Of Huaihe River Basin

Groundwater which is seriously polluted by non-point sources caused by agricultural production activities and residents’ lives is reversely supplied to surface water bodies in the form of basic flow to a certain extent,which makes surface water bodies polluted to a certain extent.Therefore,it is very important to solve the basic flow load problem of non-point source pollutants in the basin.Secondly,accurate quantitative segmentation is the most important problem.In this study,Wangbeng section of Huaihe River Basin was selected as the research object.Based on the investigation of surface water quality in the study area,a pollution model was established by using field monitoring sampling,yearbook data and remote sensing data,which can be applied to this study.The hydrological water quality of Wangbeng section of Huaihe River Basin was continuously simulated to determine the load of non-point source base flow pollution.In the process,the model was corrected several times to achieve the preset goal.Then,the quantitative study of non-point source pollution under the influence of basic flow and surface runoff is analyzed.The main results are as follows:(1)The optimal statistical equation of daily nutrient load is established by using LOADEST model,and the nutrient load of rivers under different time scales(day/month/year)is estimated.The data of this model can be divided into two categories,in which the water quality data is limited and discrete,while the daily flow data is continuous.Using pollution segmentation method,the point source pollution and non-point source pollution are divided,and the load of non-point source pollutants is further estimated.The results show that the monthly loads of NH4+-N,TP,TN and COD simulated by the single-year model are better than those simulated by the multi-year model.The non-point source pollution load of total phosphorus accounts for less than 5.00%of the total load,while the total nitrogen accounts for more than 20%.(2)The Pulse Signal Basic Flow Load Division(PBLD)model is proposed in this paper based on the land use type,soil texture and slope of the study area,and correction factors are proposed based on the previous segmentation model.The fitting degree between the pollutant load of the "measured" base flow date and the corresponding simulated base flow load was compared,and the performance of the model was evaluated by R2 and NS.The results show that the linear regression correlation coefficient between the "measured" ammonia nitrogen and the simulated ammonia nitrogen is 0.93,Nash coefficient is 0.84,and the linear regression correlation coefficient of permanganate index is 0.93 and Nash coefficient is 0.97,which indicates that the PBLD model has high accuracy and is suitable for dividing the load of ammonia nitrogen and permanganate index in the basic flow between Wangbeng section of Huaihe River Basin.(3)Based on slope,land use and soil texture,the variation of base flow pollution load under different time lengths(annual and interannual)was studied,and the non-point source pollution was divided into base flow load and the related quantitative research was carried out.The results show that the segmentation of basic flow pollution load by daily runoff series is better than that by monthly/annual runoff series.However,the results of base flow pollution load segmentation based on monthly/annual runoff series can still reflect the actual pollution load to a certain extent.Figure[34]Table[24]Reference[94]...