Analysis Of Influencing Factors Of Non-point Source Pollution And Evaluation Of Prevention And Control Effects Of The Sihe River Basin

With the rapid development of the economy and the acceleration of the urbanization process,the environmental pollution problems in the river basin have surfaced.Due to the wide spread of surface source pollution and the lack of fixed outfalls and monitoring data,a series of problems have posed a serious threat to water quality safety.In this study,the SWAT model is used to estimate the total TN and TP load of surface pollution in the Sihe River basin,analyze its spatial and temporal distribution characteristics,explore the factors influencing the TN and TP of surface pollution in the basin,identify key source areas,and evaluate the reduction effect and cost-effectiveness of different control measures on the total TN and TP load of surface pollution,and screen out the best control measures in the Sihe River basin,so as to provide some suggestions for the management and control of surface pollution in the Sihe River basin.This study provides a theoretical basis for the management and control of surface source pollution in the Sihe River Basin.The main results of this study are.(1)Analysis of non-point source pollution sources in the river basin:The TN and TP loads of non-point source pollution in the Sihe River Basin mainly come from non-point source pollution.Among them,the contribution rate of chemical fertilizer application to non-point source pollution is the highest,followed by livestock and poultry breeding,and the contribution rate of rural residents’production and domestic sewage discharge is the lowest.(2)Construction of SWAT model:The data required for the SWAT model were collected and organized,and the Sihe River basin was divided into 45 sub-basins and 519 HRUs.the SWAT-CUP model was used to analyze and filter the sensitivity parameters,and the model was calibrated according to the measured hydrological and water quality data from the Shuyuan hydrological station.the R~2 and NSE evaluation indexes all met the requirements.The SWAT model has good applicability in the Sihe River basin and can be used to estimate the TN and TP loads of surface pollution in the basin.(3)Analysis of surface source pollution in the basin:The annual surface source pollution TN and TP loads in the basin are mainly concentrated in June-September,and the rest of the months show a decreasing trend with the decrease of precipitation;the inter-annual variation of surface source loads is small;the surface source pollution TN and TP loads are mainly distributed near the main road of Sihe River;the surface source pollution TN and TP loads in the basin are closely related to the precipitation and the condition of the sub-basin of the basin.(4)Assessment of the reduction effect and cost-effectiveness of different prevention and control measures:the vegetation buffer zone has the best reduction effect on TN and TP loads of surface pollution,with the best setting width of 5m;the fertilizer reduction has the lowest reduction efficiency of surface pollution.The combined prevention and control measures have better reduction effect on TN and TP of the opposite source pollution than individual prevention and control measures.The vegetation buffer zone,grassed river channel and the reforestation of slopes above 15°belong to the prevention and control measures with high reduction efficiency and good environmental benefits to the watershed surface source pollution.These three prevention and control measures can be given priority in the management and control of surface source pollution load in Sihe River watershed.