Estimation Of Agricultural Non-point Source Pollution Load In Haihe River Basin Based On InVEST Model

With the effective control of point source pollution,agricultural non-point source pollution has become a major cause of deterioration of water quality in lakes or basins in China due to its difficult monitoring,strong concealment,wide range of transmission,and high risk.It not only damages regional ecosystems,but also It poses a serious threat to the quality and safety of agricultural products,sustainable development of agriculture and even human health.Therefore,it is of great practical significance to study agricultural non-point source pollution in typical watersheds.This paper takes Haihe River Basin as the research area,combines InVEST model with GIS technology,and uses meteorological data,land use type,DEM,statistical data,etc.to simulate the spatial distribution of nitrogen and phosphorus output load in the basin in 2015,combined with ARCGIS and GeoDA software.The nitrogen and phosphorus load was analyzed spatially,and the relationship between each impact factor and the pollutant output load was further explored.Finally,different scenarios were established to provide suggestions for the prevention and control of agricultural non-point source pollution.The research results are as follows:(1)Quantitative estimation of watershed pollutant load using a modified NDR model.The results show that the basin The spatial distribution of nitrogen and phosphorus output loads is different.The nitrogen and phosphorus loads generated by land use types were 52642943.74 kg and 10467712.32 kg,respectively.The nitrogen and phosphorus loads generated by the farmland non-point source pollution matching model were 34934309.20 kg and 8076608.01 kg,respectively.(2)Hot spot analysis of pollutant load based on ARCGIS.The results show that the nitrogen hotspots and cold spots in the land use types are distributed in the central plain and the northern mountainous areas respectively;while the phosphate hotspots are concentrated in the south and the cold spots are concentrated around the Bohai Bay.The hot spots of nitrogen and phosphorus fertilizers produced by farmland non-point source pollution patterns are distributed in the south of the basin,and the cold spots are distributed in the western part of the basin and near the Bohai Bay.(3)Spatial autocorrelation analysis of pollutant load based on GeoDA software.The global moran'I>0.5 of the nitrogen and phosphorus output load under land use type and farmland non-point source pollution mode indicates that there is a positive correlation in space,and the spatial autocorrelation distribution is spatially different.(4)The output of pollutants in dry land is the most,and the forestry and grassland have strong filtration capacity and less pollutant output.The pollutant load of two crops is greater than the pollutant load of one crop,and the pollutant load of vegetables is greater than other.The pollutant load of two crops increased;the pollutant load of the basin increased with the increase of rainfall;the pollutant load of slope farmland was larger than that of the plain area;the application amount of farmland fertilizer was directly proportional to the pollutant load.(5)Reducing the amount of fertilizer applied to the farmland can greatly reduce the output of pollutants in the basin,and at the same time construct a river bank buffer within a certain range near the water system,which can also reduce the generation of pollutants.