The Research Of Non-point Source Pollution In Shayinghe Upstream Based On SWAT Model

At present, China’s water pollution situation is very serious. With point source pollution has been gradually controlled, the non-point source pollution of water has become an important reason for water environment deteriorate and lake eutrophication. So quantification of the non-point source pollution is important for the environment protection.On the basis of "Huaihe River Basin major rivers and lakes water function area water quality compliance evaluation", selected Shayinghe upstream whose rate of reaching the standard was lowest was the study area, using SWAT to simulate and assess spatial and temporal changes of non-point source pollution of Shayinghe upstream, then analyze the main sources of pollution in the watershed to provide reference for non-point source pollution control and management in the river basin. The main research results were as follows:(1) The establishment of a non-point source pollution load model applied to the Shayinghe upstream. Integrating topography, land use, soil type, dam scheduling in the study area, the model calibration and verification of regional runoff process and non-point source pollution loads was completed. The results showed that, the coefficient of determination R2, Nash-Suttcliffe Ens and relative error Re of simulated flow and pollutants met the requirement of the precision of the SWAT model.(2)The non-point source pollution load of the runoff process in Shayinghe upstream was simulated and evaluated. In 2007, the annual runoff and the total annual yield of ammonia of Zhoukou section in Shayinghe upstream was 3.13 billion m3/s and 108516kg. In 2008, the annual runoff and the total annual yield of ammonia of Zhoukou section in Shayinghe upstream was 1.93 billion m3 and 108516kg. From 2007 to 2008, the total annual average yield of ammonia of Zhoukou section in Shayinghe upstream was 116267.5kg, among which total annual average yield of ammonia from the non-point source pollution was 5946.6kg and accounting for 5.1% of the total annual average yield of ammonia. In this case we can draw the conclusion that the ammonia in Shayinghe upstream is mainly contributed by point source pollution.(3) The spatial distribution of non-point source pollution load in Shayinghe upstream was simulated. From 2007 to 2008, the annual basis total nitrogen yield per unit area was 5-30 kg/ha in Shayinghe upstream, therein Weishi, eastern Zhongmou, northern Fugou, central Yuzhou, central Yanling, easten Fugou, southen Xiangcheng, southen Zhoukou and Yancheng were with the highest annual basis TN output per unit area, about 25-30kg/ha. From 2007 to 2008, the average annual total phosphorus per unit area was 0.5-5kg/ha in Shayinghe upstream, among which Xuchang City, central Linying, Yanling, easten Fugou, westen Xiangcheng, southen Zhoukou City and Yancheng were with the highest average annual total phosphorus per unit area, about 3-5kg/ha.(4)The influence factors of nonpoint source pollution load distribution in Shayinghe upstream was analyzed. The rainfall, runoff and the land use had agreat impact on output of non-point source pollution load. The rainfall and runoff were positively related to the ammonia load of the watercourse. The correlation coefficient of rainfall and ammonia load was 0.52, and the correlation coefficient of runoff and ammonia load was 0.74. Among various land use, the output of non-point source pollution load were positively related to the arable land area but were negatively correlated to the forest land area, which revealed the greater influence of human activity on the output of non-point source pollution load.