Critical Source Area identification of Agricultural Non-point Source Pollution in Xingkai-Lake watershed

The paper achieved identifying the Agricultural Non-point Source Pollution Critical Source Area in Xingkai Lake watershed using pollution index method with the help of RS and GIS. The conclusions were that: (1) the high pollution risk area mainly clustered in the border of ZhiYi, Baipaozi, Xingkaihu and Liumao Towns and the west southern area of Yangmu Town, and the serious soil erosion and high livestock pollution and fertilizer pollution took the main responsibility. (2) The moderate pollution risk distributed in the most of the study area and the high livestock pollution and fertilizer pollution were the reason. (3) The low pollution area located in the south of Farm 857 and the most of Farm Xingkai-hu. The terrain there was quite low and it was the pool for the surrounding area. So it would still threaten the lake under the heavy rainfall.The results revealed that the RS and GIS technology could improve the APPI method accuracy and make the model be in line with the mechanism of the occurrence and migration of the agricultural non-point source pollutants, thus it improved the applicability of the APPI method and could identified the critical source area more quickly and accurately.