Countermeasures for agricultural non-point source pollution in Wangjiagou watershed of Chongqing

With regard to the control of agricultural non-point source pollution in Sanxia Reservoir region,Wangjiagou watershed in Chongqing was taken as a study case.Based on the high-resolution satellite remote sensing images by ALOS and WorldView1 and the land use,planting structure and slope distribution information extracted by DEM,the causes and distribution rules of the agricultural non-point source pollution in Wangjiagou watershed were spatially analyzed combined with the its economic,social,hydrological,meteorological,ecological environment data.The control measures were proposed for the domestic pollution in residential area,the runoff pollution in farmlands and the nutrient loss in slope land in Wanjiagou watershed.The results show that the local fragile ecological environment and the irrational land use provide prerequisites for the migration and transformation of pollutants,and the lack of eliminating,reducing and blocking structures is the important factor for the direct input of the pollutants into water.Relevant measures to reduce the pollutants from residential,agricultural runoff and slope land were proposed as follows:(1) construction of centralized domestic sewage and waste project to completely solve domestic pollution in the residential area,(2) popularization of water-fertilizer coupling technology to improve the use efficiency of fertilizers and to reduce the total amount of fertilizers; (3) adoption of protective farmland measures and farmland returning to woodland in slope land to establish effective control system for soil and water and nutrient.