SIMULATION OF NON-POINT SOURCE POLLUTION IN ZHUOZHANG RIVER BASIN

Since 1987, the China Government started the “The Water Resource Protection and Management of Hai River Basin” program aimed at tackling the problem of water pollution and realizing the comprehensive control of the ecosystem and water resources in the whole basin. This study aims to model one of the program’s catchments – Zhuozhang River Basin (ZRB), which is a typical area with the striking water scarcity and water quality deterioration in Hai River Basin (HRB). The distributed hydrological model SWAT(Soil and Water Assessment Tool) was used to simulate all related processes affecting water quantity, sediment, and nutrient loads in the catchment using historical flow and meteorological data for 5 years(January 2005December 2009). Data on management practices (crop rotation, planting date, fertilizer quantity and irrigation) were included in the model during the simulation period of 5 years .The main objectives of this study were to evaluate the long-term impact of point source (PS) and nonpoint source (NPS) pollution on water quality loadings and to determine the contribution of point and non-point sources in the entire catchment. Based on the simulated results, the spatiotemporal distributions of flow, sediment and nutrient loads are analyzed; hence the critical areas of soil erosion and nutrient loss were identified, so as to provide the scientific basis for the water resources allocation and pollutant control in the basin.