Evaluation of Best Management Practices for non-point source pollution based on the SWAT model in the Hanjiang River Basin, China

Abstract

Abstract Taking the Hanjiang River Basin with the Ankang hydrological station as the control section and as the study area, the Soil and Water Assessment Tool (SWAT) model was used to identify the spatial and temporal distribution of non-point source (NPS) pollution and determine the critical source areas (CSA). We set up 11 Best Management Practices (BMPs) in the CSA and evaluated their environmental and comprehensive benefits. The results showed that TN and TP loads in flood season were significantly higher than that in the non-flood season. The distribution of loss intensity of TN and TP load has a strong correlation with runoff and sediment erosion intensity, respectively. Among the eight individual BMPs, the reduction rates of stubble coverage, grassed waterway and returning farmland to forest land were relatively high, and the comprehensive attribute value Z of stubble coverage was the highest. Among the three combined BMPs, the reduction rate of ‘stubble coverage + grassed waterway + returning farmland to forest land (>25°)’ was the highest and the Z value was the largest. Overall, the BMPs such as stubble coverage, grassed waterway, and returning farmland to forest land can be adopted alternately to control NPS pollution in the Hanjiang River Basin.