Land use pattern optimization based on CLUE-S and SWAT models for agricultural non-point source pollution control

Improper land use is one major cause of non-point source pollution. Integrated modeling would support the evaluation and optimization of land use for the non-point source pollution control. In this study, the CLUE-S (the Conversion of Land Use and its Effect at Small regional extent) and SWAT (Soil and Water Assessment Tool) models were coupled to simulate pollution loads under different land use scenarios in the upstream watershed of Miyun Reservoir in Beijing, China. The results indicated that changes in land use structure and pattern under different land use scenarios have significantly affected the non-point source pollution load. The increase of orchards and loss of forest cover has led to an increase in the potential pollution loads of nitrogen by 5.27% and phosphorus by 4.03%. However, in the agricultural non-point source pollution control scenario, pollution loads of nitrogen decreased by 13.94% and phosphorus by 9.86%, resulting from the establishment of riparian vegetation buffers and restoring forest on unutilized land and slope arable land. Coupling the hydrological model SWAT and the land use model CLUE-S succeeded in evaluating the land use pattern for agricultural non-point source pollution control. The coupling of two models provides a new approach for land use optimization towards non-point source pollution control.