Abstract: Affected by human activities and major water conservancy projects, the SWAT model has some shortcomings in the calculation of river parameters and average slope length. We use remote sensing technology and empirical formulas to modify the unreasonable parameters. After modifying the parameters, we select parameters that are more sensitive to hydrology and water quality processes and employ SWAT-CUP software to optimize the model. The calibration and verification accuracy are satisfactory. The R² and NS of runoff is 0.764 3-0.967 4 and 0.754 8-0.899 8, respectively, and the R² and NS of total nitrogen load is 0.546 2-0.659 9 and 0.526 8-0.638 8, respectively. The results indicate that given the other parameters unchanged,the present method better reflects the real topography and river channel information in the basin, and also improves the simulation accuracy of the model's monthly runoff. R² increased from 0.834 9 to 0.871 9, and NS increased from 0.698 7 to 0.771 8.

Key words: SWAT, parameter modification, channel parameters, average slope length, remote sensing technology, empirical formulas, Deze reservoir