Abstract: In recent years, SWAT (Soil and Water Assessment Tool) model has achieved good application result in humid south China,but in arid river basins in lack of hydrological data, it has not been widely used. In this research, the semi-arid Yanhe River Basin in Shaanxi Province was taken as an example.In association with GIS and RS technology, a hydrological model based on SWAT model for Yanhe River Basin was built. Data series from 1980 to 1985 were used to calibrate the SWAT model and data from 1986 to 1989 were employed to validate the model. The results are as follows: values of Nash-Sutcliffe coefficient and correlation coefficient are 0.644 and 0.832 respectively in calibration period, and 0.630 and 0.872 in validation period, meeting the requirements of model simulation. The results indicate that SWAT model well reflects the monthly runoff hydrologic process in Yanhe River Basin. The research offers a basis for the further application of SWAT model to river basins in the loess plateau of China.

Key words: SWAT model, monthly runoff simulation, Yanhe River Basin, loess plateau, applicability, sensitivity analysis