Abstract: In order to understand the spatiotemporal pattern difference of blue-green water in typical reference years on a watershed scale, this study selected the Weihe River Basin in northwestern of China to analyze the spatiotemporal distribution pattern difference of blue-green water, and obtained the typical reference years by using standardized precipitation index(SPI) and precipitation anomaly index(Pa). The results showed that: (1)the years of 1983, 1997 and 2007 were determined as wet year, dry year and normal year, respectively. (2)Calibration and validation results showed a similar change trend between simulated and observed discharges, and the SWAT can be used to predict hydrological processes in Weihe River Basin. (3)Change of the green water was relatively stable in the typical reference years, and the green water coefficients were 82.06%, 93.47% and 87.72% in the wet year, dry year and normal year, respectively. (4)Spatially, the blue-green water decreased from southeast to northwest in Weihe River Basin. The spatial distribution of green water indicated that the proportion of green water in the wet year (1983) or areas (southeast) was lower than the normal and dry year (1997) or areas (north).

Key words: SWAT, Blue-green water, Green water coefficient, Weihe River Basin