Abstract: Blue-green water evaluation can provide scientific suggestion for the comprehensive management of water resources in the basin. Here Wujiang river basin was as an example, based on the SWAT (Soil and Water Assessment Tool) hydrological model, the annual runoff anomaly percentage method was used to determine different precipitation patterns. The Mann-Kendall trend method(M-K) and the linear regression trend analysis method were applied to evaluate the temporal and spatial characteristics of blue-green water resources from 1992 to 2019 and the differences in the distribution and spatial distribution of blue-green water in different precipitation years. The results showed that: (1) the simulation of the SWAT model was better, which describe the water cycle process in Wujiang river basin. (2) The annual average precipitation, blue water resources and green water resources in the basin were 1126mm, 549mm and 589mm, respectively. The precipitation and blue water resources generally showed a decrease trend, but the green water resources exhibited an increase trend. (3) The green water coefficient were 46%, 52% and 58% in the wet year, normal year and dry year, respectively. Thus, the amount of green water resources has changed and plays an important role in ecosystem maintenance. (4) From the upstream to the downstream of the basin, the precipitation and blue water resources increased first and then decreased, while the green water resources presented a trend of first increasing, then decreasing and finally increasing. (5) The temporal and spatial variation of blue water resources was mainly impacted by the change of precipitation, while that of green water resources was affected by the change of precipitation, temperature, and land use cover.

Key words: SWAT model, Wujiang river basin, Blue water, Green water, Temporal and spatial distribution, Precipitation patterns