Abstract: The blue and green water resources in the Yangtze River basin (YRB) were simulated by using the GLDAS (Global Land Data Assignment System) Noah hydrological model,and then the distribution of blue and green water resources and their temporal and spatial changes were revealed. Results demonstrate that from 2000 to 2019,the multi-year average blue water resource and green water resource in YRB was 420.24 mm and 686.95 mm,respectively,and the latter was about 1.62 times of the former. Over the past two decades,the blue water resource,green water resource and green water coefficient in the YRB showed insignificant increasing trends,and in particular,the change rate of blue water resource and green water resource was 3.26 mm/a and 2.27 mm/a during 2000-2019,respectively. On monthly scale,the blue and green water resources expanded in July and August,accounting for 29%-32% of the whole year,while shrank in January and February,accounting for 5%-6% of the whole year. On spatial scale,blue water resource distributed in a pattern of higher in the southeast and lower in the northwest,while green water resource higher in the east and lower in the west,and green water coefficient higher in the northwest and lower in the southeast. Scientific and comprehensive evaluation of blue and green water resources can provide scientific basis for optimizing water resources utilization mode and improving water resources utilization efficiency.

Key words: blue water resources, green water resources, GLDAS-NOAH hydrological model, Yangtze River Basin, Spatiotemporal variation characteristic