Spatio-temporal variability and trend of blue-green water resources in the Kaidu River Basin, an arid region of China

Study region: Kaidu River Basin, an arid region of China Study focus: Water resources are scarce and unstable. Adverse changes in blue-green water resources can disrupt water balance and availability in arid regions. Therefore, it is crucial to effectively assess and predict future blue-green water resources in arid areas. This study utilizes the Soil and Water Assessment Tool (SWAT), Patch-generating Land Use Simulation (PLUS), and Global Circulation Models (GCMs) to analyze the interactive impacts of climate and land use/ cover changes (LUCC) on blue-green water in arid basin from 1990 to 2050. New hydrological insights for the region: This work identified key factors influencing blue-green water changes, including forests, grasslands, and snowmelt. In the historical scenarios, the Kaidu River basin exhibited significant interannual variations in blue water and precipitation. In the future scenarios, blue water increases (+3.6%), and green water decreases (-1.8%) under SSP245 (medium emissions). Under SSP585 (high emissions), blue water decreases (-2.4%), and green water increases (+1.8%). Under SSP126 (low emissions), both blue water (+8.5%) and green water (+0.73%) show an increasing trend. The change in snowmelt is the main reason for the first peak of blue water in April May. Under historical and future snowmelt conditions, blue water shows a significant upward or downward trend with the amount of snowmelt. The findings provided practical hints for the enhancement of the management and allocation of precious water resources.