Spatiotemporal Dynamics and Attribution Analysis of Blue and Green Water Resources During 1980-2019 in the Hanjiang River Basin, China

A SWAT (soil and water assessment tool) model was built to elucidate the spatiotemporal dynamic changes in blue/green water resources during 1980-2019 in the Hanjiang River Basin, China. Several scenarios were constructed to analyze the spatiotemporal differentiation between green and blue water resources in diverse climate and land utilization conditions. The results showed that (1) the mean blue water and green water resources were 392.24 and 410.48 mm/year; (2) the blue water resources showed a non-significant fluctuating decreasing trend, while the green water resources showed a non-significant increasing trend in volume; (3) the high-value areas of the blue water resources were concentrated in the western, northeastern, and southeastern parts of the Hanjiang River Basin, whereas the western region had more abundant green water resources; (4) compared with the effects of land use change, the climate factors contributed much more to variations in the blue/green water resources of the Hanjiang River Basin. Overall, the blue/green water resources in most areas of the Hanjiang River Basin had a downward trend during 1980-2019. The findings may offer theoretical support for the optimal allocation and management of water resources in the Hanjiang River Basin, China, under climate change.