Enhanced understanding of dominant drivers of Water Yield change across China through the improved attribution analysis framework

The global climate and environment are undergoing rapid changes, impacting hydrological processes through shifts in climate patterns, escalating CO2, and vegetation dynamics. Accurately predicting and quantifying the contribution of these factors to water yield (WY) has become a significant challenge in water resource management and climate adaptation studies. This study proposed an improved WY attribution analysis framework to address the impacts of climate change, vegetation structural change, and CO2-induced physiological change on WY in China. During the study period (1982-2017), changes in climate, vegetation, and CO2 concentrations significantly affected WY, with the magnitude of these impacts varying across different regions. Climate change (especially precipitation change) was found to be the primary driver of WY changes, particularly in the Northwest River Basin, the Southwest River Basin, and parts of the Yangtze River Basin, the Southeast River Basin, and the Pearl River Basin. The vegetation change, including the land cover change and the NDVI change, was the second largest factor influencing WY, especially in central China, where vegetation changes led to a general decrease in runoff. Although the increase in CO2 concentration reduced transpiration by inducing stomatal closure, the effect was relatively small. And it resulted in an overall increase in runoff across China. This study provides important theoretical support for water resource management and offers new perspectives for climate change adaptation strategies, vegetation restoration, and water resource management.