Contributions of climatic and social factors to two water use efficiency indicators in the Yellow River

Abstract

Tracing the spatiotemporal tendency and driving forces of water use efficiency (WUE) is of great significance for understanding the carbon‐water balance, especially in large river basins. The lack of differential comparisons regarding the tendencies and driving forces of WUE indicators between the upper and lower reaches of rivers often affects the collaborative allocation and utilization of water resources at the basin scale, especially social factors such as population and economy distributions. Using remote sensing data and hierarchical decomposition methods, we identified the spatiotemporal distribution of the WUE of ecosystems (WUEe) and the WUE of canopies (WUEc) in the Yellow River Basin from 2003 to 2017 as well as the contribution rates of climatic and social factors to WUEe and WUEc. Our results show that WUEe had a different distribution pattern than WUEc. An increase in WUEe was accompanied by a decrease in WUEc, and these changes varied among the upper, middle and lower reaches. WUEc was most negatively correlated with pressure (| r | = 0.65), while WUEe was most positively correlated with the precipitation rate (| r | = 0.68). The contribution rates of climatic factors to both WUEc and WUEe in the upper reaches were higher than 95%. The middle reaches were mainly driven by climatic factors, with contribution rates higher than 90%. In the lower reaches, the contribution rates of social factors to WUEe were higher than 30%. These differentiated contributions indicated the importance of considering social factors in the lower reaches than in the upper reaches when managing WUEe under the dominance of climatic factors on WUEc.