Spatiotemporal evolution and driving mechanisms of agricultural grey water footprint efficiency in the Yangtze River Basin

Abstract

Agricultural non-point source pollution, as reflected by the agricultural grey water footprint (AGWF), poses a significant threat to aquatic ecosystems, agricultural sustainability, and human well-being in the Yangtze River Basin (YRB). However, a systematic understanding of the long-term spatiotemporal evolution, spatial dependence, and formation mechanisms of agricultural grey water footprint efficiency (AGWFE) across the entire basin remains limited. This study develops an integrated analytical framework that combines AGWF accounting, efficiency measurement, exploratory spatial data analysis (ESDA) and GeoDetector analysis. Based on panel data from 19 provinces-level regions in the YRB from 2000 to 2020, we systematically examine the temporal evolution, spatial clustering, spatial differentiation characteristics, and driving mechanisms of AGWFE. The results show that the AGWF exhibited an overall fluctuating downward trend during the study period, whereas the AGWFE followed a fluctuating increase trend. Significant spatial heterogeneity and spatial dependence were observed. High—high clusters of AGWFE were mainly concentrated in the downstream areas of the YRB, while low–low clusters were primarily distributed in the Qinghai–Tibet region and western China. Population and agricultural water consumption were identified as the major factors explaining the spatial differentiation of AGWFE. Moreover, the interaction between sociodemographic factors and basic resource endowment circumstances exhibited stronger explanatory power than individual factors, indicating that the spatial differentiation of AGWFE is jointly shaped by multiple interacting forces. The results indicate that AGWFE is jointly shaped by resource endowment and socioeconomic conditions. These findings provide a scientific basis for optimizing agricultural production structures and formulating differentiated water pollution control policies in the YRB.