Spatiotemporal distribution and driving factors of water use efficiency in the Yangtze River Delta urban agglomeration under the background of sustainability

• Revealed the U-shaped trend and spatial hierarchy of water use efficiency. • Confirmed the spatial convergence of water use efficiency across cities. • Identified multi-dimensional driving factors and their interactive effects. As a key economic strategic region in China, the Yangtze River Delta urban agglomeration plays a crucial role in national sustainable development. Exploring the spatiotemporal distribution and influencing factors of water use efficiency (WUE) in this region is of great significance for promoting sustainable water resource utilization. This study employs a comprehensive methodological framework, including the Super-SBM model with undesirable outputs, Moran’s I, Gini coefficient, convergence analysis, geographic detector, and Tobit regression model, to investigate the spatiotemporal characteristics and driving factors of WUE in the Yangtze River Delta (YRD). The results reveal that: (1) The overall trend of WUE in the region follows a “U-shaped” pattern, first declining and then rising, with a spatial hierarchy of Jiangsu (0.737) > Shanghai (0.662) > Anhui (0.631) > Zhejiang (0.608). The difference in hypervariable density is identified as the primary source of regional disparities in WUE. (2) Convergence analysis indicates a significant spatial β -convergence of WUE across cities in the region, suggesting that cities with relatively lower efficiency are gradually narrowing the gap with those performing at higher levels. This is consistent with the findings derived from the Gini coefficient. (3) Economic development and technological innovation significantly promote WUE, while factors such as industrial structure, water resource endowment, waterway transportation, urbanization level, and per capita water consumption exert negative impacts. Moreover, the interaction effects among these factors demonstrate a stronger driving influence on WUE than any single factor alone. The findings of this study not only deepen the understanding of WUE dynamics but also provide valuable insights for formulating strategies to enhance water resource efficiency both in the YRD and across China.