Measurement and driving mechanisms of water use efficiency in the three major urban agglomerations in China from the perspective of green and sustainable development

• An innovative multi-dimensional indicator system was developed for comprehensive water use efficiency (WUE) evaluation. • Systematic comparison and targeted improvement strategies for WUE among urban agglomerations were conducted and proposed. • The key driving factor for PRDUA is the investment in fixed assets for urban municipal public facilities construction. • The key driving factors for BTHUA are the number of employees at the end of urban non-private units and total water supply. • The three major urban agglomerations experienced an upward WUE trend, despite significant spatiotemporal heterogeneity. Sustainable water use is crucial for economic and social progress. Given the increasing water and energy pressures faced by urban agglomerations, improving water use efficiency (WUE) is essential for achieving regional low-carbon sustainable development. This study uses the Super-SBM model to measure WUE in the Yangtze River Delta Urban Agglomeration (YRDUA), Pearl River Delta Urban Agglomeration (PRDUA), and Beijing-Tianjin-Hebei Urban Agglomeration (BTHUA) from 2009 to 2022, by establishing a multi-dimensional indicator system that encompasses water resources, energy, and industrial structure. Local spatial autocorrelation and systematic clustering methods were employed to analyze their spatial–temporal evolution. The driving mechanisms were identified by the BP-DEMATEL model. Results show: (1) The overall trend of WUE shows an upward trajectory. The average annual growth rates of WUE are 2.4 % for PRDUA, 3.7 % for YRDUA, and 6.8 % for BTHUA. The average WUE follows the order of YRDUA > PRDUA > BTHUA. Specifically, YRDUA has high WUE edges, low middle; BTHUA and PRDUA show “strong center, weak periphery”. (2) Key factors include the number of employees at the end of the period in urban non-private units (NEUNU), the investment in fixed assets for urban municipal public facilities construction (IFAUMC), the total electricity consumption (TEC), and the added value of the secondary industry (AVSI). (3) Notably, the key influencing factors differ among agglomerations: For PRDUA, the key influencing factors are IFAUMC and AVSI; for YRDUA, they are NEUNU, IFAUMC, and the added value of the tertiary industry; for BTHUA, they are NEUNU, the total water supply, and TEC. (4) Cities are classified into three categories (i.e., Tremendous-Input High-Efficiency, High-Input Medium-Efficiency, and General-Input Diverse-Efficiency Water Use Cities) with distinct key factors, according to WUE and input–output indicators. This study, for the first time, adopts a unique multi-dimensional indicator system to compare the similarities and differences in WUE among three major urban agglomerations, providing valuable insights and support for their green, low-carbon, and high-quality development.