Abstract
Water and energy resources are interdependent, yet their sustainable synergy remains understudied. Using China's 2016-2020 provincial data, this study employs a dynamic two-stage SBM model to assess the sustainable development efficiency of water resources and regional disparities, with energy poverty incorporated as an exogenous variable. Findings reveal: (1) Water-scarce regions achieve higher efficiency due to strict policies and technological innovation, whereas water-rich areas face a "resource curse". (2) Most provinces exhibit "high production-low sustainability", indicating development prioritization over conservation. (3) In the east, high energy dependence causes a significant drop in TGR of water sustainability when energy poverty is factored in, widening the efficiency gap. In contrast, in central and western regions, particularly western provinces, TGR rises with the inclusion of energy poverty, supported by stringent ecological policies. Finally, targeted countermeasures are proposed: promoting water-saving technologies and new energy applications in the eastern region; strengthening green manufacturing and eco-compensation in the central region; and developing eco-industries and technological innovations in the western region.