Assessment of reclaimed water utilization in water-scarce regions of China: A multi-dimensional–multi-agent coupling and nesting perspective

Reclaimed water utilization is a vital strategy for combatting global water scarcity. In China, diverse degrees and types of water scarcity have led to insufficient and unbalanced reclaimed water utilization. To address this problem, this study introduces a novel perspective that considers multi-dimensional (reclaimed water quantity–quality–price) and multi-agent (reclaimed water producers–consumers–government) coupling and nesting to establish a comprehensive framework for evaluating the reclaimed water utilization level (RWUL) in water-scarce regions. This comprehensive framework, comprising theoretical research, model construction, and region selection, is applied to water-scarce regions of China. The findings reveal that the RWUL grades in these regions are generally modest—Grades I to III (lower-level to high-level reclaimed water utilization). The RWUL grades vary based on regional water scarcity combinations. RWUL grades in water-scarce regions characterized by low water quality scarcity (Type C) are lower than those in regions with high water quantity and high water quality scarcity (Type H), low water quantity and high water quality scarcity (Type G), and low water quantity and low water quality (Type D). However, none of these regions achieved Grade IV (higher-level reclaimed water utilization). Consequently, based on the identified main influencing factors of RWUL, this study proposes five region-tailored measures for each water scarcity combination of regions to enhance their RWUL. By offering a comprehensive framework for assessing RWUL in water-scarce regions of China, this study not only identifies the existing shortcomings in reclaimed water utilization but also provides tailored measures for improvement. These insights are essential for policymakers seeking to implement targeted measures that promote reclaimed water utilization in water-scarce regions.