A Cost-Optimization Model for Water-Scarcity Mitigation Strategies Towards Differentiated City Types in China

Water scarcity has become a major bottleneck to global sustainable development, threatening ecosystem security and socio-economic stability. However, previous studies have failed to distinguish regional characteristics of scarcity and to propose cost-optimal differentiated management strategies. We systematically assessed the scarcity patterns and seasonal dynamics of 350 prefecture-level cities in China during the period 2021–2024, developed a city classification scheme based on scarcity intensity and seasonal variability, and established a least-cost optimization model to identify the optimal management portfolios for different scarcity types. The results show that water pollution significantly exacerbates scarcity intensity and prolongs its duration; the classification framework reveals the complexity and heterogeneity of scarcity across China; and the optimization model demonstrates that even under the widespread implementation of existing measures, further portfolio optimization can still achieve an additional 9.31–69.32% reduction in scarcity under cost-effective conditions. The findings enable decision-makers to develop differentiated and cost-efficient management strategies.