Integrated strategies for water sustainability in the Yellow River Basin: Roles of water transfer, reclaimed water, and irrigation efficiency

Water scarcity poses a critical challenge to achieving Sustainable Development Goal 6 (SDG 6), especially in arid and semi-arid regions where agricultural production and food security are highly vulnerable to water deficits. The Yellow River Basin (YRB) in China is particularly affected, with severe water scarcity driven by rapid socio-economic development and climate change. Integrated strategies, such as inter-basin water transfer (IBWT) projects, reclaimed water (RW) utilization, and improvements in irrigation efficiency, are essential to balance competing demands for water resources while safeguarding agricultural sustainability, yet their combined impact remains unclear. This study conducts a holistic evaluation of water scarcity in the YRB by integrating hydrological modelling with various socio-economic data to quantify supply- and demand-side measures from 2005 to 2040. Although IBWT projects have expanded rapidly since 2010, their net impact at the basin scale is negative. In 2020, water exports from the YRB (−1.1 km³) exceeded imports (0.4 km³), yielding a net deficit of −0.7 km³ and indicating that aggravating effects outweigh benefits. In contrast, RW utilization has steadily increased, contributing 3 % to scarcity mitigation by 2020. Future projections for the 2030 s indicate continued water scarcity escalation. However, a 15.2 % reduction is achievable through integrated strategies, with improved irrigation efficiency (8.5 %) serving as the most effective measure, followed by RW utilization (5 %). While IBWT projects contribute least to overall reduction (1.7 %), they play a critical role in addressing regional inequality of water scarcity. These findings underscore the critical role of agricultural water use efficiency and multi-resource synergies in mitigating water scarcity and ensuring food security, particularly in response to growing agricultural demand in the YRB's downstream areas. • By 2020, reclaimed water cut water scarcity by 3 %, with greater future potential. • Water scarcity will worsen in the 2030 s, but mitigation can reduce it by 15.2 %. • Irrigation efficiency improvements serving as the most effective measure (8.5 %). • Water transfer projects reduce scarcity by only 1.7 % but ease regional inequality.