Assessing and Optimizing Sustainable Water–Energy–Food Nexus Security in the Yellow River Basin: A Focus on Water Allocation

Abstract The interplay of population growth, climate change, and urbanization poses significant risks to the water–energy–food (WEF) nexus. This study investigates the security challenges and optimization strategies of the WEF nexus from 2015 to 2022 in China’s Yellow River Basin, a critical production base facing severe water constraints. A water footprint analysis reveals pronounced spatial inequalities, characterized by increasing water consumption for energy and declining use for food. Although the overall nexus security remains relatively stable, water resources, as represented by blue water availability and sectoral demand, inherently pose the greatest risk to regional stability. A nonlinear programming model, solved by sequential quadratic programming (SQP) following Monte Carlo-based initial-point screening, produces two optimization schemes—Nash and Rawlsian–Nash—to enhance basin security. Both strategies suggest reallocating water resources from the agricultural to the energy sector. Specifically, the Nash scheme produces a mean annual percentage change of + 7.18 % in the WEF nexus security index, whereas the equity-prioritizing Rawlsian–Nash scheme lowers overall WEF nexus security while producing a mean annual percentage change of + 0.69 % in the water resources security index. By combining water footprint analysis with equity-constrained optimization, this research provides a quantitative framework for balancing resource efficiency and sectoral security in water-scarce regions.