Adaptive water management under coal-fired power phase-out: Reshaping of water supply-demand patterns and new equilibrium for cascade reservoir reoperation

Decarbonization policy has promoted widespread deployment of clean energy and large-scale water-intensive coal-fired power phase-out (CPP), substantially reducing water demand and creating new opportunities to mitigate water conflicts in water-scarce basins. To manage this transition, the concept of equity inclination degree (EID) is proposed to mitigate allocation disparities, and a two-stage water resources optimization model incorporating EID is developed to assess the broad impact of CPP-induced water conservation on basin water management. The water allocation response coefficient (WARC) is proposed to uncover the adaptive response of water system to CPP, and the associated synergistic benefits under runoff uncertainty are evaluated using exceedance probability curve. The Yellow River Basin case study shows that CPP-induced water conservation is expected to raise the overall water satisfaction rate from 81.8 % in 2020 to 83.8 % by 2035. Additionally, hydropower generation will increase by an average of 0.18 TWh, and the downstream ecological water replenishment will witness an increase of up to 0.302 billion cubic meters in 2035. Runoff uncertainty affects the reservoir operation strategy under CPP, with water released by CPP prioritizing supply for provincial demands in low inflow conditions and shifting to hydropower generation and ecological replenishment in high inflow scenarios. Interprovincial water flow analysis indicates that the water conservation in upstream provinces triggers a favorable cascading effect, significantly enhancing hydropower efficiency. At the policy level, we recommend incorporating the EID into water allocation planning and establishing cross-provincial compensation mechanisms to promote the equitable distribution of cumulative benefits. Moreover, reservoir operation strategies should be adaptively adjusted considering supply-demand dynamics to maximize CPP-induced synergistic benefits.