Synergistic optimization of the Han-to-Wei project under dry conditions via the MOEA/D-PFE: a case study of the Huangjinxia reservoir

Interbasin water transfer (IBWT) projects are essential for regional water security, yet complex trade-offs exist among reservoir operation objectives under variable hydrological conditions. Taking the Huangjinxia Reservoir of the Han-to-Wei River Diversion Project as a case study, this paper investigates the synergistic operation dilemma of water supply and power generation under a 75% dry-year hydrological scenario. The Multi-objective Evolutionary Algorithm based on Decomposition with Pareto Front Estimation (MOEA/D-PFE) is employed to address solution clustering caused by strong nonlinear operational constraints by dynamically adjusting weight vectors according to the geometric characteristics of the Pareto front. The key findings are summarized as follows: (1) Pareto-front analysis reveals a clear trade-off between water diversion and hydropower generation under dry conditions; (2) Quantitative comparisons with NSGA-II and standard MOEA/D show that MOEA/D-PFE achieves better solution uniformity and reduces the SP by 57.2%. The improved solution coverage enables decision-makers to explore a wider range of feasible operational strategies under water-scarce conditions; (3) The optimized operation schemes demonstrate the practical rationality of raising reservoir water levels to compensate for generation head and prioritizing water supply during dry periods. This research provides practical reference value for the refined operation of IBWT projects under water shortage conditions.