Annual multi-objective optimization model and strategy for scheduling cascade reservoirs on the Yellow River mainstream

To enhance the water use efficiency in the Yellow River basin and alleviate the competition among the scheduling objectives of cascade reservoirs, we developed a comprehensive annual multi-objective optimization model based on basin systems science. This model integrated multiple objectives water and sediment management, ecological sustainability, and economic considerations. It was applied to the primary cascade reservoirs along the Yellow River mainstream: the Longyangxia, Liujiaxia, Haibowan, Wanjiazhai, Sanmenxia, and Xiaolangdi reservoirs. Using the Pareto solution set, we examined the optimization scope and potential adjustments under varying hydrologic frequencies, obtaining an optimized scheduling strategy informed by the “runoff conditions − trade-off relationships − optimization space”. The results indicated that as the runoff increased, both the optimization space and magnitude increased. A competitive relationship was observed between power generation and sediment discharge, as well as between ecological needs and sediment discharge, with competition intensifying as runoff increased. During dry years, power generation and ecological objectives were competitive, and this relationship gradually collaborated with increased runoff. A comparison between the segmented and established models demonstrated the superiority of the segmented approach. This study contributes to alleviating water use conflicts in the Yellow River basin, enhancing water utilization efficiency, and supporting effective management of the Yellow River.