Abstract:

[Objective] With increasing water resource development and growing ecological demands in the Hanjiang River Basin, conflicts between intra-basin water consumption and inter-basin water transfer, as well as between comprehensive water utilization and ecological water allocation, have become increasingly prominent. It is necessary to strengthen water allocation capacity through scientific methods, coupled with coordinated strategies for riverine-lacustrine habitat restoration and ecosystem health maintenance. [Methods] To address the coordinated requirements of water supply, power generation, and ecological benefits, a multi-objective optimized scheduling model for the Danjiangkou Reservoir was established, with the objectives of maximizing water transfer volume to the North, annual power generation, and ecological flow guarantee rate. The NSGA-III algorithm was innovatively improved by introducing a differential mutation operator and an adaptive crossover strategy, thereby enhancing the solution efficiency of the multi-objective optimization model. Additionally, a river hydrological health assessment method was incorporated to provide new insights for maintaining the ecological stability of the reservoir river section and the middle-lower reaches of the Hanjiang River. [Results] The optimization results showed that the ecologically optimized scheme significantly improved the ecological flow guarantee rate, with increases of 100%, 46.65%, and 88.89% in wet, normal, and dry years respectively. The optimization effects were significant, maximizing ecological benefits while strengthening water allocation. The river hydrological health assessment of the ecologically optimized scheme revealed that under low-inflow conditions, the optimized scheme effectively promoted overall river hydrological health. [Conclusion] The optimized scheme plays a positive role in ensuring the water transfer volume to the North, improving the ecological environment of the middle and lower reaches, and strengthening water resource allocation. Under reduced inflow conditions, compared to the conventional scheme, the optimized approach substantially improves comprehensive utilization efficiency and reduces water wastage. While pursuing ecological benefits, it alleviates the competition between ecological, water supply, and power generation demands. Furthermore, the river hydrological health assessment of the ecologically optimized scheme demonstrates that under low-inflow conditions, the optimized approach helps enhance overall river hydrological health, thereby promoting ecological stability in the downstream of the Danjiangkou Reservoir during dry periods. This study provides new insights for maintaining the ecological stability of the reservoir river section and the middle-lower reaches of the Hanjiang River.

Key words: Danjiangkou Reservoir, multi-objective optimal scheduling, NSGA-Ⅲ optimization algorithm, ecological flow guarantee rate, river hydrological health assessment