基于NSGA-Ⅱ算法的山区性中小流域水库群多目标生态调度研究

Research on the Multi-objective Ecological Operation of Reservoirs in Mountainous Medium-sized and Small Basins Based on NSGA-Ⅱ

水库群的建成和投运改变河流天然水文情势,对河流生态健康造成了不利影响。以往水库群生态调度研究多针对大流域平原地区,而对山区性中小流域的研究较为少见。为探究山区性中小流域水库群生态流量保障与水资源利用之间的相关关系,以马金溪流域建成的2座中型水库和1座大型水库为研究对象,以下游文图水文站调度后流量与天然径流偏差最小(AAPFD)、水电站总发电量最大和供水缺水量最少为优化目标,构建马金溪流域水库群多目标生态调度模型,采用非支配遗传算法(NSGA-Ⅱ)进行求解,研究P=50%、75%以及95%等不同频率来水条件下生态、发电和供水目标间的关系。研究结果表明:①随着马金溪流域来水增加,下游文图水文站AAPFD减小,水电站群发电量增加,流域供水缺水量减少,生态、发电及供水目标会随之改善;②在不同频率来水条件下,生态、发电和供水目标间存在竞争关系,其中,发电和生态目标间的竞争关系较强,与供水目标的竞争关系较弱;③分别选择生态、发电和供水目标最优的典型非劣解集作为方案1~3,其中,方案1和2在生态、发电和供水目标计算值差异性较大,而方案3与方案1、2相比是一种偏向折中的方案。研究结果可为马金溪流域水库群生态调度决策提供参考依据。

The construction and operation of reservoirs have changed the riverine hydrological regimes,causing adverse effect on riverine ecological health.Previous studies focus on ecological operation of reservoirs in large-basin plains,while few researches are about mountainous medium-small basins.To explore the relationships between ecological flow and water resources utilization of reservoirs in mountainous medium-small basins,this paper selects the two medium and a large reservoirs in the Majinxi Basin as a case study.A multi-objective ecological operation of reservoirs model is established to minimize amended annual proportional flow deviation(AAPFD)of the Wentu Station and total water deficit of the water region while maximizing the hydropower generation.The non-dominated sorting genetic algorithm(NSGA-Ⅱ)is applied to solve this model to research the relationship among the objectives of ecology,hydro-electricity and water supply under conditions of different inflow frequencies such as P=50%,75%and 95%.The results show:①with the increase in the inflow of the Majinxi Basin,the AAPFD of the Wentu Hydrological Station decreases,meanwhile the hydropower generation of reservoirs increases and the total water deficit of the water region declines,which improves the objectives of ecology,hydroelectric and water supply.②There is a competitive relationship among the objectives of ecology,power generation and water supply and the ecology objective has a stronger competitive relationship with the power generation objective than the water supply objective;③the typical non-inferior solutions with the optimal objectives of ecology,hydroelectricity and water supply are selected as schemes 1~3,respectively,and there is large variability in schemes 1 and 2 of multiobjectives while the scheme 3 is similar to a compromise scheme compared with the schemes 1 and 2.The research results can provide a reference for the ecological operation decision-making of reservoirs in the Majinxi Basin.