洪泽湖多目标水量调度决策模型及其应用

Multi-objective operation and decision-making model of Hongze Lake and its application

针对洪泽湖水量利用与生态水位维持这一矛盾开展多目标水量调度决策方法研究,构建贴近适宜生态水位(生态效益)、缺水率最小、引水量最小、入湖水量改变度最小等目标的多目标调度模型,考虑生态效益目标与水资源利用目标的不可共度性及决策者偏好模糊性特征,采用多目标模糊决策法从非劣解集中筛选最适宜调度方案。结果表明:多目标模型解集反映生态效益和经济社会效益的置换关系,贴近适宜生态水位的调控方式在一定程度上降低洪泽湖调蓄能力,与水资源利用形成矛盾关系;模糊决策法筛选的均衡调度策略可以有效反映决策者的偏好情况,并提供适用于不同情景的优化调度方式;生态目标优先方案通过减少供水、增加引水量、调节入湖水量等方式有效补充生态用水,可将生态水位偏离差降低至0.30 m,可为生态优先原则下的适宜调度策略制定提供参考。

Lakes played critical roles in maintaining sustainable natural ecosystem function and providing operational services such as flood control,water supply,and irrigation.In many countries and regions,water resource and water shortage problems were intensified owing to increased demand associated with population growth and socioeconomic development.Owing to water resource shortage problems in lake systems,overuse of water resources would lead to the minimum reserved water volume required for ecological purposes being diverted for human consumption,resulting in severe ecological degradation.To restore the ecological condition of lakes,it was critical to resolving the conflict between consumptive water use and ecological water use through multiobjective reservoir operation and informed decision-making.With explicit identification of the ecological and other water demands,together with consideration of streamflow conditions,this can be formulated as a multi-objective optimization reservoir operation and decision-making modeling problem.The operation of reservoirs aimed to maintain the water level and volume process of the upstream and downstream to meet the ecological guarantee demand,of which the difficulty would lie in how to coordinate the contradictory relationship among consumptive and ecological water use as well as water supply from multiple sources.For the decision-making problem,the ecological benefits,which could hardly be measured accurately,made it necessary to consider fuzziness in the process of decision-making.To resolve the above problems,a multi-objective reservoir operation model was established based on suitable ecological water levels,aiming for the ecological problems of Hongze Lake in Huai River Basin,China.From the perspective of opening sources and reducing consumption,objective functions for minimizing ecological water level deviation,water shortage percentage,diverted water,and reservoir inflow deviation was addressed to evaluate the ecological benefits and costs of reservoir operation.To select the optimal compromise from the Pareto set derived from the multi-objective operation model,the fuzzy optimum selecting model was introduced to select optimal operation strategies,reflecting the equilibrium between ecological security and water supply comprehensively.Finally,Hongze Lake was taken as a study case to conduct multi-objective operation modeling and fuzzy decisionmaking.The main contributions of this study comprise the following:(1)Tracking the suitable ecological water level would sufficiently lower the regulation capability of Hongze Lake to a certain extent,which either affected water delivery or necessitates water diversion and supplemented inflow from releases by river engineering facilities,and the corresponding non-inferior alternatives reflected tradeoffs of ecological benefits and regulation costs.(2)The fuzzy optimum selecting model can screen the alternative set under perturbation of fuzzy ecological information,and select appropriate operation strategies according to various decision-maker's preferences.(3)Compared with the alternative with minimum consumptive water shortage,the ecological priority alternative can effectively satisfy ecological demands by reducing water supply,increasing diverted water,and strengthening inflow regulation,which resulted in a low ecological water level deviation of 0.30 m,along with the increasing water shortage percentage,diverted water,and reservoir inflow deviation objectives up to 18.29%,1.070 billion m3,and 14.71%,respectively.By analyzing the water level process of Hongze Lake under different operation strategies,the ecological priority alternative showed relatively high diverted water in January,February,April,and May making the water storage of Hongze Lake more suitable to meet the ecological needs of animals and plants.The findings provided an effective framework to quantify and coordinate the conflicts between ecological benefits and economic costs,providing theoretical support and practical application value for solving the problems of multi-objective operation of reservoirs.