Use of a Multi-Objective Correlation Index to Analyze the Power Generation,Water Supply and Ecological Flow Mutual Feedback Relationship of a Reservoir

Hitherto, there has been insufficient work to quantify the degree of mutual feedback among the different objectives of multi-objective reservoir operation. The purpose of this study is to use a Multi-objective Correlation Index (MCI) to quantitatively analyze the complicated relationship of a multi-objective reservoir operation under changing inflow and water demands. First, an improved maximum probability density function method has been used to generate the adaptive ecological flow thresholds in long-term, wet-year, normal-year and dry-year inflow scenarios. Based on these ecological flow thresholds, a multi-objective reservoir optimal operation including the three objectives of power generation, water supply and ecology is constructed to research the tradeoff relationship among the objectives. Moreover, using the optimal solution set as determined by the Progressive Optimality Algorithm-Particle Swarm Optimization (POA-PSO) algorithm, the MCI is used to quantify the degree of the tradeoffs and their trends in responding to the changing conditions. The results show that the synergistic degree between the water supply and ecological objective decreases when the climatic condition changes from wet years to dry years, while the conflicting degree of power generation with respect to water supply or ecological objectives increases. Furthermore, the major degree of tradeoffs changes from the power generation-ecological flow objective pair to the power generation-water supply objective pair. In general, the MCI is able to quantify the extent and characteristics of the tradeoffs between different objectives. Hence, this index is useful for managers to make more informed and transparent decisions.