A quantitative technology for supporting multi-objective decision making in hydropower operation

There is a conflict between the hydropower benefit of hydraulic engineering and other functions such as ecological protection, water supply, flood control, etc. Deciding on an appropriate scheme to balance the interests among multiple objectives is a crucial issue in hydropower operation management. The Pareto set is the carrier and embodiment of a multi-objective mutual feedback relationship. It has a constant increasing or decreasing tendency, and most distribute unevenly, meaning different change rates and sensitivities are embedded. Based on this understanding, a new idea of "profit/loss ratio" is obtained, which constructed the average change rate of each neighbouring non-inferior solution on the Pareto frontier. Processed dimensionless, a new non-dominated subset of Pareto non-inferior solutions is filtered out according to the dominance relationship to limit scheme selection scope. On this basis, a method for calculating the "bias degree" of each Pareto non-inferior solution relative to different objective functions is proposed, which leads to the quantitative evaluation of Pareto solutions and provides quantitative support for decision-makers select operation schemes according to their preferences. Taking the cascade reservoirs in the lower reaches of the Jinsha River Basin in China as a case, the trade-off between the two objectives of hydropower generation and ecological protection is investigated, and the feasibility and effectiveness of the methodology are verified.