Optimal Hedging Rules for Two-Objective Reservoir Operation: Balancing Water Supply and Environmental Flow

Analytical optimal hedging rules are derived for two-objective reservoir operation based on the characteristics of economic and multilevel environmental water demands. This approach is employed to balance current and future economic and environmental water demands using a two-period model. According to the marginal values of utilities, the derived three-step hedging rule curves (THRCs) consist of three steps and six stages. The Huaihe River basin of China is taken as an example to regress the THRCs from a two-objective optimization model. Results show that the derived THRCs can be regressed from the optimal release decision, thereby confirming the derivations and theoretical analysis. The shapes of the THRCs are sensitive to the weight parameters of the objectives and capture the core concern of multiobjective reservoir operation. The THRCs tend to widen and flatten the stages with increasing storage capacity, which implies more water storage and more consideration for future demands. (C) 2016 American Society of Civil Engineers.