BI-OBJECTIVE DYNAMIC-PROGRAMMING FOR TRADING OFF HYDROPOWER AND IRRIGATION

Reservoir management is examined from the bicriterion viewpoints of hy dropower generation and irrigation. Specifically, a decision support s ystem is developed which includes constructing the set of non-inferior solutions, using the constraint, penalty and weighting methods. The r eservoir operation model, as well as the optimization and simulation s oftware, were initially provided by the R & D Division of the French E lectrical Utility (Electricite de France); the method is based on a St ochastic Dynamic Programming-SDP-model with daily time steps, using 50 annual values of daily historical inflows and marginal electricity pr oduction costs. The water requirement for irrigation is taken either a s preset using a demand curve, or as a soil reservoir model based on S DP and running simultaneously with the reservoir model. The model yiel ds trade-off curves of electrical production losses versus, respective ly, irrigated surface area, crop yield, and agricultural benefits. A n umerical application illustrates the methodology in the French case of the Bort reservoir, in the Dordogne valley. The model reveals that re leasing water fur irrigation could present economic advantages within certain constraints on maximum irrigated surface area and minimum wate r price. Consequently, the current economic justification of single pu rpose reservoir management for hydropower ought to be changed. Negotia tion should be initiated for the purpose of selecting one of the non-d ominated reservoir management policies, hereby minimizing the distance of the ''most preferred'' solution point from the ideal one or by usi ng the Nash cooperative game solution. Multicriterion decision-making seems to be a promising operational management tool for hydrosystems. (C) Elsevier Science Inc., 1997.