Multiobjective Optimization in the Water Resources Problems of Kakogawa River Basin

Abstract

This paper deals with the water resources problems in the Kakogawa River basin from a view point of multiobjective optimization. The Kakogawa River is one of the greatest rivers in Hyogo Prefecture and its total area of the basin is nearly 1727 km2. This basin include Kakogawa and Takasago Cities where growing industrial activities are requiring extended developments of water resources on one hand and polluted stream waters are becoming a serious matter on the other hand.The model constructed is formulated as a multiobjective mathematical programming problem. The objectives of the decision maker are assumed to be 1) minimize total cost associated with the construction and operation of the facilities, 2) minimize the pollution in the basin, 3) maximize the supply water for the basin, and technical and physical constraints are quantity-balance conditions of both stream flow and water supplies as well as the BOD load balance conditions.The surrogate worth trade-off method proposed by Y.Y. Haimes is used to resolve the conflicts between the objectives. Although the objective functions are not necessarily convex, the optimal solution obtained is very satisfactory.