Optimal Reservoir Releases for Water Quality Control

A general mathematical model for determining optimal flow release sequences for water quality control from multiple reservoir systems is presented. The model defines an optimal release sequence which provides either the best quality of water or the least cost of reservoir storage for a given stream flow at a particular point in the system. Using the converging-branch multistage system of dynamic programming, the flow release problem is decomposed into a sequence of subproblems or stages. At each stage or decision point, which represents a confluence of two regulated streams, optimal release sequences are obtained by an efficient enumeration process. The flow release model incorporates formulations for BOD, DO, temperature, and physical relationships for stream flow, velocity, and depth. The facility of examining intermediate solutions at individual stages and the elimination of the need for continuous differential return functions are two of the principle features of the model.