Fuzzy Dynamic Programming Model for Operation of Multipurpose Reservoir

Multipurpose reservoir operation involves various interactions and trade-offs between purposes, which are sometimes complementary but often competitive or conflicting. Reservoir operation may be based on the conflicting objectives of maximizing the amount of water available for conservation purposes and maximizing the amount of empty space for storing future flood waters to reduce the downstream damages. A major complicating factor in water resources system management is handling uncertainty. Reservoir management is one of the such complex problems which involves the uncertainty. Various models have been reported in literature for developing optimal operation policy for a reservoir. Most of these models consider the uncertainty caused due to variability of inflows. However uncertainty caused because of imprecise objectives and goals is also an factor in developing operation policy of a reservoir. In recent years fuzzy optimization models have generated considerable interest. In the present study a Fuzzy Dynamic Programming (FDP) model is developed for optimal operation of a multipurpose reservoir and is applied to Hirakud Reservoir for deriving the ten daily operating policy for the reservoir. Hirakud project is a multipurpose project on river Mahanadi in the State of Orissa in India. The main objectives of the Hirakud project are irrigation, hydropower generation and flood control. The objectives are treated as fuzzy, and membership functions are developed for the linguistic variables describing the objectives. The objective function of the FDP model is to maximize the minimum expected satisfaction level of the fuzzy objectives. The FDP model is used to develop the optimal operating policy of the reservoir. The reservoir is simulated using the operating policy derived from FDP model and the performance of the reservoir is evaluated. The study demonstrates the applicability of fuzzy optimization for reservoir operation.