Effect of the Operation Policy, Reliability Level and Allowed Deficit Threshold for Water Supply in the Optimum Reservoir Capacity

The optimum capacity of a reservoir is affected by two important assumptions considered in the design phase. The first one is the selected operation policy which means releasing flow at the operation time. The common reservoir operation policies in researches, mainly include the Standard Operation Policy, S-Type, SQ-Type and the techniques based on them such as GSQ-Type, GSQD-Type. The second effective parameters are assumed reliability levels and the allowed deficit threshold for water supply. In this study, the simultaneous effect of the selected operation policy, the reliability range, and deficit threshold on the optimum reservoir capacity of Marbareh in Lorestan province was investigated. For this purpose, determination of the optimum reservoir capacity in 4 operation modes which was predetermined as operation without any preset policy (Free Policy), SOP and S-Type and SQ-Type linear operation strategies considering concurrent reliability levels and deficit thresholds was performed. The results show that the optimum reservoir capacity was severely influenced by reliability levels, deficit thresholds, and selected operation policy. So that, in this study the reliability change from 50% to 100% changes the minimum reservoir capacity for different modes of operation policies and the accepted deficit thresholds from 5.2 MCM to 248.3 MCM. The effect of the uncertainty of the stochastic parameter of the inflow into the reservoir is considered by implicit method (using statistical series).