This article aims at designing the mathematical model for Aras dam reservoir in time operation with missions of agriculture needs safeguarding, water electric energy production and torrent controls. Reservoir system relations determinate and these relations at framework of are determined and stochastic dynamic programming are calculated Executive results of this model are presentation of guides that shows the amount of reservoir output is relative to reservoir primary volume and input flow in current month and input flow in the month before in timely operation, the amount of input flow in current month not determinate, so it is necessity to one flow forecasting model.
In this manner with supposition of flow Markov process in the long of month is used passing for probability matrix between different states of flow. The results show that the stochastic model available the more amount water to securing of agriculture and water electric uses, therefore stochastic model is preferred in stead at deterministic mode
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