Optimization of Gheshlaq Dam Water Allocation in Chance-Constrained Linear Programming Approach

Optimal operation of dam reservoirs is one of the important issues in the field of water resources management. In this study, optimal operation of dam has been investigated in a deterministic and probabilistic manner in order to supply maximum water demands of the dam downstream. The optimal allocation conditions of the system are examined by considering the probabilistic inflow and investigating the effect of cumulative distribution function on meeting the water demands. The chance constrained linear programming method has been used in the uncertainty approach for reservoir inflow. The study area is considered in Gheshlagh Dam located on Maryam-Negar River in Kermanshah province. Water supply optimization of water demands on downstream has been presented by using coding in LINGO software environment in two different modes. The results of optimization by deterministic approach show that the supply in the agricultural, domestic, and environmental water demands are 92%, 95% and 95%., respectively. In the probabilistic approach, considering the uncertainty in the inflow to the reservoir in two different ways, the results showed that not only is it not necessary to choose the best statistical distribution model of the inflow to the reservoir and the experimental distribution of Weibull is sufficient for this purpose, but also due to the reduction of the inflow volume to the reservoir, the optimal volume of the dam reservoir with a confidence level of 60% was estimated to be equal to 27.3 MCM. In this volume, the dam reservoir is fully able to supply the downstream demands of Gheshlagh Dam. Therefore, due to the uncertainty of the precipitation phenomenon, consequently the inflow to the dam reservoir and the obtained results, this approach is essential in the design and optimal use of dam reservoirs.