Overtopping risk management by system dynamics and Monte-Carlo simulations, Hajilarchay Dam of Iran

Dams are effective in controlling the flood and reducing its damage. But, during the flood, the overtopping and the flow of water from the dam is always threatening it. Therefore, in order to maintain the dam safety against flood and also to maintain the efficiency of the dam, it should be balanced between the water level in reservoir of dam and its overtopping risk. Using the system dynamics, a set of complex, relevant, and effective overtopping factors could be simulated to examine the impact of different scenarios. The current research investigated the effect of different parameters on the overtopping risk on Hajilarchay dam (Northwestern Iran) using the system dynamics and Monte Carlo simulations, and estimated the human losses caused by the dam failure using of 441 and 118 persons for two cases of without warning and adequate warning, respectively. The overtopping risk of 〖2.27×10〗^(-6) was calculated in accordance with the USACE method. Given this risk value, a reliable level for reservoir water is set to 1040.70 meters above sea level, and the agriculture area at the downstream is set 1660 hectares for development. The results also show that the overtopping risk will increase by increasing the life of the dam, especially after 20 years, due to accumulation of sediment and settlement of the dam, and considering too much increase in overtopping risk caused by the change of dam’s spillway in order to save the cost of its construction, then adaptation strategies are provided including reservoir water level control.