Evaluation of earth dam overtopping risk by system dynamics, Monte-Carlo simulation and Latin Hypercube Sampling methods (case study: Hajilarchay Dam, Iran)

Risk assessment of structures, especially dams, has recently been one of the main topics that are considered by researchers. Risk analysis make possible to estimate uncertainties coming up from randomness of parameters in the models which are applicable in designing process. In this paper, different uncertainties along with flood and wind with various return periods segregated and simultaneously were exploited to mitigate the overtopping risk of Hajilarchay earth dam. To assess the risk in the proposed model, we used Monte-Carlo simulation (MCS) and Latin hypercube sampling (LHS) method with different iterations through system dynamics approach. The results proved the effectiveness of system dynamics approach on overtopping risk assessment for earth dams which showed the influences of different parameters on overtopping risk besides flood and wind. Furthermore, the results showed that opening the bottom outlet of Hajilarchay Dam may reduce the average overtopping risk as much as 9.20 and 4.10 percent due to just flood and due to flood and wind, respectively. In addition results showed that the average overtopping risk estimated from MCS method due to just flood and due to flood and wind were about 4.30 and 3.50 percent, respectively, more than that the results obtained by the LHS method. Also the reliability index obtained by the MCS method was higher than LHS method and MCS method has faster calculation in compare to the LHS. Finally, we can conclude that system dynamics approach along with MCS is a very effective tool to estimate the overtopping risk of earth dams.