Determination of the Height and Overtopping failure of Reservoir Dams by Using Reliability Analysis (Case Study: Namrood Dam)

Generally, the design of dams and other hydraulic structures is carried out based on deterministic approaches. However, there are many uncertainties in the estimation of different effective parameters in hydraulic structures design. The inherent uncertainties in these parameters necessitate reliability analysis to ensure the structure stability. In this study, after investigating various uncertainties in design, the height and overtopping failure of Namrood dam as a case study was calculated based on reliability analysis. For this purpose, the Monte Carlo Simulation Technique that is a well-known method for reliability analysis, was used. Results showed that to get 100% safety from design flood, the height of Namrood dam should be considered as 78.7 m. However, in this case the probability of overtopping failure due to control flood was 64%. Moreover, similar analysis was carried out to investigate the effect of spillway type on overtopping probability of failure. Results showed that by increasing the spillway crest length, the probability of failure in the case of Morning glory spillway increased more rapidly than ogee spillway.