Probabilistic Assessment of Overtopping Reliability of a Dam

Probabilistic methods, which consider resistance and load parameters as random variables, are more realistic than conventional deterministic methods for determining the safety level of a dam. This study is based on a probabilistic assessment of overtopping reliability of a flood detention dam. In the analysis, the inflow hydrograph parameters and the initial reservoir level prior to the allocation of the flood in the reservoir are accepted as random variables. A bivariate flood frequency analysis is performed in which the annual maximum peak discharges and the surface runoff volumes of the floods are handled as the random variables, using bivariate gamma probability density function. This operation yielded a number of flood hydrographs having different peak discharges and runoff volumes under a particular return period. Using this information, family of return period curves relating the runoff volume to peak discharge are generated at the dam site. Maximum reservoir elevation is determined by performing reservoir routing based on Monte Carlo simulation. This calculation is repeated for various combinations of possible flood hydrographs under a constant return period to observe the variation of overtopping reliability. It is, therefore, intended to find the most critical case that is likely to occur at the dam site. The findings of the present analysis may be used in decisionmaking for the crest elevation of the dam, which is safe against overtopping.


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Citation Formats
A. M. Yanmaz, “Probabilistic Assessment of Overtopping Reliability of a Dam,” presented at the International Conference on Water Observation and Information System for Decision Support (23 - 26 Mayıs 2006), Ohrid, Macedonia, 2006, Accessed: 00, 2021. [Online]. Available: