Risk and uncertainty analysis for earth dam overtopping- Case study: The Doroudzan dam, Iran

There is a growing tendency to assess the safety levels of existing dams based on risk and uncertainty analysis using mathematical and statistical methods. This research presents the process and application of risk and uncertainty analysis to dam overtopping and applies a probability-based methodology to evaluate the probability of earth dam overtopping. A flood frequency analysis of 33-year annual maximum discharge was carried out by applying General Extreme Values (GEV) distribution for the Doroudzan reservoir in the south of Iran. The procedure includes univariate flood and wind speed frequency analysis, reservoir routing, and integration of wind set-up and run-up to calculate the reservoir water elevation. The highest water levels in the reservoir were computed by using the reservoir routing technique and considering the quantile of flood peak discharge, initial depth of water in the reservoir, and spillway discharge coefficient as uncertain variables. Afterward, the probability of overtopping due to flood and combination of flood and wind speed for return periods of 50, 20, 10, 2, 100 years and 4 different water levels were evaluation by applying Monte Carlo simulation and Latin hypercube sampling.