| This study explored uncertainties involved in a dam safety risk assessment. The impacts of uncertain inputs to a dam risk analysis model (i.e., loading conditions, system response probabilities and consequences) were quantified by the uncertainty runs of the model and examined using uncertainty analysis. Probability density functions were assigned to the uncertain inputs, and random values were generated from these functions using the Latin Hypercube Sampling technique. Simple probability density functions were used, and their distributional parameters were selected using the available data and engineering judgment. Probability density functions for the depth and extent of downstream flooding with and without dam failure, which are necessary for estimating the downstream consequences, were obtained from uncertainty runs of a dam breach flood routing model. Downstream flood profiles and flooded areas estimated from dam breach flood routing were found to be very sensitive to the dam breach size, breach formation time, and Manning's roughness coefficients. The influence of these uncertain inputs was therefore included in the process of the consequence assessments.; This study developed and tested a systematic framework for quantifying the effects of uncertainties in flood routing on a consequence assessment for dam safety risk assessment. It included estimates of confidence levels in risk evaluations for dam safety. It has shown that uncertainty analysis associated with risk assessment can provide the decision-maker, such as the dam owner, regulator, and engineer, with additional and valuable information for selecting a risk reduction measure. Insights into the effects of uncertainties can be expected to better position the decision-makers to be able to choose an optimal plan to manage dam safety risks and to justify their decision. |
