F-N Curves for Public Safety Risks Associated with Dam Failures in the United States

With the advancing use of risk-informed decision-making in dam safety, there is interest in identifying tolerable public safety criteria or guidance for dam failures. Historical data has been used as a benchmark for establishing tolerable risk guidelines in use today. One metric for measuring public safety risks is the F-N curve, which shows the frequency of exceedance per year (F) of fatalities (N or more). In this paper, we present the development of an F-N relationship for dam failure-related fatalities based on an up-to-date database, statistical analysis, and evaluation of uncertainties. The result of the analysis is an estimate of the F-N curve that includes an estimate of the uncertainty (5-95% confidence intervals) in the results. The findings from this assessment provide a perspective on the scale of the threat dam failures have posed historically in the United States, a basis for comparison to other industries, and may be a useful baseline for future dam safety guidelines.