Uncertainty in Dam Failure Consequence Estimates

¹ Director, National Performance of Dams Program, Department of Civil and Environmental Engineering, Stanford University, USA
² Principal, Schnabel Engineering, West Chester, PA, USA

^a Corresponding author: mccann@jbaslc.best.vwh.net

Abstract

When performing risk analyses for flood studies or dam safety projects, it is common to use best estimates for flooding probability, the peak flood levels, and for damage from the flooding to estimate the “expected” value of economic consequences or fatalities. Typical practice does not consider the uncertainties (aleatory and epistemic) in various elements of the risk analysis, In risk analysis for dams, the failure to address uncertainties in the elements of the risk analysis can have important implications to; 1) understanding the distribution of consequences that can result from a dam breach, 2) level of confidence in the risk results, 3) potential area of inundation, the residences, infrastructure, and the population-at-risk, and 4) deriving a Bayesian estimate of the expected-value of losses from a dam breach. This paper includes an approach for estimating uncertainties and the effect of these uncertainties in the dam breach and inundation analysis and in the flood damage relationships on the estimate of flood damages. The aleatory and epistemic uncertainties in the frequency of dam failure, the dam breach and inundation analysis and in the flood damage assessment are explicitly propagated through the estimates of the frequency distribution on downstream consequences.