Reclamation’s Empirical Method for Estimating Life Loss Due to Dam Failure

Abstract

The Bureau of Reclamation (Reclamation) estimates life loss resulting from dam failure in support of dam safety risk analysis. To estimate life loss, Reclamation relies primarily on an empirical methodology which is tied to the interpretation of case histories of dam failures and other types of flood disaster events. The method is known as Reclamation’s Consequences Estimation Methodology, or RCEM. RCEM is a revision to an empirical method used by Reclamation since 1999, for which the case history database has been substantially expanded. Case histories, which come from dam failures, flash flood and coastal flooding events, are the basis for data points used in the estimation of fatality rates. Reclamation’s RCEM methodology employs a graphical approach for the selection of fatality rates based on ranges of DV (depth multiplied by velocity) and warning time. DV is used to quantify the intensity of flooding and can be related to lethality. The RCEM methodology is in many ways similar to Reclamation’s previous method, DSO-99-06. However, the new method requires greater application of judgment when selecting fatality rates. The paper will provide an overview of the new method, with emphasis on the case histories, and discussion of the importance of a team approach to life loss estimation.