Using Erosion Rate To Refine Earth Dam Breach Parameters

This article was developed from a paper that was presented at Dam Safety 2008 and reflects more than 50 years of combined experience by the authors in estimating breach parameters for the computer simulation of earth dam failures. Simulating the failure of earth dams is a key analysis step in the development of dam-failure flood inundation maps for dam emergency action plans, evaluating dam hazard classifications, and performing risk assessments for dams. One of the most important results from these evaluations is an estimate of the peak breach discharge that can be expected if a dam were to fail during either sunny-day or extreme flood events. The peak flow from a dam breach is very sensitive to breach development time, final breach width, and breach initiation elevation. The appropriate selection of these and other breach parameters requires considerable engineering judgment. This article describes a five-step process that relies on the erosion rate to minimize the subjective judgment that can occur when selecting breach parameters. This article also presents several case studies to illustrate how this process can be used to develop realistic dam breach parameters for earth dams. 9 pp., 12 references.