Prediction of Embankment Dam Breaching for Hazard Assessment

by R. L. Dewey, U.S. Bureau of Reclamation, Boise, United States,
D. R. Gillette, U.S. Bureau of Reclamation, Boise, United States,

Document Type: Proceeding Paper

Part of: Geotechnical Practice in Dam Rehabilitation


Downstream hazard assessments for dams require prediction of 1) whether a breach could form, and 2) the hydraulic characteristics of the breach for use in calculations of discharge and downstream water levels. The paper presents a practical approach to breach prediction for use in safety evaluations of small to medium-sized embankment dams subject to overtopping. If flood routing indicates that the design flood would overtop the dam, the expectation of erosion-induced breaching is established by calculations to determine whether the tractive force created by the flow is sufficient to dislodge particles from granular downstream slope surfaces. Once it has been established that the dam would be breached by overtopping, or any other cause, the dimensions and rate of formation of the breach are estimated by comparison with a data base of 60 dam failure case histories.

Subject Headings: Embankment dams | Dam failures | Disasters and hazards | Wave overtopping | Flood routing | Piping erosion | Failure analysis | Water discharge

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