2023 – A Method for Assessing the Likelihood of Overtopping Failure for Earthfill Embankment Dams

Nicholas Ostrovsky, Chi-Fai Wan

Overtopping failure of earthfill embankments is a principal cause of large dam failures around the world and this is typically the result of insufficient spillway capacity. With a climate that is warming and making storms more intense and more frequent, existing dams in Australia are at a greater risk due to spillway inadequacy and overtopping risk in the future. Risk assessments are tools used to assess the risk of overtopping failure. However, there are few universally accepted methods available to estimate the likelihood of overtopping failure for earthfill embankments. This paper presents an analytical method to estimate the likelihood of embankment overtopping failure based on the following key factors including overtopping depth, flood discharge over dam crest, velocities of flow over the dam crest and downstream slope of the embankment, duration of overtopping, and erosion resistance of the materials on the dam crest and downstream slope.

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