Modeling the Hydraulics and Erosion Process in Breach Formation Due to Overtopping

Abstract

Many cases of breach initiation in a dike or embankment dam due to overtopping have been recorded internationally, very frequently resulting in complete failure of the structure. This in turn has led to extensive material and human loss downstream. In fact, overtopping is cited as the more common reason for failure rather than ‘piping’ in rockfill or earth dams. Overtopping generally occurs due to large inflows into the reservoir that are either caused by excessive rainfall or by the failure of an upstream dam. The resulting volume of water entering the reservoir can well be beyond spillway evacuation capacity. The overtopping failure of two embankments in 1996 on the Chicoutimi river due to excessive rainfall is a recent example in Canada.