Numerical Modeling of Embankment Failure due to Overtopping

Embankment failures during extreme storms can result in catastrophic damages that include losses to property and life. The most common cause of failure is water overtopping the embankment. The embankment failure process is complex because of rapid changes in the flow and breach geometry. Accurate predictions of breach evolution help in better emergency preparedness plans. In this work, a two-dimensional numerical model is developed and applied to a real-life embankment failure by overtopping during the historic October 2015 flood in South Carolina. The model governing equations are the depth-averaged shallow water equations for flow and the sediment mass conservation equation. A unique feature of the model is its ability to simulate discrete slumping of breach sidewalls during the failure, not available in other available models. The model is designed to capture the failure stages according to different breach characteristics (i.e., breach dimensions and the breach hydrograph) during the unsteady phase of the failure. The comparison between of model results and field measurements shows a satisfactory agreement between the observed and measured final breach top width as well the maximum eroded breach depth.