Numerical Modeling of Embankment Failure due to Overtopping

Embankment failures can result in considerable property damage and fatalities. The most common cause of embankment failure is overtopping due to high water level in the river. The embankment failure process is complex because of rapid changes in flow and breach geometry. Accurate predictions of breach evolution help improving emergency preparedness and evacuation plans. In this work, a two-dimensional numerical model is developed and applied to simulate a real-life dam failure by overtopping during the historic October 2015 flood in South Carolina. The depth-averaged fluid mass and momentum conservation equations, known as shallow water equations, along with the sediment mass conservation equation are solved numerically. A unique feature of the model is the ability to simulate discrete slumping of breach sidewalls. The model captures the failure stages and estimates breach characteristics including breach dimensions and the breach hydrograph during the unsteady and steady phases of the failure. The comparison between model results and field observation shows a satisfactory agreement between the observed and simulated final breach-top width as well as the maximum eroded breach depth.