Erosion Modeling over a Steep Slope: Application to a Dike Overtopping Test Case

The most violent floods are due to the failure of embankments, such as dams or levees. In case of dike overtopping, the erosion over the steep downstream slope is one of the main processes leading to the breaching. This study analyses the ability of numerical models to simulate this process. Various sediment transport formulations are presented and compared. A special attention is paid to the ways to account for the slope effects in these expressions. These sediment transport equations are included in two different one dimensional numerical models, based on the assumptions of a clear water layer and of a sediment-water mixture layer respectively. These two models are applied on a new dike overtopping experimental test-case, representing a small-scale sand dike with a sand layer downstream of the dike. The numerical results are compared to the experimental measurements, with a special attention paid on the sediment transport formulation, on the steep slope correction factor, and on the choice of the numerical model.