Sediment transport models to simulate erosion of overtopped earth-dikes

Abstract

An accurate simulation of the erosion of an earth-dike by overtopping is directly linked to the choice of the sediment transport model. The model should account for rather high sediment transport on the steep downstream slope. This study presents two different numerical approaches to simulate the overtopping of a river embankment. The first approach is based on the classical coupled Saint-Venant-Exner equations, as-suming one layer of pure water over a movable bed that can undergo erosion or deposition. Several empirical formulations are used to estimate the sediment transport capacity. The second approach assumes a fluid layer composed of a mixture of water and sediment, characterised by a depth-averaged density, for which the bed deformation rate is modelled as a function of both the erosion and deposition rates. These two models are compared with laboratory experiments on a one-dimensional dike failure due to overtopping, for which both the temporal water and sediment level evolutions were measured