In the last decade many research projects have been developed concerning the breaching of embankment dams. In particular in the framework of the IMPACT Project, results were provided for five large scale field tests and for 22 laboratory tests, so providing the basis for a better comprehension of the breach enlargement process, but also giving useful data for numerical modelling. This paper presents the results of the simulations of some of these tests, where the erosion is triggered by the overtopping of the dam. The simulations were carried out through a physically based model proposed by Macchione. The numerical results confirmed the soundness of the physical basis of the model.