 This paper compares two different approaches for simulating free surface flows caused by a dam break. One approach uses the shallow water approximation, which does not account for the effects of gravity, while the other uses a more accurate three-dimensional model. The results show that the three-dimensional model better captures the full range of phenomena associated with a dam break, such as the formation of vortices and the development of a downstream wave train. This article was authored by C. Biscarini, S. D. Francesco and P. Mancilla.