Sediment transport by a fluid over a sediment layer can be modeled by a coupled system with a hydrodynamical component, described by a shallow water system, and a morphodynamical component, given by a solid transport flux. Meyer-Peter and Müller developed one of the most known formulae for solid transport discharge, but it has the inconvenient of not including pressure forces. This makes numerical simulations not accurate in zones where gravity effects are relevant, e.g., advancing front of the sand layer. Fowler et al. proposed a generalization that takes into account gravity effects as well as the length of the sediment layer which agrees better to the physics of the problem. We propose to solve this system by using a path-conservative scheme for the hydrodynamical part and a duality method based on Bermudez-Moreno algorithm for the morphodynamical component.