Summary: The two-dimensional laminar quasistationary interacting boundary layer flow with mass transport of a suspended sediment is solved over an erodable bump (or dune) in the case of a fluvial regime. It is assumed that, if the skin friction goes over a threshold value, the bump is eroded, and then the concentration of sediment in suspension is convected but falls at a constant settling velocity. This changes the shape of the dune, and examples of displacement toward final equilibrium states are presented.