SOME REMARKS ON A MORPHODYNAMICAL MODEL FOR GRAVEL BED STREAMS

摘要

The analysis of morphological river processes is usually performed using a sediment transport uniform flow model, even in unsteady flow conditions, assuming then that instantaneous equilibrium is attained in bedload transport. Many researchers have proposed non-uniform models aiming to remove the local equilibrium hypothesis. In the present note, the study of the characteristic curves associated to non-equilibrium models is carried out. It is shown that, as in the classical St. Venant equations, non-equilibrium models allow the occurence of a vanishing charachteristic slope, or celerity so defining a critical state. The appropriate boundary conditions are also discussed.