| Abstract: | In order to gain a deeper understanding of the dynamics of erosion and sediment transport on hillslopes, it seems important to clarify the role of some basic mechanisms involved in these processes. While there is evidence that this cannot be done using the theoretical framework of river hydraulics, the use of numerical analysis could be of considerable help. The nature of the problem requires a technique capable of solving Navier–Stokes equations at low Reynolds number, with geometrically complex boundaries and solid particles moving inside the flow field. All these requirements make a novel method, known as lattice gas automaton LGA, a natural candidate for the study of the hydrodynamics of sheetflows. However, due to the recent introduction of this technique, there is a lack of a clear definition of its operational limits. Considering the case of a viscous sheetflow on an erodible rough boundary, we argue that by using LGA the stream Reynolds number can be increased only at the expense of a reduction of the boundary shearing stress. Accordingly, LGA cannot profitably be used to study the beginning of sediment motion and transport. On the other hand, a further evolution of LGA, known as the lattice Boltzmann method, seems highly promising for the numerical study of the erosion processes that eventually lead to drainage network evolution along hillslopes. © 1997 by John Wiley & Sons, Ltd. |
