Modeling River Planforms and Floodplains
In recent years considerable progress has been made in creating simulation models of fluvial landforms. These will be reviewed, including in particular:
- braided stream patterns
- meandering channels and floodplains
- deltas and alluvial fans
Notes:
Predictive modeling of the development of stream patterns and their associated landforms has been challenging. Until about the 1980’s the literature was replete with papers postulating why stream channels -- including the suggestion that meandering was initiated by Coriolis forces. We now understand that meandering is a nearly inevitable consequence of the development of secondary flows in any channel bend. The theoretical breakthrough was the linearized model of flow in channels by Ikeda, Parker, and Sawaii (Ikeda, S., Parker, G., and Swaii, K., 1981, Bend theory of river meanders, 1, linear development, J. Fluid Mech., 112, 363-377).
The situation with regard to braided channels is still pretty much like that of meandering 20 years ago. There are many observations and qualitative explanations and classifications of braided channel development, but no compelling theory capturing the essence of braiding. This is at least in part because of the complexity of flow and sediment transport in multiple channels.
This presentation reviews progress in modeling channel evolution and floodplain morphology, based upon the following review paper:
Howard, A.D., 1996, Modelling channel evolution and floodplain morphology, in Floodplain Processes, (M.G. Anderson, D.E. Walling, and P.D. Bates, eds.), John Wiley & Sons, p. 15-56.
Illustrations are from this paper unless otherwise noted.