Stable alluvial channel geometry

This study numerically computes stable alluvial channel geometry by finding a bank profile for known water and sediment discharges and uniform sediment size. The sediment concentration along curving banks is found by solving numerically the steady state diffusion of sediments in the bank regions using the Finite Element approach. Analysis shows that a simple power law can represent the stable profile of the bank region. For each value of dimensionless diffusion coefficient E pertaining to stable bank geometry, the analysis predicts a unique pair of bank region aspect ratio and power law profile. This aspect ratio and the power law profile of the bank region along with flow resistance and sediment transport relations are used to solve the geometry of alluvial channels. This model has been tested against 66 sets of experimental data and 506 sets of field data and results demonstrate that the predicted alluvial channel geometry values fall within the limits of +/-50% of observation.