We describe additions made to a multi-size sediment routing model
enabling it to simulate width adjustment simultaneously alongside bed
aggradation/incision and fining/coarsening. The model is intended for
use in single thread gravel-bed rivers over annual to decadal timescales
and for reach lengths of 1-10 km. It uses a split-channel approach with
separate calculations of flow and sediment transport in the left and
right sides of the channel. Bank erosion is treated as a function of
excess shear stress with bank accretion occurring when shear stress
falls below a second, low, threshold. A curvature function redistributes
shear stress to either side of the channel. We illustrate the model
through applications to a 5.6-km reach of the upper River Wharfe in
northern England. The sediment routing component with default parameter
values gives excellent agreement with field data on downstream fining
and down-reach reduction in bedload flux, and the width-adjustment
components with approximate calibration to match maximum observed rates
of bank shifting give plausible patterns of local change. The approach
may be useful for exploring interactions between sediment delivery,
river management and channel change in upland settings. Copyright (C)
2011 John Wiley & Sons, Ltd.