New paper: Evolution of channel belts

About: Turowski et al., (2025), Earth Surface Dynamics (link)

Chapter four of our work on how channel belts and valleys set their widths is out now. We use a random walk model to make predictions on how channel belts widen. The model is consistent with observations from both experiments and the field, and it is governed by three timescales.

On short timescales, the river moves in just one direction. Then, the channel belt widens linearly at a rate that depends on the rivers “lateral transport capacity”. We introduced the concept of this lateral transport capacity here. On medium timescales, the river moves back and forth across the channel belt. Then, the evolution of channel-belt width can be modelled with an exponential approach to an asymptote. On long timescales the river erodes the margins of the active channel belt only occasionally. The channel belt widens as the squareroot of time.

Evolution of channel-belt width over time. Colored lines are data from a random walk model. Dotted, dash-dotted and dashed lines are predictions from analytical solutions for the linear-, exponential-, and squareroot-widening phases.

The model makes predictions on the age of floodplain surfaces, and it fits rare data on floodplain ages well.

The distribution of floodplain ages in the field scale with a power-law exponent of ~3/2 as predicted by the random walk model.

Leave a Reply

Your email address will not be published. Required fields are marked *