Experimental study of rivers, including variability and response to imposed changes, is an important tool to understanding, managing, and restoring them. An important variable governing stream planform is the stability of a channel and its banks. NCED research is addressing some of the main questions related to modeling channel and bank stability at laboratory scales. Improved techniques for modeling stream dynamics will allow more widespread use of experimentation in stream restoration and experimental study of stream response to imposed anthropogenic and natural stresses.

River experiments have been hampered by our inability to reproduce the most common class of rivers on Earth--those with a single, well-defined channel that dynamically maintains its form. Therefore, a first set of experiments has focused on creating self-maintaining single-thread river channels. We have successfully shown that such channels can be experimentally developed using sand, vegetation, and variable water flow and that the channels reproduce many of the behaviors of natural single-thread rivers. A second set of experiments examines more closely the mechanisms by which a dynamic, single-thread channel is maintained and focuses on the relationship between bank erosion and bar growth rates and how these change in response to variability in water and sediment input rates.

Our experiments show the important role vegetation has in controlling channel morphology, supporting the common practice of using vegetation to stabilize streambanks. The effect of vegetation on the distribution of streambank shear stress and streambank stability are, nonetheless, poorly understood. A study of the effect of rigid cylinders on the near bank velocity distribution is intended to provide some insight into the mechanical effects of streambank stability resulting from the technique of planting willow posts along eroding banks.

One of the challenges of modeling bank stability is accounting for the component of bank strength provided by cohesive sediment. A project is underway to develop procedures for scaling streambank strength through careful measurements of cohesive streambank erosivity in prototype streams.