Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines
Log revetments with geotextile rolls in Colorado sustained velocities up to 10 fps, but
undermining the lower logs occurred in the lower part of the treated reach. A general rule
of thumb is that for velocities exceeding 8 fps, some combination of inert material be used
with plants that are well secured and have adequate toe and flank protection. The inert
material may be deflection structures made from root wads or rock hard points or dikes, etc.,
or the inert material may be wire and stakes that hold down plant material long enough for
that material to take hold. Even then, those materials, both inert and living plants, must have
enough toe and flank protection to allow sustainment through flood events. This sustainment
is especially critical during the early phases of the project.
Early monitoring and aftercare of a bioengineering project is essential. Each project
should have incorporated into it from the beginning enough time and funds to provide some
remedial work within the first year or so after treatment installation. It would be better to
provide this contingency for up to and immediately after the first one or two flood events.
Once weak spots in treatments are repaired, the bioengineered system continues to gain
strength over time.