Limitations of Hydraulic Geometry Techniques in Stream Restoration Design

Hydraulic geometry techniques, which were developed in the 1950s, have undergone a renewed popularity in the last five years. It has been suggested by many that these relations can be used to check field data, to assess channel condition, and to design channel re-alignments for stream restoration projects. There has also been recent interest in developing new hydraulic geometry relations for local watersheds, both for design and for regulatory use in evaluating channel modifications. Although hydraulic geometry relations are useful, they can easily be mis-applied. A combination of hydraulic geometry theory and analytical techniques can result in a cost-effective design method which is adapted to site-specific conditions. The use of hydraulic geometry relations alone for final design of channel re-alignments has severe limitations.