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Critical evaluation of how the Rosgen classification and associated "natural channel design" methods fail to integrate and quantify fluvial processes and channel response

Publication ,  Journal Article
Simon, A; Doyle, M; Kondolf, M; Shields, FD; Rhoads, B; McPhillips, M
Published in: Journal of the American Water Resources Association
October 1, 2007

Over the past 10 years the Rosgen classification system and its associated methods of "natural channel design" have become synonymous to some with the term "stream restoration" and the science of fluvial geomorphology. Since the mid 1990s, this classification approach has become widely adopted by governmental agencies, particularly those funding restoration projects. The purposes of this article are to present a critical review, highlight inconsistencies and identify technical problems of Rosgen's "natural channel design" approach to stream restoration. This paper's primary thesis is that alluvial streams are open systems that adjust to altered inputs of energy and materials, and that a form-based system largely ignores this critical component. Problems with the use of the classification are encountered with identifying bankfull dimensions, particularly in incising channels and with the mixing of bed and bank sediment into a single population. Its use for engineering design and restoration may be flawed by ignoring some processes governed by force and resistance, and the imbalance between sediment supply and transporting power in unstable systems. An example of how C5 channels composed of different bank sediments adjust differently and to different equilibrium morphologies in response to an identical disturbance is shown. This contradicts the fundamental underpinning of "natural channel design" and the "reference-reach approach." The Rosgen classification is probably best applied as a communication tool to describe channel form but, in combination with "natural channel design" techniques, are not diagnostic of how to mitigate channel instability or predict equilibrium morphologies. For this, physically based, mechanistic approaches that rely on quantifying the driving and resisting forces that control active processes and ultimate channel morphology are better suited as the physics of erosion, transport, and deposition are the same regardless of the hydro-physiographic province or stream type because of the uniformity of physical laws. © 2007 American Water Resources Association.

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Published In

Journal of the American Water Resources Association

DOI

ISSN

1093-474X

Publication Date

October 1, 2007

Volume

43

Issue

5

Start / End Page

1117 / 1131

Related Subject Headings

  • Environmental Engineering
  • 40 Engineering
  • 37 Earth sciences
  • 0907 Environmental Engineering
  • 0905 Civil Engineering
  • 0406 Physical Geography and Environmental Geoscience
 

Citation

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Simon, A., Doyle, M., Kondolf, M., Shields, F. D., Rhoads, B., & McPhillips, M. (2007). Critical evaluation of how the Rosgen classification and associated "natural channel design" methods fail to integrate and quantify fluvial processes and channel response. Journal of the American Water Resources Association, 43(5), 1117–1131. https://doi.org/10.1111/j.1752-1688.2007.00091.x
Simon, A., M. Doyle, M. Kondolf, F. D. Shields, B. Rhoads, and M. McPhillips. “Critical evaluation of how the Rosgen classification and associated "natural channel design" methods fail to integrate and quantify fluvial processes and channel response.” Journal of the American Water Resources Association 43, no. 5 (October 1, 2007): 1117–31. https://doi.org/10.1111/j.1752-1688.2007.00091.x.
Simon A, Doyle M, Kondolf M, Shields FD, Rhoads B, McPhillips M. Critical evaluation of how the Rosgen classification and associated "natural channel design" methods fail to integrate and quantify fluvial processes and channel response. Journal of the American Water Resources Association. 2007 Oct 1;43(5):1117–31.
Simon, A., et al. “Critical evaluation of how the Rosgen classification and associated "natural channel design" methods fail to integrate and quantify fluvial processes and channel response.” Journal of the American Water Resources Association, vol. 43, no. 5, Oct. 2007, pp. 1117–31. Scopus, doi:10.1111/j.1752-1688.2007.00091.x.
Simon A, Doyle M, Kondolf M, Shields FD, Rhoads B, McPhillips M. Critical evaluation of how the Rosgen classification and associated "natural channel design" methods fail to integrate and quantify fluvial processes and channel response. Journal of the American Water Resources Association. 2007 Oct 1;43(5):1117–1131.
Journal cover image

Published In

Journal of the American Water Resources Association

DOI

ISSN

1093-474X

Publication Date

October 1, 2007

Volume

43

Issue

5

Start / End Page

1117 / 1131

Related Subject Headings

  • Environmental Engineering
  • 40 Engineering
  • 37 Earth sciences
  • 0907 Environmental Engineering
  • 0905 Civil Engineering
  • 0406 Physical Geography and Environmental Geoscience