Environment, Coasts, Oceans, & Infrastructure

Table 3-1 of NRCS TR-55 provides Manning's n values for sheet flow.  Can anyone provide photograph examples of what the surface descriptions might look like for for Woods, light underbrush (n=0.4) vs. dense underbrush (n=0.8)?  I am trying to make a decision on what is best for a time of concentration calculation for a wooded site.

Thank you!

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Christopher Cloutet P.E., M.ASCE
Civil Engineer
Slidell LA
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Try: https://pubs.er.usgs.gov/publication/wsp2339

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Andrew Scott P.E., M.ASCE
Virginia Departement of Transportation
Suffolk VA
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That's an excellent resource!

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Maria Price P.E., M.ASCE
Engineering Manager
City of Chattanooga
Chattanooga TN
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Original Message:
Sent: 10-09-2020 09:39 AM
From: Andrew Scott
Subject: Mannings Roughness Coefficient (n) for Woods (Light Underbrush vs. Dense Underbrush)

Try: https://pubs.er.usgs.gov/publication/wsp2339

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Andrew Scott P.E., M.ASCE
Virginia Departement of Transportation
Suffolk VA
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In addition to the excellent USGS source, there is a paper in the Encyclopedia of Coastal Science. The Seabed Roughness discusses roughness in current, wave and wave-current environments, and presents equivalence of different coefficients – Manning, Chezy and others. It does not specifically address woody waterways, typical of your case – but you may find it useful, have a look.

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Dilip

Website

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Google Scholar

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Dr. Dilip Barua, Ph.D, P.Eng, M. ASCE
Vancouver, BC, Canada
https://widecanvas.weebly.com
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Thank you for these excellent references, but I am still looking for simply just a couple of pictures to show the differences between light underbrush vs dense underbrush. Any help is greatly appreciated.

Thanks again.

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Christopher Cloutet P.E., M.ASCE
Civil Engineer
Slidell LA
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Chris: if you have not used it already, perhaps the 1991/1994 USACE manual: EM 1110-2-1601 (Hydraulic Design of Flood Control Channels) may help your specific need. In Chapter 5, it details methods to estimate/predict 'n'.

Among others, it indicates values and methods for vegetative channel areas. If you do not have the manual, it is freely downloadable from USACE EM website: https://www.publications.usace.army.mil

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Dilip

Website

ORCID ID

Google Scholar

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Dr. Dilip Barua, Ph.D, P.Eng, M. ASCE
Vancouver, BC, Canada
https://widecanvas.weebly.com
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Thank you. I am adding these resources to my personal library.

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Christopher Cloutet P.E., M.ASCE
Civil Engineer
Slidell LA
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Hi Chris, the USGS publication has several photos with measured n values. Therese
https://pubs.er.usgs.gov/publication/wsp2339

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Therese Baer P.E., M.ASCE
President
Baer Engineering and Enviro Consulting
Austin TX
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Original Message:
Sent: 10-12-2020 02:34 PM
From: Christopher Cloutet
Subject: Mannings Roughness Coefficient (n) for Woods (Light Underbrush vs. Dense Underbrush)

Thank you. I am adding these resources to my personal library.

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Christopher Cloutet P.E., M.ASCE
Civil Engineer
Slidell LA
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