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SURFACE-WATER FIELD TECHNIQUES


Verified Roughness Characteristics of Natural Channels

Most hydraulic computations related to indirect estimates of discharge require an evaluation of the roughness characteristics of the channel. In the absence of a satisfactory quantitative procedure this evaluation remains chiefly an art. The ability to evaluate roughness coefficients must be developed through experience. One means of gaining this experience is by examining and becoming acquainted with the appearance of some typical channels whose roughness coefficients are known.

The photographs and data linked to this page represent a wide range of channel conditions found in the Western United States. Familiarity with the appearance, geometry, and roughness characteristics of these channels will improve your ability to select roughness coefficients for other channels. We will contiune to link descriptions of additional sites to this page as verification data become available. (Text above modified from USGS Water Supply Paper 1849, by H.H. Barnes, Jr.))

You can view data related to selected roughness coefficients by clicking on a site name, or photo, below:

 

Manning's n-value

Stream

Photo

Photo 1

Photo 2

 

0.024

Columbia River at Vernita, Washington

Photo of n.024 upstream
Photo of N .024 downstream

0.028

Clark Fork at St. Regis, Montana

Photo of n.028 upstream
Photo of N .028 downstream

0.030

Clark Fork above Missoula, Montana

Photo of n.030 upstream
Photo of N .030 downstream
0.032

Salt River below Stewart Mountain Dam, Arizona

Photo of n.043 upstream
Photo of N .032 downstream
0.033

Clearwater River at Kamiah, Idaho

Photo of n.033 upstream
Photo of N .033 downstream
0.036

West Fork Bitterroot River near Conner, Montana

Photo of n.036 upstream
Photo of N .036 downstream
0.037

Wenatchee River at Plain, Washington

Photo of N.037 upstream
Photo of N .037 downstream
0.038

Moyie River at Eastport, Idaho

Photo of N .038 upstream
Photo of N .038 downstream
0.038

Spokane River at Spokane, Washington

Photo of N .038 upstream
Photo of N .038 downstream
0.041

Middle Fork Flathead River near Essex, Montana

Photo of N .041 upstream
Photo of N .041 downstream
0.043

Catherine Creek near Union, Oregon

Photo of N .043 upstream
Photo of N .043 downstream
0.043

Chiwawa River near Plain, Washington

Photo of N .043 upstream
Photo of N .043 downstream
0.043

Grande Ronde River at La Grande, Oregon

Photo of N .043 upstream
Photo of N .043 downstream
0.045; 0.073

Provo River near Hailstone, Utah

Photo of N .045 upstream
Photo of N .045 downstream
 0.050

Clear Creek near Golden, Colorado 

Photo of N .050 upstream
Photo of N .050 downstream
 0.051

South Fork Clearwater River near Grangeville, Idaho 

Photo of N .051 upstream
Photo of N .051 downstream 
0.053; 0.079

Cache Creek near Lower Lake, California

Photo of N .053 upstream
Photo of N .053 downstream
0.057

Mission Creek near Cashmere, Washington

Photo of N .057 upstream
Photo of N .057 downstream
0.060

Rock Creek Canal near Darby, Montana

Photo of N .060 upstream
Photo of N .060 downstream
0.065

Merced River at Happy Isles Bridge, near Yosemite, California

Photo of N .065 upstream
Photo of N .065 downstream
0.073

Boundary Creek near Porthill, Idaho

Photo of N .073 upstream
Photo of N .073 downstream
0.075

Rock Creek near Darby, Montana

(Missing)
Photo of N .075 downstream