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Froehlich: Developed based on diverse data from 15 sites, described by Barnes (1967), for which bed-material particle sizes are included (Coon, 1995).

Barnes, H.H., 1967, Roughness characteristics of natural channels: U.S. Geological Survey Water-Supply Paper 1849. 213 p.

Coon, W.F., 1995, Estimates of roughness coefficients for selected natural stream channels with vegetated banks in New York: U.S. Geological Survey Open-File Report 93-707, 161 p.

Jobson, H.E., and Froehlich, D.C., 1988, Basic hydraulic principles of open-channel flow: U.S. Geological Survey Open-File Report 88-707, 150 p.

n N-value.
R Hydraulic radius in feet.
d50 Bed material diameter corresponding to that 50 percent of the material is finer, unit in feet.
T Top width of stream in feet
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