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Mannings N: table 2
1. planed, untreated to 2. dry rubble
Manning's n roughness coefficients for open channels and closed conduits — used in hydraulic flow calculations
| section | description | n max (dimensionless) | n min (dimensionless) | n normal (dimensionless) | subcategory |
|---|---|---|---|---|---|
| table 2 | 1. planed, untreated | 0.014 | 0.01 | 0.012 | b. Wood |
| table 2 | 1. scattered brush, heavy weeds | 0.07 | 0.035 | 0.05 | c. Brush |
| table 2 | 1. smooth and uniform | 0.04 | 0.025 | 0.035 | d. Rock cuts |
| table 2 | 1. trowel finish | 0.015 | 0.011 | 0.013 | c. Concrete |
| table 2 | 1.short grass | 0.035 | 0.025 | 0.03 | a. Pasture, no brush |
| table 2 | 2. clean bottom, brush on sides | 0.08 | 0.04 | 0.05 | e. Channels not maintained, weeds and brush uncut |
| table 2 | 2. clean, after weathering | 0.025 | 0.018 | 0.022 | a. Earth, straight, and uniform |
| table 2 | 2. cleared land with tree stumps, no sprouts | 0.05 | 0.03 | 0.04 | d. Trees |
| table 2 | 2. dry rubble | 0.035 | 0.023 | 0.032 | g. Masonry |
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