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Mannings N: table 2
3. same as above, but with heavy growth of sprouts to 4. unfinished
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 | 3. same as above, but with heavy growth of sprouts | 0.08 | 0.05 | 0.06 | d. Trees |
| table 2 | 3. same as above, highest stage of flow | 0.11 | 0.045 | 0.07 | e. Channels not maintained, weeds and brush uncut |
| table 2 | 3. unplaned | 0.015 | 0.011 | 0.013 | b. Wood |
| table 2 | 4. cement rubble masonry | 0.03 | 0.02 | 0.025 | d. Concrete bottom float finish with sides of: |
| table 2 | 4. dense brush, high stage | 0.14 | 0.08 | 0.1 | e. Channels not maintained, weeds and brush uncut |
| table 2 | 4. earth bottom and rubble sides | 0.035 | 0.028 | 0.03 | b. Earth winding and sluggish |
| table 2 | 4. heavy stand of timber, a few down trees, little undergrowth, flood stage below branches | 0.12 | 0.08 | 0.1 | d. Trees |
| table 2 | 4. medium to dense brush, in winter | 0.11 | 0.045 | 0.07 | c. Brush |
| table 2 | 4. plank with battens | 0.018 | 0.012 | 0.015 | b. Wood |
| table 2 | 4. unfinished | 0.02 | 0.014 | 0.017 | c. Concrete |
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