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Mannings N: table 2
2. random stone in mortar to 3. mature field crops
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 | 2. random stone in mortar | 0.024 | 0.017 | 0.02 | d. Concrete bottom float finish with sides of: |
| table 2 | 2. random stone mortar | 0.026 | 0.02 | 0.023 | e. Gravel bottom with sides of: |
| table 2 | 3. cement rubble masonry, plastered | 0.024 | 0.016 | 0.02 | d. Concrete bottom float finish with sides of: |
| table 2 | 3. dense weeds or aquatic plants in deep channels | 0.04 | 0.03 | 0.035 | b. Earth winding and sluggish |
| table 2 | 3. dry rubble or riprap | 0.036 | 0.023 | 0.033 | e. Gravel bottom with sides of: |
| table 2 | 3. finished, with gravel on bottom | 0.02 | 0.015 | 0.017 | c. Concrete |
| table 2 | 3. gravel, uniform section, clean | 0.03 | 0.022 | 0.025 | a. Earth, straight, and uniform |
| table 2 | 3. light brush and trees, in summer | 0.08 | 0.04 | 0.06 | c. Brush |
| table 2 | 3. mature field crops | 0.05 | 0.03 | 0.04 | b. Cultivated areas |
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