|
Design
Use Values of Manning's n
| Channel Material |
n |
| clean, uncoated cast iron |
0.013-0.015 |
| clean, coated cast iron |
0.012-0.014 |
| dirty, tuberculed cast iron |
0.015-0.035 |
| riveted steel |
0.015-0.017 |
| lock-bar and welded |
0.012-0.013 |
| galvanized iron |
0.015-0.017 |
| brass and glass |
0.009-0.013 |
| wood stave |
| small diameter |
0.011-0.012 |
| large diameter |
0.012-0.013 |
| concrete |
| with rough joints |
0.016-0.017 |
| dry mix, rough forms |
0.015-0.016 |
| wet mix, steel forms |
0.012-0.014 |
| very smooth, finished |
0.011-0.012 |
| vitrified sewer |
0.013-0.015 |
| common-clay drainage tile |
0.012-0.014 |
| asbestos |
0.011 |
| planed timber |
0.011 |
| canvas |
0.012 |
| unplaned timber |
0.014 |
| brick |
0.016 |
| rubble masonry |
0.017 |
| smooth earth |
0.018 |
| firm gravel |
0.023 |
| corrugated metal pipe |
0.022 |
| natural channels, good condition |
0.025 |
| natural channels with stones and weeds |
0.035 |
| very poor natural channels |
0.060 |
|
