STEADY UNIFORM FLOW 



range of circumstances is beyond the scope of this book. If more 

 information is needed, the references listed in Table 101 should be 

 consulted. 



TABLE 101 

 Values of " n " for use in Manning's or Kutter's Formulas 



Compiled from various sources. For more detailed information, see F. C. Scobey, 

 " Flow of Water in Flumes," U.S.D.A. Tech. Bull. 393, and " The Flow of Water in 

 Irrigation and Similar Canals," U.S.D.A. Tech. Bull. 652, also C. E. Ramser, " Flow 

 of Water in Drainage Channels," U.S.D.A. Tech. Bull. 129, and Ivan E. Houk, 

 " Calculation of Flow in Open Channels," Miami Conservancy District, Technical 

 Reports, Part IV. 



0.009 and 0.010 

 0.011 and 0.012 

 0.013 



0.014 



0.015 



0.016 



0.017 

 0.018-0.025 



0.016-0.017 



0.020 



0.0225 



0.025 



0.030 



0.035 

 0.040-0.050 



0.050-0.150 



Very smooth and true surfaces, without projections. Clean new 

 glass, pyralin, or brass, with straight alignment. 

 Smoothest clean wood, metal, or concrete surfaces, without pro- 

 jections, and with straight alignment. 



Smooth wood, metal, or concrete surfaces without projections, free 

 from algae or insect growth, and with reasonably straight align- 

 ment. 



Good wood, metal, or concrete surfaces with very small projections, 

 with some curvature, with slight insect or algae growth, or with 

 slight gravel deposition. Shot concrete surfaced with troweled 

 mortar. 



Wood with algae and moss growth, concrete with smooth sides but 

 roughly troweled or shot bottom, metal with shallow projections. 

 Same with smoother surface but excessive curvature. 

 Metal flumes with large projections into the section. Wood or 

 concrete with heavy algae, or moss growths. 

 Shot concrete, not troweled, but fairly uniform. 

 Metal flumes with large projections into the section and excessive 

 curvature, growths, or accumulated debris. 



Smoothest natural earth channels, free from growths, with straight 

 alignment. 



Smooth natural earth, free from growths, little curvature. Very 

 large canals in good condition. 



Average, well-constructed, moderate-sized earth canal in good 

 condition. 



Very small earth canals or ditches in good condition, or larger 

 canals with some growth on banks or scattered cobbles in bed. 

 Canals with considerable aquatic growth. Rock cuts, based on 

 average actual section. Natural streams with good alignment, 

 fairly constant sect ion . Large flood way channels, well maintained . 

 Canals half choked with moss growth. Cleared but not continu- 

 ously maintained floodways. 



Mountain streams in clean loose cobbles. Rivers with variable 

 section and some vegetation growing in banks. Canals with very 

 heavy aquatic growths. 



Natural streams of varying roughness and alignment. The highest 

 values for extremely bad alignment, deep pools, and vegetation, or 

 for floodways with heavy stand of timber and underbrush. 



