On-Line Manning's N Database
Select Channel Description
PVC Sewer Pipe
Smooth, straight surfaces; enameled or glazed coating; glass; lucite; brass
Planed and fitted lumber boards; smooth metal; cement plaster; smooth tar or paint coating
Smooth mortar (1/3 sand) without projections, in straight alignment
Fitted, but unplaned boards; steel trowled concrete, in straight alignment
Straight, clean, smooth surfaces without projections; good boards; carefully built brich wall; wood trowled concrete; smooth, dressed ashlar (masonry)
Good wood, metal, or concrete surfaces with some curvature, very small projections, slight moss or algae growth or gravel deposition; shot concrete surfaced with trowled mortar
Rough brick; medium quality cut stone surface; wood with algae or moss growth; rough concrete; riveted steel
Very smooth and straight earth channels, free from growth; stone rubble set in cement; shot, untroweled concrete; deteriorated brick wall; exceptionally well excavated and surfaced channel cut in natural rock
Well-built earth channels covered with thick, uniform silt deposits; metal flumes with excessive curvature, large projections, accumulated debris
Smooth, well-packed earth; rough stone walls; channels excavated in solid, soft rock; little curving channels in solid loess, gravel, or clay with silt deposits, free from growth and in average condition
Deteriorating uneven metal flume with curvatures and debris; very large canals in good condition
Small, human-made earth channels in well-kept condition; straight natural streams with rather clean, uniform bottoms without pools and flow barriers, cavings, and scours of the banks
Ditches; below-average human-made channels with scattered cobbles in bed
Well-maintained large floodway; unkept artifical channelswith scours, slides, considerable aquatic growth; natural stream with good alignment and fairly constant cross section
Permanent alluvial rivers with moderate changes in cross section, average stage; slightly curving intermittent streams in very good condition
Small deterioriated artifical channels, half choked with aquatic growth; winding river with clean bed, but with pools and shallows
Irregularly curving permanent alluvial stream with smooth bed; straight natural channels with uneven bottom, sand bars, dunes, few rocks and underwater ditches
Lower section of mountainous streams with well-developed channel with sediment deposits; intermittent streams in good condition; deteriorated artifical channels, with moss and reeds, rocks, and slides
Artifical earth channels partially obstructed with debris, roots, and weeds; irregularly meandering rivers with partially grown-in or rocky bed; developed flood plains with high grass and bushes
Mountain ravines; fully ingrown small artifical channel; flat flood plains crossed by deep ditches
Mountain creeks with waterfalls and steep ravines; irregular flood plains; weedy and sluggish natural channels obstructed with trees
Rough mountain creeks; swampy, heavily vegetated rivers with logs and driftwood on the bottom; flood plain forests with pools
Mudflows; very dense flood plain forests; watershed slopes
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Clean, straight, full stage, no rifts or deep pools
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Same as above, but more stones and weeds
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Clean, winding, some pools and shoals
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Same as above, but some stones and weeds
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Same as above, but lower stages, more ineffective slopes and sections
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Clean, winding, some pools and shoals, some weeds and many stones
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Sluggish reaches, weedy, deep pools
Minor Streams (top width at flood stage <30 meters) ; Streams on plain; Very weedy reaches, deep pools, or floodways with heavy stand of timber and underbrush
Mountain streams, no vegetation in channel, banks usually steep, trees and brush along banks submerged at high stages: Bottom: gravel, cobbles, and few boulders
Mountain streams, no vegetation in channel, banks usually steep, trees and brush along banks submerged at high stages: Bottom: cobbles with large boulders
Flood Plains ; Pasture, no brush: Short grass
Flood Plains ; Pasture, no brush: High grass
Flood Plains ; Cultivated areas: No crop
Flood Plains; Cultivated areas: Mature row crops
Flood Plains ; Cultivated areas: Mature field crops
Floodplains; Brush: Scattered brush, heavy weeds
Floodplains; Brush: Light brush and trees, in winter
Floodplains; Brush: Light brush and trees, in summer
Floodplains; Brush: Medium to dense brush, in winter
Floodplains; Brush: Medium to dense brush, in summer
Floodplains; Trees: Dense willows, summer, straight
Floodplains; Trees: Cleared land with tree stumps, no sprouts
Floodplains; Trees: Cleared land with tree stumps with heavy growth of sprouts
Floodplains; Trees: Heavy stand of timber, a few down trees, little undergrowth, flood stage below branches
Floodplains; Trees: Heavy stand of timber, a few down trees, little undergrowth, flood stage below branches , but flood stage reaching branches
Major Streams (top width at flood stage >30 meters) ; Regular section with no boulders or brush
Major Streams (top width at flood stage >30 meters) ; Irregular and rough section
Major Streams (top width at flood stage >30 meters) ;Lined Channels ; Concrete-lined
Major Streams (top width at flood stage >30 meters) ; Lined Channels ; Concrete rubble
Major Streams (top width at flood stage >30 meters) ;Unlined Channels ; Earth, straight and uniform
Major Streams (top width at flood stage >30 meters) ;Unlined Channels ; Winding and sluggish
Major Streams (top width at flood stage >30 meters) ;Unlined Channels ;Rocky beds, weeds on bank
Major Streams (top width at flood stage >30 meters) ;Unlined Channels ;Earth bottom, rubble sides
Major Streams (top width at flood stage >30 meters) ;Unlined Channels ; Rock cuts