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<br />Table 2.--Factors that effect roughness of the channel <br />[Modified from Aldridge and Garrett, 1973, table 2J <br /> <br />Channel conditions <br /> <br />Example <br /> <br />n value <br />adjustmentY <br /> <br />Smooth <br /> <br />0.000 <br /> <br />Oompares to the smoothest channel attainable in a glven <br />bed material. <br /> <br />Minor <br /> <br />0.001-0.005 <br /> <br />Legree of <br />irregularity <br />(nl) <br /> <br />Moderate <br /> <br />0.006-0.010 <br /> <br />Compares to carefully dredged channels in good condition <br />but having slightly eroded or scoured side slopes. <br /> <br />Compares to dredged channels having moderate to con- <br />siderable bed roughness and moderately sloughed or <br />eroded side slopes. <br /> <br />'" <br /> <br />Severe <br /> <br />0.011-0.020 <br /> <br />Badly sloughed or scalloped banks of natural streams; <br />badly eroded or sloughed sides of canals or drainage <br />channels; unshaped, jagged, and irregular surfaces of <br />channels in rock. <br /> <br />Gradual <br /> <br />0.000 <br /> <br />Size and shape of channel cross sections change gradually. <br /> <br />Variation in <br />channel cross <br />section <br />(n2) <br /> <br />Alternating 0.001-0.005 <br />occasionally <br /> <br />Large and small cross sections alternate occasionally, or <br />the main flow occasionally shifts from side to side <br />owing to changes in cross-sectional shape. <br /> <br />Alternating <br />frequently <br /> <br />0.010-0.015 <br /> <br />Large and small cross sections alternate frequently, or <br />the main flow frequently shifts from side to side oWlng <br />to changes in cross-sectional shape. <br />