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<br />Table 4.--Qutline and example of procedures for determining n values <br />for a hypothetical channel and flood plain--Continued <br /> <br />SECTION l--Continued <br /> <br />Channel Roughness (steps 3-13)--COntinued <br /> <br />Step <br /> <br />Factors on which decisions are <br />based and the results <br /> <br />Item to be determined or <br />operation to be performed <br /> <br />11 <br /> <br />Add adjustments for entire <br />channel <br /> <br />Vegetation (n4)--weeds and supple <br />seedlings along bottom of channe 1, <br />n4 = 0.005 <br />Meander is minor, m = 1.00 <br />n = (nb + nl + n2 + n3 + n4)m <br />n = (0.025 + 0 + 0 + 0 + 0.005)1.00 <br />n = 0.030. <br /> <br />12 <br /> <br />Compare with other streams <br /> <br />None. <br /> <br />13 <br /> <br />Check flow regime <br /> <br />SECTION 2 <br /> <br />Not applicable. <br /> <br />1 Extent of reach From midway between sections 1 and <br />2 to midway between sections 2 and <br />3. Designated as reach B (fig. <br />23. ) <br /> <br />2 Subdivision of cross section Flow remains in channel, no over- <br />bank flood-plain flow. The channel <br />is composed of distinct bands, each <br />having a different roughness. <br />Derive n by weighting segments. <br /> <br />3 <br /> <br />Channel Roughness (steps 3-13) <br /> <br />(a) Type of channel <br /> <br />(b) Conditions during flow <br />event <br /> <br />(c) Comparable streams <br /> <br />COmbinations of sand and stable <br />channel. Consider that channel <br />reacts as a stable channel. <br /> <br />Some movement of sand may have <br />occurred during the peak flow, but <br />assume that channel conditions are <br />representative of those that <br />existed during the peak. <br /> <br />None. <br /> <br />4 <br /> <br />Roughness factors <br /> <br />(1) Bedrock--may be accounted for <br />by adding an adjustment factor to <br />the n value for the bed or as a <br />separate segment. Use latter. <br /> <br />53 <br />