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<br />Table 11. Hanning's roughness coefficient, n, for selected <br />values of channel slope. <br /> <br />(Adapted from Jarrett, 1984. Equation given by Jarrett is <br />n=0.3955fo.3a R-O.16. Because R is approximately equal to da, <br />and 5f is approximately equal to 5 . the equation has been <br />. w <br />modified to n = 0.3955 0.38 d -0.16. Values of n for mean <br />w a <br />depths greater than 7 ft are based on an extension of the <br />relationship given by equation 19 and may not be reliable] <br /> <br />Mean <br />depth, <br />d (ft) <br />a <br /> <br />0.001 <br /> <br />Channel slope (ft/ft) <br />0.003 0.005 0.007 <br /> <br />0.100 <br /> <br />1 <br />2 <br />3 <br />4 <br />5 <br />6 <br />7 <br /> <br />0.028 0.043 0.052 0.059 0.163 <br /> .038 .047 .053 .146 <br /> .036 .044 .050 .136 <br /> .034 .042 .047 .130 <br /> .033 .040 .046 .126 <br /> .033 .039 .044 .122 <br /> .031 .038 .043 .119 <br /> .031 .037 .042 .117 <br /> .030 .037 .042 .114 <br /> .030 .036 .041 .112 <br /> .029 .035 .040 .109 <br /> .028 .034 .039 .107 <br /> .028 .034 .038 .105 <br /> .032 .037 .101 <br /> .031 .036 .097 <br /> .030 .034 .094 <br /> .029 .034 .092 <br /> .029 .033 .090 <br /> <br />8 <br />9 <br />10 <br />12 <br />14 <br />15 <br />20 <br />25 <br />30 <br />35 <br />40 <br /> <br />77 <br />