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Table 10. Hanning I 8 roughness coefficient, n, for selected values of mean depth and median bed material size. Mean Median diameter of bed material, Dao, in feet depth, d Fine Medium Coarse Medium Coarse Sma 11 Medium Large a sand sand sand Fine ..ravel gravel gravel cobble cobble cobble Boulders (ft) 0.0005 0.001 0.005 0.010 0.015 0.020 0.10 0.20 0.30 0.40 0.50 1.0 1.25 1.50 1 0.019 0.019 0.019 0.021 0.022 0.024 0.035 0.044 0.053 0.061 0.068 0.117 0.151 0.198 2 .021 .021 .021 .021 .022 .023 .032 .039 .045 .050 .054 .077 .089 .101 3 .022 .022 .022 .022 .022 .023 .032 .038 .042 .046 .050 .066 .074 .082 4 .023 .023 .023 .023 .023 .023 .031 .036 .041 .044 .047 .061 .068 .074 5 .024 .024 .024 .024 .024 .024 .031 .036 .040 .043 .046 .058 .064 .069 6 .025 .025 .025 .025 .025 .025 .031 .035 .039 .042 .045 .056 .061 .066 7 .026 .026 .026 .026 .026 .026 .030 .035 .038 .041 .044 .054 .059 .063 8 .026 .026 .026 .026 .026 .026 .030 .035 .038 .041 .053 .053 .057 .061 9 .027 .027 .027 .027 .027 .027 .030 .035 .038 .041 .043 .052 .056 .060 " 10 .027 .027 .027 .027 .027 .027 .030 .035 .038 .040 .042 .051 .055 .059 " 12 .028 .028 .028 .028 .028 .028 .030 .034 .037 .040 .042 .050 .054 .057 14 .029 .029 .029 .029 .029 .029 .030 .034 .037 .039 .042 .049 .053 .056 15 .029 .029 .029 .029 .029 .029 .030 .034 .037 .039 .041 .049 .052 .055 20 .031 .031 .031 .031 .031 .031 .031 .034 .037 .039 .041 .048 .050 .053 25 .032 .032 .032 .032 .032 .032 .032 .034 .036 .039 .040 .047 .050 .052 30 .033 .033 .033 .033 .033 .033 .033 .034. .036 .038 .040 .046 .049 .051 35 .033 .033 .033 .033 .033 .033 .033 .034 .036 .038 .040 .046 .048 .050 40 .034 .034 .034 .034 .034 .034 .034 .034 .036 .038 .040 .046 .048 .050 Relationships used io preparing table, 0.0926 d 0.187 Equation 12 o = a for 1. 5< d ID&o< 185 0.794+1.85 log d ID&O a a Equation 17 n = 0.0185d 0.187 for 185< d ID&o< 30,000 a a