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Table 1-5.7 "n" and "k" Values Used in Time Calculations for Hydrographs <br /> sheet Flow (initial 300 feet of travel) <br /> Surface n <br /> Smooth surfaces(concrete, asphalt, gravel, compacted soil) 0.011 <br /> Fallow fields or loose soil 0.05 <br /> Short prairie grass and lawns 0.17 <br /> Dense grasses 0.15 <br /> Bermuda grass 0.24 <br /> Range(natural) 0.41 <br /> Woods or forest with light underbrush 0.13 <br /> Woods or forest with dense underbrush 0.40 <br /> Shallow Concentrated Flow (After the initial 300 feet of sheet flow; R=0.1) <br /> Surface k <br /> Forest with heavy ground litter and meadows (n=0.10) 3 <br /> Brushy ground with some trees (n=0.060) 5 <br /> Fallow or minimum tillage cultivation(n= 0.040) 8 <br /> High grass(n=0.035) 9 <br /> Short grass, pasture and lawns (n= 0.030) 11 <br /> Nearly bare ground(n=0.25) 13 <br /> Waved and gravel areas (n= 0.012) 27 <br /> —Intermittent Channel Flow (At the beginning of visible channels, R=0.2) <br /> Channel Type k <br /> Forested swale with heavy ground litter(n= 0.10) 5 <br /> Forested drainage course/ravine with defined channel bed(n=0.050) 10 <br /> Rock-lined waterway(n= 0.035) 15 <br /> Grassed waterway (n=0.030) 17 <br /> Earth-lined waterway(n=0.025) 20 <br /> CMP pipe(n=0.024) 21 <br /> Concrete pipe(n= 0.012) 42 <br /> Other waterways and pipe 0.508/n <br /> Continuous Stream Channel Flow(R=0.4) <br /> Channel Type k <br /> Meandering stream with some pools (n=0.040) 20 <br /> Rock-lined stream(n=0.035) 23 <br /> Grass-lined stream(n=0.030) 27 <br /> Other streams,man-made channels, and pipe 0.807/n <br /> 1-5-34 ` S <br />