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<br />n <br /> <br />EXPLANA liON <br /> <br />NUMBER REFERS TO SUBAREA <br /> <br />MANNING'S ROUGHNESS COEFFI- <br />CIENT <br /> <br />COMPOSITE n VALUE FOR THE <br />CHANNEL <br /> <br />WETTED PERIMETER, IN FEET, FOR <br />EACH ROUGHNESS AREA <br /> <br />ROUGHNESS COEFFICIENT'S FOR <br />EACH WETTED PERIMETER <br /> <br />n, <br /> <br />P"P"P3 <br /> <br />nj,n"n3 <br /> <br />40 <br /> <br />>- <br />w <br />w <br />~ <br /> <br /> <br />Water surface <br /> <br /> <br />P,=15 feet <br />n,::::Q.15 <br /> <br />P3=22 feet <br />n]=O.15 <br /> <br /> <br />2 <br /> <br />n=O.12 <br /> <br />3 <br />nc=O.052 <br /> <br />30 <br /> <br />n=O.05 <br /> <br />10 <br /> <br />P3=165 teet <br />n ,=0.030 <br /> <br />o <br />o 100 <br />VERTICAL EXAGGERATION X 5 <br /> <br />I' (1/ If I <br /> <br />200 <br /> <br />300 400 <br />DISTANCE, IN FEET <br /> <br />500 <br /> <br />600 <br /> <br />Ftgure 4.--Cross section of a hypothetical channel and flood plain <br />showing subdivisions based on geometry and roughness. <br /> <br />11 <br />