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<br />Most of the resistance to flow in coarsE,-bed channels comes <br />from grain roughness and h'om bars. Tlhe following equations <br />can be uSI~d to predict thll Manning's roughness factor on <br />coarse-bed channels: <br /> <br />; <br /> <br />n = 10.0152 DJgS) <br /> <br />(1) <br /> <br />n = <br /> <br />0.113R (1/1>) <br /> <br />(1.16 + 2.0310g (O:JJ <br /> <br />(2) <br /> <br />; <br /> <br />where <br /> <br />0, = Particle sizefin'8ir than pE~rcent <br />I <br />050 = In equation (1), mm <br />OB4 = !In equation (2), m <br />R = Hydraulic radius. rn <br /> <br />Note that equation (2) may also be applied to sand-bed <br />channels in upper regime flow. <br /> <br />4, Water surface profiles <br /> <br />~Ai2-- <br />---. ---- <br />-:-:- ------:--- <br />''<,.;!'''MiJd ". :. ------- <br />Slope"'~~-_ <br />ep.,O,fT- <br />, 4 SloPe <br /> <br />-=- <br />-...;;:::'<~ - <br />-..""'- <br />~- .:st.';:--__ <br />Mild S10f~". ___--.:::::.- <br />~)te"- ~ <br />eps,_. _ <br />lOPe" <br /> <br />..lump <br />_ -___):SI--,-_ <br />~-- ---~-.- --- <br />"s~.. - -MJ:~'::]::::: <br />1JSlo',-__....~_ ump <br />'Po '...'."MHd SlOP; <br /> <br />3.17 <br />