Explain Chezy Manning Equation

v = 1.49/n (R)^0.67(S)^0.5    

R = hydraulic radius (ft) = Area/ wetted perimeter, R = D/4 for circular channels full and one-half full  

S = typically is the geometric slope (channel bottom). Sometimes it is the slope of the energy grade line. Units for both are (ft/ft).

 n = Manning's roughness coefficient based on the channel material. Values will be given or can be obtained in a table (dimensionless).