v = 1/n x R^{2/3 }x S^{1/2} |
Where : |
n = coefficient
of roughness (typically 0.3) |
v = Water velocity down the channel (m
/ sec) = flow (m^{3}sec^{-1}) / cross sectional area
(m^{2}) |
R = Hydraulic radius (m) = cross sectional
area (m^{2}) / wetted
perimeter (m) |
S = Gradient of channel (m / 100m) |