Kutter's formula

A formula for evaluating the coefficient, C, in the following Chezy formula for the mean velocity of the current in a stream.

v=C\sqrt{rs}

where

v = velocity in feet per second

C = a coefficient

C=\frac{41.6+\frac{1.811}{n}+\frac{0.00281}{s}}{1+(41.6+\frac{0.00281}{s})\frac{n}{\sqrt{r}})}

r = hydraulic radius

s = sine of slope

and n = coefficient of roughness