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

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

$s$ = sine of slope