Chezy's formula.

$v = c \sqrt {mi}$

where,

v = velocity of flow

c = changes constant

i = bed slope

m = hydraulic mean depth = $\frac{A}{P}$

p = perimeter = b + 2d

A = area.

Discharge through open channel by chezy's formula.

Q = Area x Velocity = A x Y

$\therefore$ The chezy's equation becomes

$= A \times c \sqrt{mi}$

OR

Q = Ac $\sqrt{mi}$