Given that, S0 = slope of the channel bottom, Sf = slope of the energy line and F = Froude no., the equation of gradually varied flow is expressed as
1
\(\frac{dy}{dx}=\frac{S_0-S_f}{1+F^2}\)
2
\(\frac{dy}{dx}=\frac{S_0-S_f}{1- F^2}\)
3
\(\frac{dy}{dx}=\frac{S_0+S_f}{1+F^2}\)
4
\(\frac{dy}{dx}=\frac{S_0+S_f}{1-F^2}\)