Discharge vs. river height by Manning's Equation

 

Discharge (Q)
	Height

 

The Manning Equation: $Q=VA=\frac{R^{\mathrm{2/3}}{S}^{\mathrm{1/2}}}{n}A$ Where: $R=\frac{\mathrm{Area}}{\mathrm{Wetted\; perimeter}}=\frac{\mathrm{Area}}{\mathrm{Wetted\; perimeter}}=\mathrm{20}$

For the river with dimensions:

 

S = 20		n = 20
Width (w) = 20		Bank angle = 20