Manning's Equation & Channel Design

Channel Parameters

Q = (1.486 / n) * A * R^2/3 * S^1/2 (US)
Q = (1.0 / n) * A * R^2/3 * S^1/2 (Metric)

Unit System

Target Discharge ($Q$)

Manning's Roughness Coefficient ($n$)

Bed Slope ($S$)

Side Slope ($z$ - Horizontal per 1 Vertical)

Freeboard Depth ($F_b$)

Calculated Bed Width ($b$): -

Water Depth ($y$): -

Top Width at Water Surface ($T_w$): -

Top Width at Bank Level ($T_b$): -

Total Channel Depth ($D = y + F_b$): -

Wetted Perimeter ($P$): -

Cross-Sectional Area ($A$): -

Hydraulic Radius ($R$): -

Actual Computed Discharge ($Q_{act}$): -