Calculate flow velocity and discharge using Manning's Equation.
Channel Parameters
m²
m
Flow Results
Enter parameters to calculate flow
About this calculator
Quick Reference
vMean Velocity (m/s)
nManning's Coefficient
RHydraulic Radius (m)
SSlope of Energy Line (m/m)
QFlow Discharge (m³/s)
Overview
Open channel flow occurs when the liquid has a free surface exposed to the atmosphere. Manning's Equation is the most widely used formula for uniform flow in open channels.
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Pro Tips
Hydraulic Radius (R) = Area / Wetted Perimeter.
The slope (S) is the change in elevation divided by the length.
Manning's n depends on the channel material and condition.
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Fun Facts
"The formula was developed by Robert Manning in 1889."
"It is an empirical formula, meaning it's based on experimental data rather than pure physical derivation."
"Manning's formula is also used for flow in partially filled pipes."
