EngiRef / Civil Engineering Formula

Manning's Equation

Manning's Equation: Velocity in open channel flow. A Hydraulics formula in civil engineering. Variables V, n, R and S, each with SI and imperial units.

Hydraulics

Specification

Name
Manning's Equation
Discipline
civil
Category
Hydraulics
LaTeX
V = \frac{1}{n}R^{2/3}S^{1/2}
Description
Velocity in open channel flow
Conditions
SI units, uniform flow in open channels
Can solve for
V, n, R, S
Tags
manning, open channel, flow, velocity

Variables

Variables for Manning's Equation
SymbolNameUnitSi UnitImperial Unit
VVelocitym/sm/sft/s
nManning's n
RHydraulic Radiusmmft
SChannel Slope