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Stream Power Formulas and Calculator

Civil Engineering Design and Engineering
Fluids Engineering and Design

Stream Power Formulas and Calculator

Stream power is a geomorphology concept that is a measure of the available energy a stream has for moving sediment, rock, or woody material.

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For a cross section, the total stream power per unit length of channel may be formulated as:

Ω = γ Q Sf
Ω = γ v w d Sf


γ = unit weight of water (lb/ft3)
Q = discharge (ft3/s)
Sf = energy slope (ft/ft)
v = velocity (ft/s)
w = channel width (ft)
d = hydraulic depth (ft)

English units are pounds per second per foot of channel length. A second formulation, unit stream power, is the stream power per unit of bed area:

Ω = τ v

τ = bed shear stress
v = average velocity

A third formulation relates stream power per unit weight of water:

Ω = Sf v

where the terms are as previously defined.


National Engineering Handbook, United States Department of Agriculture
Part 654 STream Restoration Design