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Manning's Equation Formula

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Stream Velocity is the speed of the water in the stream. It is greatest in midstream near the surface and is slowest along the stream bed and banks due to friction. Check FAQs

v = (\frac{1}{n}) \cdot {(r H)}^{\frac{2}{3}} \cdot {(S̄)}^{\frac{1}{2}}

v - Stream Velocity?n - Manning’s Roughness Coefficient?r_H - Hydraulic Radius?S̄ - Bed Slope?

Manning's Equation Example

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Here is how the Manning's Equation equation looks like with Values.

Here is how the Manning's Equation equation looks like with Units.

Here is how the Manning's Equation equation looks like.

1.8223 = (\frac{1}{0.412}) \cdot {(0.23)}^{\frac{2}{3}} \cdot {(4)}^{\frac{1}{2}}

1.8223m/s = (\frac{1}{0.412}) \cdot {(0.23m)}^{\frac{2}{3}} \cdot {(4)}^{\frac{1}{2}}

1.8223 = (\frac{1}{0.412}) \cdot {(0.23)}^{\frac{2}{3}} \cdot {(4)}^{\frac{1}{2}}

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Manning's Equation Solution

Follow our step by step solution on how to calculate Manning's Equation?

FIRST Step Consider the formula

v = (\frac{1}{n}) \cdot {(r H)}^{\frac{2}{3}} \cdot {(S̄)}^{\frac{1}{2}}

Next Step Substitute values of Variables

∴

v = (\frac{1}{0.412}) \cdot {(0.23m)}^{\frac{2}{3}} \cdot {(4)}^{\frac{1}{2}}

Next Step Prepare to Evaluate

∴

v = (\frac{1}{0.412}) \cdot {(0.23)}^{\frac{2}{3}} \cdot {(4)}^{\frac{1}{2}}

Next Step Evaluate

∴

v = 1.82229214707637m/s

LAST Step Rounding Answer

∴

v = 1.8223m/s

Manning's Equation Formula Elements

Variables

Stream Velocity

Stream Velocity is the speed of the water in the stream. It is greatest in midstream near the surface and is slowest along the stream bed and banks due to friction.

Symbol: v

Measurement: SpeedUnit: m/s

Note: Value should be greater than 0.

Formulas to find Stream Velocity

Manning’s Roughness Coefficient

Manning’s Roughness Coefficient represents the roughness or friction applied to the flow by the channel.

Symbol: n

Measurement: NAUnit: Unitless

Note: Value can be positive or negative.

Formulas to find Manning’s Roughness Coefficient

Hydraulic Radius

Hydraulic Radius is the ratio of the cross-sectional area of a channel or pipe in which a fluid is flowing to the wet perimeter of the conduit.

Symbol: r_H

Measurement: LengthUnit: m

Note: Value can be positive or negative.

Formulas to find Hydraulic Radius

Bed Slope

Bed Slope also called channel slope is the difference in elevation between two points on a stream divided by the distance between them measured along the stream channel.

Symbol: S̄

Measurement: NAUnit: Unitless

Note: Value can be positive or negative.

Formulas to find Bed Slope

Other formulas in Manning's Equation category

Go Hydraulic radius in Manning's formula

r H = \frac{A}{P}

Go Hydraulic Radius using Manning Equation

r H = {(\frac{v \cdot n}{{S̄}^{\frac{1}{2}}})}^{\frac{3}{2}}

Go Slope of Gradient of Stream Bed given Discharge in Manning's Equation

S̄ = {(\frac{v \cdot n}{{r H}^{\frac{2}{3}}})}^{2}

How to Evaluate Manning's Equation?

Manning's Equation evaluator uses Stream Velocity = (1/Manning’s Roughness Coefficient)*(Hydraulic Radius)^(2/3)*(Bed Slope)^(1/2) to evaluate the Stream Velocity, The Manning's Equation formula is defined as the computation of the flow of water in open non-full channels and pipes without the need for a flume, weir, or other structure. Stream Velocity is denoted by v symbol.

How to evaluate Manning's Equation using this online evaluator? To use this online evaluator for Manning's Equation, enter Manning’s Roughness Coefficient (n), Hydraulic Radius (r_H) & Bed Slope (S̄) and hit the calculate button.

FAQs on Manning's Equation

What is the formula to find Manning's Equation?

The formula of Manning's Equation is expressed as Stream Velocity = (1/Manning’s Roughness Coefficient)*(Hydraulic Radius)^(2/3)*(Bed Slope)^(1/2). Here is an example- 1.848607 = (1/0.412)*(0.23)^(2/3)*(4)^(1/2).

How to calculate Manning's Equation?

With Manning’s Roughness Coefficient (n), Hydraulic Radius (r_H) & Bed Slope (S̄) we can find Manning's Equation using the formula - Stream Velocity = (1/Manning’s Roughness Coefficient)*(Hydraulic Radius)^(2/3)*(Bed Slope)^(1/2).

Can the Manning's Equation be negative?

No, the Manning's Equation, measured in Speed cannot be negative.

Which unit is used to measure Manning's Equation?

Manning's Equation is usually measured using the Meter per Second[m/s] for Speed. Meter per Minute[m/s], Meter per Hour[m/s], Kilometer per Hour[m/s] are the few other units in which Manning's Equation can be measured.

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Manning's Equation Formula

Manning's Equation Example

Manning's Equation Solution

Manning's Equation Formula Elements

Other formulas in Manning's Equation category

How to Evaluate Manning's Equation?

FAQs on Manning's Equation

Variable Name