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W-Index Formula

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W-Index is the average infiltration rate during the time when the rainfall intensity exceeds the infiltration rate. Check FAQs

W = \frac{P - R - I a}{t e}

W - W-Index?P - Total Storm Precipitation?R - Total Storm Runoff?I_a - Depression and Interception Losses?t_e - Duration of Rainfall Excess?

W-Index Example

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With units

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Here is how the W-Index equation looks like with Values.

Here is how the W-Index equation looks like with Units.

Here is how the W-Index equation looks like.

16 = \frac{118 - 48 - 6}{4}

16cm = \frac{118cm - 48cm - 6cm}{4h}

16 = \frac{118 - 48 - 6}{4}

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W-Index Solution

Follow our step by step solution on how to calculate W-Index?

FIRST Step Consider the formula

W = \frac{P - R - I a}{t e}

Next Step Substitute values of Variables

∴

W = \frac{118cm - 48cm - 6cm}{4h}

Next Step Prepare to Evaluate

∴

W = \frac{118 - 48 - 6}{4}

Next Step Evaluate

∴

W = 0.16m

LAST Step Convert to Output's Unit

∴

W = 16cm

W-Index Formula Elements

Variables

W-Index

W-Index is the average infiltration rate during the time when the rainfall intensity exceeds the infiltration rate.

Symbol: W

Measurement: LengthUnit: cm

Note: Value should be greater than 0.

Formulas to find W-Index

Total Storm Precipitation

Total Storm Precipitation is the annual precipitation of the current year.

Symbol: P

Measurement: LengthUnit: cm

Note: Value should be greater than 0.

Formulas to find Total Storm Precipitation

Total Storm Runoff

Total Storm Runoff is rain that flows off building rooftops, driveways, lawns, streets, parking lots, construction sites, and industrial storage yards.

Symbol: R

Measurement: LengthUnit: cm

Note: Value should be greater than 0.

Formulas to find Total Storm Runoff

Depression and Interception Losses

Depression and Interception Losses is the portion of the precipitation that is returned to the atmosphere through evaporation from plant surfaces .

Symbol: I_a

Measurement: LengthUnit: cm

Note: Value can be positive or negative.

Formulas to find Depression and Interception Losses

Duration of Rainfall Excess

Duration of Rainfall Excess is the total time in which the rainfall intensity the greater than the average rate of infiltration (in hours).

Symbol: t_e

Measurement: TimeUnit: h

Note: Value should be greater than 0.

Formulas to find Duration of Rainfall Excess

Other formulas in W Index category

Go Total Storm Precipitation when W Index

P = (W \cdot t e) + R + I a

Go Total Storm Runoff given W Index

R = P - I a - (W \cdot t e)

Go Initial Losses given W-Index

I a = P - R - (W \cdot t e)

Go Duration of Rainfall Excess given W Index

t e = \frac{P - R - I a}{W}

How to Evaluate W-Index?

W-Index evaluator uses W-Index = (Total Storm Precipitation-Total Storm Runoff-Depression and Interception Losses)/Duration of Rainfall Excess to evaluate the W-Index, The W-Index formula is defined as the average infiltration rate during the time when the rainfall intensity exceeds the infiltration rate. W-Index is denoted by W symbol.

How to evaluate W-Index using this online evaluator? To use this online evaluator for W-Index, enter Total Storm Precipitation (P), Total Storm Runoff (R), Depression and Interception Losses (I_a) & Duration of Rainfall Excess (t_e) and hit the calculate button.

FAQs on W-Index

What is the formula to find W-Index?

The formula of W-Index is expressed as W-Index = (Total Storm Precipitation-Total Storm Runoff-Depression and Interception Losses)/Duration of Rainfall Excess. Here is an example- 1600 = (1.18-0.48-0.06)/14400.

How to calculate W-Index?

With Total Storm Precipitation (P), Total Storm Runoff (R), Depression and Interception Losses (I_a) & Duration of Rainfall Excess (t_e) we can find W-Index using the formula - W-Index = (Total Storm Precipitation-Total Storm Runoff-Depression and Interception Losses)/Duration of Rainfall Excess.

Can the W-Index be negative?

No, the W-Index, measured in Length cannot be negative.

Which unit is used to measure W-Index?

W-Index is usually measured using the Centimeter[cm] for Length. Meter[cm], Millimeter[cm], Kilometer[cm] are the few other units in which W-Index can be measured.

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W-Index Formula

W-Index Example

W-Index Solution

W-Index Formula Elements

Other formulas in W Index category

How to Evaluate W-Index?

FAQs on W-Index

Variable Name