W-Index Given Duration Of Rainfall Calculator

W-Index Formula:

\[ W = \frac{(P_{cm} - R)}{t_r} \]

W-Index:

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1. What is W-Index?

W-Index refers to the uniform rate of infiltration during a rainstorm after initial infiltration capacity has decreased, typically measured in cm/s. It represents the steady infiltration rate that occurs after the initial high infiltration capacity has diminished.

2. How Does the Calculator Work?

The calculator uses the W-Index formula:

\[ W = \frac{(P_{cm} - R)}{t_r} \]

Where:

\( W \) — W-Index (cm/s)
\( P_{cm} \) — Rainfall Depth (cm)
\( R \) — Runoff Depth (cm)
\( t_r \) — Rainfall Duration (seconds)

Explanation: The formula calculates the uniform infiltration rate by subtracting runoff depth from rainfall depth and dividing by the rainfall duration.

3. Importance of W-Index Calculation

Details: W-Index is crucial for hydrological modeling, flood prediction, irrigation planning, and understanding soil infiltration characteristics. It helps in designing drainage systems and managing water resources effectively.

4. Using the Calculator

Tips: Enter rainfall depth and runoff depth in centimeters, rainfall duration in seconds. All values must be positive numbers with rainfall depth greater than or equal to runoff depth.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of W-Index values?
A: W-Index values typically range from 0.001 to 0.1 cm/s, depending on soil type, vegetation cover, and initial moisture conditions.

Q2: How does W-Index differ from initial infiltration rate?
A: W-Index represents the steady infiltration rate after the initial high infiltration capacity has decreased, while initial infiltration rate is the maximum rate at the start of rainfall.

Q3: What factors affect W-Index values?
A: Soil texture, compaction, vegetation cover, antecedent moisture content, and land use practices significantly influence W-Index values.

Q4: When is W-Index measurement most accurate?
A: W-Index is most accurate for moderate intensity rainfall events where uniform infiltration conditions are established.

Q5: Can W-Index be used for all soil types?
A: While applicable to most soil types, W-Index may need adjustment for extremely sandy or clayey soils where infiltration characteristics differ significantly.