Coefficient Of Permeability Given Discharge In Unconfined Aquifer Calculator

Formula Used:

\[ KWH = \frac{Q}{\frac{\pi (H^2 - hw^2)}{\ln\left(\frac{Rw}{r}\right)}} \]

Discharge (Q):

m³/s

Thickness of Unconfined Aquifer (H):

Depth of Water (hw):

Radius of Influence (Rw):

Radius of Well (r):

Coefficient of Permeability (KWH):

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1. What is Coefficient of Permeability in Well Hydraulics?

The Coefficient of Permeability in Well Hydraulics describes how easily a liquid will move through the soil. It is a crucial parameter in groundwater studies and well design, indicating the soil's ability to transmit water.

2. How Does the Calculator Work?

The calculator uses the formula for unconfined aquifers:

\[ KWH = \frac{Q}{\frac{\pi (H^2 - hw^2)}{\ln\left(\frac{Rw}{r}\right)}} \]

Where:

\( KWH \) — Coefficient of Permeability (m/s)
\( Q \) — Discharge rate (m³/s)
\( H \) — Thickness of unconfined aquifer (m)
\( hw \) — Depth of water in the well (m)
\( Rw \) — Radius of influence (m)
\( r \) — Radius of well (m)
\( \pi \) — Mathematical constant pi (≈3.1416)
\( \ln \) — Natural logarithm function

Explanation: This formula calculates the soil's permeability based on the well's discharge characteristics and geometric parameters.

3. Importance of Permeability Calculation

Details: Accurate permeability estimation is essential for groundwater resource assessment, well yield prediction, contaminant transport studies, and designing effective dewatering systems.

4. Using the Calculator

Tips: Enter all values in consistent units (meters and m³/s). Ensure that radius of influence is greater than well radius, and water depth is less than aquifer thickness for valid results.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between confined and unconfined aquifers?
A: Unconfined aquifers have a water table that serves as the upper boundary, while confined aquifers are bounded above and below by impermeable layers.

Q2: How does permeability affect well performance?
A: Higher permeability allows greater water flow into the well, resulting in higher sustainable yields and smaller drawdowns.

Q3: What are typical permeability values for different soils?
A: Clay: 10⁻⁸-10⁻¹⁰ m/s, Sand: 10⁻³-10⁻⁵ m/s, Gravel: 10⁻¹-10⁻³ m/s. Actual values vary based on soil composition.

Q4: When is this formula applicable?
A: This formula applies to steady-state flow in unconfined aquifers with fully penetrating wells and homogeneous, isotropic soil conditions.

Q5: What are the limitations of this calculation?
A: The formula assumes ideal conditions and may not account for aquifer heterogeneity, partial penetration, or transient flow conditions.