Discharge In Confined Aquifer Calculator

Formula Used:

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

Coefficient of Permeability (KWH):

m/s

Aquifer Thickness (bw):

Initial Aquifer Thickness (Hi):

Depth of Water (hw):

Radius of Influence (Rw):

Radius of Well (r):

Discharge (Q):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Discharge in Confined Aquifer Formula?

The discharge formula for confined aquifers calculates the rate of groundwater flow using the Thiem equation. It determines the discharge rate based on aquifer properties and well characteristics in a confined aquifer system.

2. How Does the Calculator Work?

The calculator uses the confined aquifer discharge formula:

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

Where:

\( Q \) — Discharge rate (m³/s)
\( KWH \) — Coefficient of permeability (m/s)
\( bw \) — Aquifer thickness (m)
\( Hi \) — Initial aquifer thickness (m)
\( hw \) — Depth of water (m)
\( Rw \) — Radius of influence (m)
\( r \) — Radius of well (m)
\( \pi \) — Mathematical constant pi (≈3.1416)
\( \ln \) — Natural logarithm function

Explanation: The formula calculates groundwater discharge based on the hydraulic properties of the confined aquifer and well geometry.

3. Importance of Discharge Calculation

Details: Accurate discharge calculation is crucial for groundwater resource management, well design, pumping test analysis, and sustainable water extraction planning in confined aquifer systems.

4. Using the Calculator

Tips: Enter all values in consistent units (meters and meters/second). Ensure all input values are positive and Radius of Influence is greater than Radius of Well for valid calculations.

5. Frequently Asked Questions (FAQ)

Q1: What is a confined aquifer?
A: A confined aquifer is an aquifer bounded above and below by impermeable layers, creating artesian conditions where water is under pressure.

Q2: How does this differ from unconfined aquifer discharge?
A: Confined aquifer formulas account for constant aquifer thickness, while unconfined aquifer formulas consider the water table drawdown cone.

Q3: What are typical values for coefficient of permeability?
A: Permeability values range from 10⁻² m/s for gravel to 10⁻⁹ m/s for clay, with sand typically around 10⁻⁴ to 10⁻⁵ m/s.

Q4: How is radius of influence determined?
A: Radius of influence is typically determined through pumping tests and can range from tens to hundreds of meters depending on aquifer properties.

Q5: What are the limitations of this formula?
A: This formula assumes steady-state flow, homogeneous isotropic aquifer, fully penetrating well, and negligible well losses.