Confined Aquifer Discharge Given Depth Of Water In Two Wells Calculator

Formula Used:

\[ Q = \frac{2.72 \times K_w \times b_p \times (h_2 - h_1)}{\log_{10}(r_2 / r_1)} \]

Coefficient of Permeability (K_w):

m/s

Aquifer Thickness During Pumping (b_p):

Depth of Water 2 (h_2):

Depth of Water 1 (h_1):

Radial Distance at Observation Well 2 (r_2):

Radial Distance at Observation Well 1 (r_1):

Discharge (Q):

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1. What is the Confined Aquifer Discharge Formula?

The confined aquifer discharge formula calculates the rate of groundwater flow in a confined aquifer using measurements from two observation wells. This equation is based on the Thiem equation for steady-state radial flow to a well in a confined aquifer.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q = \frac{2.72 \times K_w \times b_p \times (h_2 - h_1)}{\log_{10}(r_2 / r_1)} \]

Where:

\( Q \) — Discharge (m³/s)
\( K_w \) — Coefficient of permeability (m/s)
\( b_p \) — Aquifer thickness during pumping (m)
\( h_2 \) — Depth of water in observation well 2 (m)
\( h_1 \) — Depth of water in observation well 1 (m)
\( r_2 \) — Radial distance at observation well 2 (m)
\( r_1 \) — Radial distance at observation well 1 (m)

Explanation: The formula calculates the discharge rate based on the difference in water levels between two observation wells and their distances from the pumping well.

3. Importance of Discharge Calculation

Details: Accurate discharge calculation is crucial for groundwater resource management, well design, contamination studies, and sustainable aquifer development.

4. Using the Calculator

Tips: Enter all values in the specified units. Ensure radial distances are measured from the pumping well to each observation well. All values must be positive, and r₂ cannot equal r₁.

5. Frequently Asked Questions (FAQ)

Q1: What is a confined aquifer?
A: A confined aquifer is bounded above and below by impermeable layers, with water under pressure greater than atmospheric pressure.

Q2: Why is the logarithmic function used in this formula?
A: The logarithmic function accounts for the radial flow pattern around the well, where flow velocity decreases with distance from the well.

Q3: What are typical values for coefficient of permeability?
A: Values range from 10⁻¹² m/s for clay to 10⁻² m/s for gravel. Sand typically has values between 10⁻⁵ to 10⁻³ m/s.

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

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