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Aquifer Constant Given Modified Drawdown Calculator

Aquifer Constant Formula:

\[ T = \frac{Q \cdot \ln\left(\frac{r_2}{r_1}\right)}{2.72 \cdot (s_1' - s_2')} \]

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1. What is Aquifer Constant?

The Aquifer Constant, also known as coefficient of transmissibility, represents the rate at which water is transmitted through a unit width of an aquifer under a unit hydraulic gradient. It is a key parameter in groundwater hydrology.

2. How Does the Calculator Work?

The calculator uses the aquifer constant formula:

\[ T = \frac{Q \cdot \ln\left(\frac{r_2}{r_1}\right)}{2.72 \cdot (s_1' - s_2')} \]

Where:

Explanation: The formula calculates the transmissivity of an aquifer based on discharge rates and drawdown measurements from observation wells.

3. Importance of Aquifer Constant Calculation

Details: Accurate calculation of aquifer constant is crucial for groundwater resource management, well design, contaminant transport studies, and sustainable water extraction planning.

4. Using the Calculator

Tips: Enter discharge in m³/s, radial distances in meters, and modified drawdown values in meters. Ensure all values are positive and the drawdown difference is not zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between aquifer constant and hydraulic conductivity?
A: Aquifer constant (transmissivity) is the product of hydraulic conductivity and aquifer thickness, representing the overall transmission capacity of the aquifer.

Q2: What are typical values for aquifer constant?
A: Values range from 0.1 m²/day for clay aquifers to over 1000 m²/day for highly productive sand and gravel aquifers.

Q3: When should this calculation be used?
A: This calculation is used in pumping tests to determine the transmissivity of confined aquifers using data from observation wells.

Q4: Are there limitations to this equation?
A: This equation assumes ideal conditions: homogeneous isotropic aquifer, fully penetrating well, and steady-state flow conditions.

Q5: What is modified drawdown?
A: Modified drawdown accounts for well loss and other factors that may affect the actual drawdown measurement in observation wells.

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