Coefficient Of Transmissibility Given Confined Aquifer Discharge Calculator

Formula Used:

\[ \text{Coefficient of Transmissibility} = \frac{\text{Discharge}}{\frac{2\pi \times \text{Total Drawdown in Well}}{\log_e\left(\frac{\text{Radius of Influence}}{\text{Radius of well}}\right)}} \]

Discharge (Q):

m³/s

Total Drawdown in Well (st):

Radius of Influence (Rw):

Radius of well (r):

Coefficient of Transmissibility:

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1. What is the Coefficient of Transmissibility?

The Coefficient of Transmissibility is defined as the rate of flow of water in gallons per day through a vertical strip of the aquifer. It represents the ability of an aquifer to transmit water throughout its entire saturated thickness.

2. How Does the Calculator Work?

The calculator uses the following formula:

\[ \text{Coefficient of Transmissibility} = \frac{Q}{\frac{2\pi \times st}{\log_e\left(\frac{Rw}{r}\right)}} \]

Where:

\( Q \) — Discharge (m³/s)
\( \pi \) — Archimedes' constant (3.141592653589793)
\( st \) — Total Drawdown in Well (m)
\( \log_e \) — Natural logarithm function
\( Rw \) — Radius of Influence (m)
\( r \) — Radius of well (m)
\( e \) — Napier's constant (2.718281828459045)

Explanation: This formula calculates the transmissibility coefficient for confined aquifers based on pumping test data, incorporating the natural logarithm of the ratio between radius of influence and well radius.

3. Importance of Coefficient of Transmissibility

Details: The coefficient of transmissibility is crucial for groundwater resource assessment, well design, and predicting the behavior of aquifers under pumping conditions. It helps in determining the sustainable yield of wells and managing groundwater resources effectively.

4. Using the Calculator

Tips: Enter discharge in m³/s, total drawdown in meters, radius of influence in meters, and radius of well in meters. All values must be positive, and the radius of influence must be greater than the radius of the well for valid results.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between transmissibility and permeability?
A: Transmissibility refers to the ability of the entire aquifer thickness to transmit water, while permeability refers to the ability of the aquifer material itself to transmit fluids.

Q2: What are typical values for coefficient of transmissibility?
A: Values can range from less than 100 m²/day for poor aquifers to over 10,000 m²/day for highly productive aquifers, depending on the geological formation.

Q3: When is this formula applicable?
A: This formula is specifically designed for confined aquifers where the aquifer is bounded above and below by impermeable layers.

Q4: What are the limitations of this calculation?
A: The calculation assumes ideal conditions, homogeneous aquifer properties, and steady-state flow. Real-world conditions with heterogeneous aquifers may require more complex analysis.

Q5: How does well construction affect the results?
A: Proper well construction is essential for accurate measurements. Well screen length, placement, and development can significantly impact the calculated transmissibility values.