Transmissivity Given Storage Coefficient From Theis Equation Calculator

Theis Equation:

\[ T = \frac{S' \times r^2}{4 \times t \times u} \]

Storage Coefficient (S'):

(dimensionless)

Distance from Pumping Well (r):

meters

Pumping Time (t):

seconds

Varying Dimensionless Group (u):

(dimensionless)

Transmissivity (T):

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1. What is the Theis Equation?

The Theis equation is a mathematical model used in hydrogeology to analyze the drawdown of groundwater levels in response to pumping from a well. It provides a solution for transient flow to a well in a confined aquifer.

2. How Does the Calculator Work?

The calculator uses the Theis equation:

\[ T = \frac{S' \times r^2}{4 \times t \times u} \]

Where:

\( T \) — Transmissivity (m²/s)
\( S' \) — Storage Coefficient (dimensionless)
\( r \) — Distance from Pumping Well (meters)
\( t \) — Pumping Time (seconds)
\( u \) — Varying Dimensionless Group (dimensionless)

Explanation: The equation calculates the transmissivity of an aquifer based on the storage coefficient, distance from the pumping well, pumping time, and a dimensionless parameter group.

3. Importance of Transmissivity Calculation

Details: Transmissivity is a critical parameter in groundwater hydrology that quantifies the ability of an aquifer to transmit water. It is essential for well design, groundwater management, and contamination studies.

4. Using the Calculator

Tips: Enter all values with appropriate units. Storage coefficient and dimensionless group are dimensionless parameters. Distance should be in meters, and pumping time in seconds. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is transmissivity in groundwater hydrology?
A: Transmissivity is the rate at which groundwater flows horizontally through an aquifer. It represents the product of hydraulic conductivity and aquifer thickness.

Q2: What is the storage coefficient?
A: The storage coefficient is a dimensionless parameter that describes the ability of an aquifer to release groundwater from storage per unit decline in hydraulic head.

Q3: What does the varying dimensionless group represent?
A: The varying dimensionless group is a parameter used to characterize and compare physical phenomena in hydrological processes, often related to well function in aquifer testing.

Q4: What are typical values for transmissivity?
A: Transmissivity values vary widely depending on aquifer type, ranging from less than 1 m²/day for clay aquitards to over 1000 m²/day for highly productive sand and gravel aquifers.

Q5: When is the Theis equation applicable?
A: The Theis equation applies to confined aquifers with homogeneous, isotropic properties, infinite areal extent, and fully penetrating wells with constant discharge rates.