Theis Equation To Determine Storage Coefficient Calculator

Theis Equation:

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

Transmissivity (T):

m²/s

Pumping Time (t):

seconds

Varying Dimensionless Group (u):

Distance from Pumping Well (r):

meters

Storage Coefficient (S'):

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1. What is the Theis Equation?

The Theis equation is a mathematical model used in hydrogeology to determine the storage coefficient of an aquifer. It describes the drawdown of groundwater levels in response to pumping from a well, taking into account the aquifer's transmissivity and storage properties.

2. How Does the Calculator Work?

The calculator uses the Theis equation:

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

Where:

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

Explanation: The equation calculates the storage coefficient, which represents the aquifer's ability to release groundwater from storage per unit decline in hydraulic head.

3. Importance of Storage Coefficient Calculation

Details: The storage coefficient is crucial for understanding aquifer characteristics, predicting groundwater behavior during pumping, and designing effective groundwater management strategies.

4. Using the Calculator

Tips: Enter transmissivity in m²/s, pumping time in seconds, varying dimensionless group (dimensionless), and distance from pumping well in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of storage coefficients?
A: For confined aquifers: 0.00005 to 0.005; For unconfined aquifers: 0.1 to 0.3.

Q2: How does transmissivity affect the storage coefficient?
A: Higher transmissivity generally indicates greater aquifer permeability, which can influence how quickly water is released from storage.

Q3: What is the varying dimensionless group (u)?
A: It's a dimensionless parameter used to characterize and compare physical phenomena in hydrological processes, often derived from well function calculations.

Q4: When is the Theis equation most applicable?
A: The equation is most suitable for confined aquifers with homogeneous, isotropic properties and fully penetrating wells.

Q5: What are the limitations of the Theis equation?
A: It assumes ideal aquifer conditions and may not accurately represent complex geological settings or boundary conditions.