Storage Coefficient From Theis Equation Of Transmissivity Calculator

Theis Equation:

\[ S = \frac{Q \times W(u)}{T \times 4 \times \pi} \]

Storage Coefficient (S):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Theis Equation?

The Theis Equation is a fundamental equation in hydrogeology that describes the flow of groundwater to a well in a confined aquifer. It provides a mathematical model for predicting drawdown in an aquifer over time due to pumping.

2. How Does the Calculator Work?

The calculator uses the Theis Equation:

\[ S = \frac{Q \times W(u)}{T \times 4 \times \pi} \]

Where:

\( S \) — Storage Coefficient (dimensionless)
\( Q \) — Pumping Rate (m³/s)
\( W(u) \) — Well Function of U (dimensionless)
\( T \) — Transmissivity (m²/s)
\( \pi \) — Mathematical constant pi (approximately 3.1416)

Explanation: The equation calculates the storage coefficient, which represents the volume of water released from storage per unit decline in hydraulic head in the aquifer, per unit area of the aquifer.

3. Importance of Storage Coefficient Calculation

Details: The storage coefficient is a crucial parameter in groundwater hydrology as it helps in understanding the aquifer's response to pumping, predicting drawdown, and managing groundwater resources effectively.

4. Using the Calculator

Tips: Enter pumping rate in m³/s, well function of U (dimensionless), and transmissivity in m²/s. All values must be positive and valid.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range of storage coefficient values?
A: For confined aquifers, storage coefficients typically range from 0.00005 to 0.005. For unconfined aquifers, specific yield values range from 0.01 to 0.3.

Q2: How is the well function W(u) determined?
A: W(u) is typically determined from type curves or calculated using mathematical approximations based on the value of u, which is a function of time, distance, transmissivity, and storage coefficient.

Q3: What factors affect the storage coefficient?
A: The storage coefficient depends on aquifer compressibility, water compressibility, and aquifer thickness. It represents the aquifer's ability to store and release water.

Q4: When is the Theis equation applicable?
A: The Theis equation applies to confined aquifers that are homogeneous, isotropic, infinite in extent, and have fully penetrating wells with constant pumping rates.

Q5: What are the limitations of the Theis equation?
A: The equation assumes ideal conditions and may not accurately represent aquifers with boundaries, heterogeneity, or unconfined conditions where water table effects are significant.