1. What is the Theis Equation?

The Theis equation is used to determine the transmissivity of an aquifer from pumping test data. It describes the drawdown in a confined aquifer over time due to pumping at a constant rate.

2. How Does the Calculator Work?

The calculator uses the Theis equation:

Where:

• \( T \) — Transmissivity (m²/s)
• \( Q \) — Pumping Rate (m³/s)
• \( W(u) \) — Well Function of U
• \( \pi \) — Archimedes' constant (3.141592653589793)
• \( S \) — Storage Coefficient

Explanation: The equation calculates the ability of an aquifer to transmit water throughout its entire saturated thickness.

3. Importance of Transmissivity Calculation

Details: Transmissivity is a critical parameter in groundwater hydrology that helps determine the yield of aquifers, design pumping systems, and manage groundwater resources effectively.

4. Using the Calculator

Tips: Enter pumping rate in m³/s, well function value, and storage coefficient. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of typical transmissivity values?
A: Transmissivity values typically range from 0.001 to 0.1 m²/s for most aquifers, with higher values indicating more productive aquifers.

Q2: How is the well function W(u) determined?
A: The well function is typically obtained from type-curve matching or calculated using approximation formulas based on the dimensionless parameter u.

Q3: What types of aquifers is the Theis equation applicable to?
A: The Theis equation applies to confined aquifers that are homogeneous, isotropic, infinite in extent, and have a constant thickness.

Q4: 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.

Q5: How does storage coefficient affect transmissivity calculations?
A: The storage coefficient represents the aquifer's ability to store water and directly influences the calculated transmissivity value.