Well Function Given Drawdown Calculator

Well Function of u Formula:

\[ Wu = \frac{4 \times \pi \times FT \times st}{Q} \]

Formation Constant T given Change in Drawdown (FT):

m²/s

Total Drawdown in Well (st):

Discharge (Q):

m³/s

Well Function of u (Wu):

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1. What is Well Function of u?

Well Function of u is the data plot of drawdown versus time (or drawdown versus t/rz) is matched to the type curve of W(u) versus 1/u. It is a fundamental concept in groundwater hydrology used to analyze aquifer test data.

2. How Does the Calculator Work?

The calculator uses the Well Function of u formula:

\[ Wu = \frac{4 \times \pi \times FT \times st}{Q} \]

Where:

\( \pi \) — Archimedes' constant (3.141592653589793)
\( FT \) — Formation Constant T given Change in Drawdown (m²/s)
\( st \) — Total Drawdown in Well (m)
\( Q \) — Discharge (m³/s)

Explanation: The equation calculates the well function value based on formation constant, total drawdown, and discharge rate.

3. Importance of Well Function Calculation

Details: Accurate calculation of well function is crucial for analyzing aquifer test data, determining aquifer properties, and predicting groundwater flow behavior in unsteady flow conditions.

4. Using the Calculator

Tips: Enter Formation Constant T in m²/s, Total Drawdown in meters, and Discharge in m³/s. All values must be positive and greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of Well Function of u?
A: The Well Function of u represents the theoretical drawdown in a confined aquifer due to pumping at a constant rate from a well.

Q2: When is this calculation typically used?
A: This calculation is used in aquifer performance tests to determine transmissivity and storage coefficient of confined aquifers.

Q3: What are typical ranges for the input parameters?
A: Formation constants typically range from 0.001-100 m²/s, drawdown from 0.1-10 meters, and discharge rates from 0.01-10 m³/s depending on the aquifer characteristics.

Q4: Are there limitations to this equation?
A: The equation assumes ideal conditions including homogeneous isotropic aquifer, fully penetrating well, and negligible well storage effects.

Q5: How accurate is this calculation for real-world applications?
A: While based on theoretical models, this calculation provides good approximations for many practical groundwater applications when proper field measurements are taken.