Distance From Pumping Well To Observation Well Calculator

Formula Used:

\[ r = \sqrt{\frac{2.25 \times \tau \times t_o}{S}} \]

Distance from Pumping Well (r):

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1. What is the Distance Calculation Formula?

The formula calculates the distance from a pumping well to an observation well based on aquifer properties and time measurements. It's derived from the Theis equation and is used in hydrogeological studies to determine well interference and aquifer characteristics.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ r = \sqrt{\frac{2.25 \times \tau \times t_o}{S}} \]

Where:

\( r \) — Distance from pumping well to observation well (meters)
\( \tau \) — Transmissivity (m²/s)
\( t_o \) — Time at the point of intersection (minutes)
\( S \) — Storage coefficient (dimensionless)

Explanation: The formula calculates the radial distance where the drawdown curve intersects the zero-drawdown line on a time-drawdown graph.

3. Importance of Distance Calculation

Details: Accurate distance calculation is crucial for determining well spacing, assessing aquifer properties, and predicting interference between pumping wells in groundwater management.

4. Using the Calculator

Tips: Enter transmissivity in m²/s, time in minutes, and storage coefficient (dimensionless). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is transmissivity?
A: Transmissivity is the rate at which water flows through a unit width of an aquifer under a unit hydraulic gradient, measured in m²/s.

Q2: What does the storage coefficient represent?
A: The storage coefficient represents the volume of water released from storage per unit decline in hydraulic head per unit area of the aquifer.

Q3: When is this formula typically used?
A: This formula is used in pumping test analysis to determine the distance where the drawdown becomes negligible or to calculate aquifer properties from time-drawdown data.

Q4: What are typical ranges for these parameters?
A: Transmissivity typically ranges from 10⁻⁵ to 10⁻¹ m²/s, storage coefficient from 10⁻⁵ to 10⁻³ for confined aquifers, and time values can range from minutes to days.

Q5: Are there limitations to this calculation?
A: This calculation assumes homogeneous, isotropic aquifer conditions and may not be accurate for complex geological settings or when boundary conditions affect the flow.