Drawdown In Aquifer Caused By Pumping At Any Point In Aquifer Calculator

Formula Used:

\[ s' = \frac{q \times t}{\tau \times S \times r^2} \]

Pumping Rate (q):

m³/s

Time Period (t):

seconds

Transmissivity (τ):

m²/s

Storage Coefficient (S):

Distance from Pumping Well (r):

meters

Possible Drawdown in Confined Aquifer (s'):

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1. What is the Drawdown in Aquifer Formula?

The drawdown in aquifer formula calculates the possible drawdown in a confined aquifer caused by pumping at any point. It represents the drawdown that would have occurred if the aquifer had been confined (that is, if no dewatering had occurred).

2. How Does the Calculator Work?

The calculator uses the formula:

\[ s' = \frac{q \times t}{\tau \times S \times r^2} \]

Where:

\( s' \) — Possible Drawdown in Confined Aquifer (meters)
\( q \) — Pumping Rate (m³/s)
\( t \) — Time Period (seconds)
\( \tau \) — Transmissivity (m²/s)
\( S \) — Storage Coefficient
\( r \) — Distance from Pumping Well (meters)

Explanation: The formula calculates the drawdown based on pumping rate, time period, aquifer properties, and distance from the pumping well.

3. Importance of Drawdown Calculation

Details: Accurate drawdown estimation is crucial for groundwater management, well design, and predicting the impact of pumping on aquifer systems.

4. Using the Calculator

Tips: Enter all values with appropriate units. Pumping rate in m³/s, time in seconds, transmissivity in m²/s, storage coefficient (dimensionless), and distance in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is a confined aquifer?
A: A confined aquifer is an aquifer below the land surface that is saturated with water and bounded above and below by layers of impermeable material.

Q2: How does transmissivity affect drawdown?
A: Higher transmissivity values result in lower drawdown for the same pumping rate, as water can move more easily through the aquifer.

Q3: What is the storage coefficient?
A: The storage coefficient is the volume of water released from storage per unit decline in hydraulic head in the aquifer, per unit area of the aquifer.

Q4: Why does distance from the pumping well matter?
A: Drawdown decreases with increasing distance from the pumping well due to the spreading of the cone of depression.

Q5: What are typical values for storage coefficient?
A: For confined aquifers, storage coefficients typically range from 0.00005 to 0.005, while for unconfined aquifers, they range from 0.05 to 0.30.