Drawdown at Well given Radius of Influence Calculator

Formula Used:

\[ s_t = \frac{R_w}{3000 \times \sqrt{K_{dw}}} \]

Total Drawdown in Well (s_t):

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1. What is the Drawdown at Well Formula?

The drawdown at well formula calculates the total drawdown in a well based on the radius of influence and the coefficient of permeability during drawdown conditions. This is essential for understanding groundwater flow and well performance in aquifer systems.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ s_t = \frac{R_w}{3000 \times \sqrt{K_{dw}}} \]

Where:

\( s_t \) — Total Drawdown in Well (m)
\( R_w \) — Radius of Influence (m)
\( K_{dw} \) — Coefficient of Permeability at Drawdown (cm/s)

Explanation: The formula relates the drawdown at the well to the radius of influence and the soil's permeability characteristics during pumping conditions.

3. Importance of Drawdown Calculation

Details: Accurate drawdown calculation is crucial for well design, determining pumping rates, assessing aquifer characteristics, and managing groundwater resources effectively.

4. Using the Calculator

Tips: Enter the radius of influence in meters and coefficient of permeability in cm/s. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is radius of influence?
A: Radius of influence is the distance from the center of the well to the point where the drawdown curve meets the original water table level.

Q2: How is coefficient of permeability measured?
A: Coefficient of permeability is typically measured through field tests such as pumping tests or laboratory permeability tests on soil samples.

Q3: What factors affect drawdown in wells?
A: Drawdown is affected by pumping rate, aquifer characteristics, well construction, duration of pumping, and surrounding geological conditions.

Q4: When is this formula most applicable?
A: This formula is particularly useful for steady-state conditions in confined aquifers and provides a simplified approach to estimate drawdown.

Q5: Are there limitations to this equation?
A: The formula provides an approximation and may not account for all complex hydrogeological conditions, anisotropic aquifers, or transient flow conditions.