Radius Of Influence Given Drawdown At Well Calculator

Radius of Influence Formula:

\[ Radius\ of\ Influence = Radius\ of\ well \times \exp\left(\frac{2\pi \times Coefficient\ of\ Transmissibility \times Total\ Drawdown\ in\ Well}{Discharge\ of\ Liquid}\right) \]

Radius of Well (r):

Meter

Coefficient of Transmissibility (Tenvi):

Square Meter per Second

Total Drawdown in Well (st):

Meter

Discharge of Liquid (Qli):

Cubic Meter per Second

Radius of Influence (Rw):

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1. What is the Radius of Influence Formula?

The Radius of Influence formula calculates the distance from the center of a well to the point where the drawdown curve meets the original water table. This is an important parameter in hydrogeology for determining the area affected by pumping from a well.

2. How Does the Calculator Work?

The calculator uses the Radius of Influence equation:

\[ Radius\ of\ Influence = Radius\ of\ well \times \exp\left(\frac{2\pi \times Coefficient\ of\ Transmissibility \times Total\ Drawdown\ in\ Well}{Discharge\ of\ Liquid}\right) \]

Where:

\( Radius\ of\ well \) — Distance from center of well to its outer boundary (Meter)
\( Coefficient\ of\ Transmissibility \) — Rate of flow of water through a vertical strip of the aquifer (Square Meter per Second)
\( Total\ Drawdown\ in\ Well \) — Reduction in hydraulic head observed at a well (Meter)
\( Discharge\ of\ Liquid \) — Rate of flow of liquid (Cubic Meter per Second)
\( \pi \) — Archimedes' constant (approximately 3.1416)
\( \exp \) — Exponential function

Explanation: The equation calculates the extent of the cone of depression around a pumping well, which represents the area where groundwater levels are affected by the pumping.

3. Importance of Radius of Influence Calculation

Details: Calculating the radius of influence is crucial for well field design, determining well spacing, assessing interference between wells, and managing groundwater resources effectively. It helps in understanding the extent of environmental impact from pumping activities.

4. Using the Calculator

Tips: Enter all values in appropriate units (meters for distance, square meters per second for transmissibility, and cubic meters per second for discharge). All values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What factors affect the radius of influence?
A: The radius of influence is affected by aquifer properties (transmissibility, storage coefficient), pumping rate, duration of pumping, and well characteristics.

Q2: How does pumping rate affect the radius of influence?
A: Higher pumping rates generally result in a larger radius of influence, as more water is being extracted from a larger area of the aquifer.

Q3: What is the difference between radius of influence and radius of investigation?
A: Radius of influence refers to the area affected by pumping, while radius of investigation refers to the distance from which information can be obtained during a pumping test.

Q4: Can the radius of influence change over time?
A: Yes, the radius of influence typically increases with the duration of pumping until it stabilizes when equilibrium conditions are reached.

Q5: How accurate is this formula for real-world applications?
A: While this formula provides a good estimate, real-world conditions may vary due to aquifer heterogeneity, boundary conditions, and other factors. Field measurements are recommended for precise applications.