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. It's 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:

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)
• \( Initial\ Aquifer\ Thickness \) — Aquifer thickness at initial stage before pumping (Meter)
• \( Depth\ of\ Water \) — Water depth in the well measured above the impermeable layer (Meter)
• \( Discharge\ at\ Time\ t=0 \) — Initial rate of flow from the well (Cubic Meter per Second)
• \( \pi \) — Archimedes' constant (approximately 3.14159)
• \( \exp \) — Exponential function

Explanation: The equation calculates how far the influence of pumping extends into the aquifer based on the well characteristics and aquifer properties.

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.

4. Using the Calculator

Tips: Enter all values in appropriate units. Ensure that Initial Aquifer Thickness is greater than Depth of Water, and all values are positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the practical significance of radius of influence?
A: It helps determine how far pumping from a well will affect the water table and whether nearby wells might interfere with each other.

Q2: How does coefficient of transmissibility affect the radius?
A: Higher transmissibility coefficients result in larger radii of influence, as water can move more easily through the aquifer.

Q3: What factors can cause the actual radius to differ from calculated?
A: Heterogeneous aquifer properties, boundary conditions, and time-dependent effects can cause differences between calculated and actual radii.

Q4: Is this formula applicable to all aquifer types?
A: This formula is primarily used for confined aquifers. Different equations may be needed for unconfined aquifers or other specific conditions.

Q5: How does pumping rate affect the radius of influence?
A: Higher pumping rates generally increase the radius of influence, as more water is being extracted from a larger area of the aquifer.