1. What is Hydraulic Gradient?

The hydraulic gradient (i) is the change in hydraulic head per unit distance of flow in a given direction. It represents the driving force for groundwater flow and is a fundamental concept in hydrogeology.

2. How Does the Calculator Work?

The calculator uses the hydraulic gradient equation:

Where:

• \( i \) — Hydraulic gradient (dimensionless)
• \( h_1 \) — Hydraulic head at point 1 (m)
• \( h_2 \) — Hydraulic head at point 2 (m)
• \( L \) — Distance between measurement points (m)

Explanation: The equation calculates the slope of the hydraulic head, which determines the direction and rate of groundwater flow.

3. Importance of Hydraulic Gradient

Details: Hydraulic gradient is crucial for understanding groundwater flow direction, calculating flow rates (using Darcy's Law), and assessing contaminant transport in aquifers.

4. Using the Calculator

Tips: Enter hydraulic head values in meters (typically from well measurements), and the horizontal distance between measurement points. All values must be positive, with distance > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical hydraulic gradient value?
A: In natural systems, gradients typically range from 0.001 to 0.01, but can be higher near pumping wells or in steep terrains.

Q2: How does hydraulic gradient relate to flow velocity?
A: According to Darcy's Law, flow velocity is proportional to hydraulic gradient (v = Ki, where K is hydraulic conductivity).

Q3: Can the gradient be negative?
A: Yes, a negative gradient simply means flow is in the opposite direction of what was assumed in the calculation.

Q4: How accurate are field measurements?
A: Accuracy depends on precise water level measurements and proper surveying of well elevations and locations.

Q5: Does this apply to confined and unconfined aquifers?
A: Yes, though head measurements differ slightly between confined (pressure head) and unconfined (water table elevation) aquifers.