Concept:
When water flows through a porous medium like soil, the rate of flow depends on the slope of the energy (head) line, called the hydraulic gradient.
Step 1:
The relationship states that the discharge velocity \(v\) is directly proportional to the hydraulic gradient \(i\), written as \(v = k\,i\), where \(k\) is the coefficient of permeability.
Step 2:
This fundamental law of groundwater flow was established experimentally by the French engineer Henry Darcy in 1856, and it is therefore known as Darcy's law.
Answer: Option (1) — Henry Darcy.