Correct Answer - Option 1 : laminar regime flow only

**Explanation**

Darcy's law states that there is a linear relationship between flow velocity (v) and hydraulic gradient (i) for any given saturated soil under steady laminar flow conditions.

If the rate of flow is q (volume/time) through a cross-sectional area (A) of the soil mass, Darcy's Law can be expressed as:

v = q/A = k × i

Darcy’s law is valid for fine saturated sands only.

Where

k = permeability of the soil, i = Δh/L

Δh = difference in total heads, L = length of the soil mass