Correct Answer - Option 1 : laminar regime flow only
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.
k = permeability of the soil, i = Δh/L
Δh = difference in total heads, L = length of the soil mass