State the Darcy’s law of permeability with expression. Hence define coefficient of permeability.
Darcy’s law of permeability: It states that for laminar flow, the rate of flow or discharge per unit time is directly proportional to hydraulic gradient.
Expression: q = KiA
/ = Ki
V = Ki
V/i = K
Where, q = rate of discharge
K = coefficient of permabilty
A = cross sectional area of soil sample
V = average discharge velocity
i = hydraulic gradient
Coefficient of Permeability: It is defined as the average discharge velocity of flow under a unit hydraulic gradient through a soil.
Mathematically: K = V/i