Top Posts
You are here: Home » Engineering » Soil Mechanics » Darcy’s Law of Permeability

Darcy’s Law of Permeability

Darcy’s Law of Permeability

The law of flow of water through soil was first studied by Darcy (1856)  who demonstrated experimentally that for laminer flow conditions in a saturated soil, the rate of flow or the discharge per unit lime is proportional to the hydraulic gradient.

    q  =   k i A

V = q / A = k i


q = discharge per unit time
A = total cross-sectional area of soil mass, perpendicular to the direction of flow
i  = hydraulic gradient
k =  Darcy’ s coefficient of permeability
v = velocity of flow, or average discharge velocity.

Flow of Water Through Soil

Flow of Water Through Soil (Permeability)

If a soil sample of length L and cross-sectional area A, is subjected to differential head of water  h1 – h2 ,the hydraulic gradient i will be equal to h1 – h2 / L and, we have

q = k (h1 – h2 / L) A

From Equation when hydraulic gradient is unity, k is equal to v. Thus, the coefficient of permeability, or simply Permeability  is defined as the average velocity of flow that will occur through the total cross-sectional area of soil under unit hydraulic gradient. The dimensions of the coefficient of permeability k  are the same as those of velocity. It is usually as cm/sec  or m/day or feet/day.

About Mustafa

My name is Mustafa Awais, I am basically from Pakistan & Currently living in Saudia Arabia, I am Civil Engineer as well as Web Master.

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Scroll To Top