Darcy's Law

Q = -KA\frac{dh}{dl}

Groundwater flow rate proportional to hydraulic conductivity and pressure gradient.

By Henry Darcy

Earth System Sciences

Darcy's Law

1856 · Henry Darcy

Why it matters: Foundation of hydrogeology, petroleum engineering, and soil mechanics.

Discoverers: Henry Darcy (1856)

What does it mean?

Groundwater flow rate proportional to hydraulic conductivity and pressure gradient.

Foundation of hydrogeology, petroleum engineering, and soil mechanics.

Symbol	Name	Unit	Meaning
$Q$	Discharge	m³/s	Volumetric flow rate
$K$	Conductivity	m/s	Hydraulic conductivity
$A$	Area	m²	Cross-sectional area
$dh/dl$	Gradient	—	Hydraulic gradient

Higher K sandstone aquifers transmit more water per gradient.

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Q = -KA\frac{dh}{dl}

Real-world impact

Precision agriculture

Equations optimize food production for billions.

Photo: Unsplash — precision farming

Groundwater flow rate proportional to hydraulic conductivity and pressure gradient.

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