Darcy's Law

Fluid Dynamics · 1856

Equation: Q = −K A (Δh / L)
Field: Fluid Dynamics
Named After: Henry Darcy
Year: 1856

Symbols

Q volume flow through a porous medium · K hydraulic conductivity, a property of the rock or soil and the fluid · A cross-section · Δh/L the drop in hydraulic head over the distance L

Significance

Groundwater moves down the head gradient at a rate set by how open the rock is. Darcy found it in 1856 sizing sand filters for the fountains of Dijon. It is the equation of a mine's dewatering cone, of how far and how fast acid drainage travels from a waste dump, of the seepage through a tailings dam, and — with a leak coefficient — of every aquifer model.

Requires

Hydrostatic Pressure Gradient

Impacts

Acid mine drainage Water table drawdown Pit lakes and perpetual treatment Arsenic mobilisation Cyanide release Tailings dam failure

Referenced by

equation

Gradient Hydrostatic Pressure

impact

Acid mine drainage Arsenic mobilisation Cyanide release Pit lakes and perpetual treatment Tailings dam failure Water table drawdown

Open on the Equations shelf — the interactive card, the filters, and everything alongside it.

From the Equations database in Notion, last edited 2026-08-18. This page is the row, rendered by the build; nothing on it is written by hand.