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Darcy's Law

Ground Water Hydrology

  1. Joseph Holden

Published Online: 15 APR 2005

DOI: 10.1002/047147844X.gw146

Water Encyclopedia

Water Encyclopedia

How to Cite

Holden, J. 2005. Darcy's Law. Water Encyclopedia. 5:63–64.

Author Information

  1. University of Leeds, Leeds, United Kingdom

Publication History

  1. Published Online: 15 APR 2005


Darcy's law is a mathematical relationship originally determined by Henry Darcy in 1856 that permits quantification of fluid flow through porous media. Many sophisticated theoretical and practical derivations have been based on Darcy's law, and it has become the foundation for quantitative groundwater flow science and soil physics. In its most useful form, the formula can be used to calculate the amount of water (or other fluid) flowing through a given cross-sectional area of a porous substance and equates volumetric discharge per unit time (q) to the product of area (A), hydraulic gradient (I = change in head per unit length) and a coefficient (K = saturated hydraulic conductivity). In its simplest terms, the relationship may be expressed as q = KIA.


  • groundwater flow;
  • soil water;
  • hydraulic conductivity;
  • laminar flow;
  • hydraulic gradient;
  • throughflow