Darcy's Law
A foundational hydrogeological equation describing the flow rate of fluid through a porous medium under a hydraulic gradient.
Governing formula
Q = -K A (dh / dl), q = Q / A = -K ∇h
SI unit
m/s (Darcy Flux q)
In depth
Formulated by Henry Darcy in 1856. States that discharge rate Q is directly proportional to hydraulic conductivity K, cross-sectional area A, and hydraulic head gradient (dh/dl).
Examples in the real world
Calculating groundwater flow rates through sand aquifers and estimating water extraction from wells.