Darcy Flow Velocity Calculator

The foundational equation of groundwater flow

Darcy's Law, formulated by French engineer Henry Darcy in 1856, is the fundamental equation governing groundwater flow through porous media - it remains the basis of virtually all modern hydrogeology calculations.

Worked example

For an aquifer with 5 m/day hydraulic conductivity and a 0.02 hydraulic gradient:

v = 5 x 0.02 = 0.1 m/day

Frequently asked questions

Is this the actual speed of a water particle? No - this is Darcy velocity (specific discharge), a bulk flow rate measured over the full aquifer cross-section including solid grains. The actual average linear velocity of water moving through pore spaces is faster, found by dividing this Darcy velocity by the aquifer's porosity.

What is hydraulic conductivity used for besides this calculation? It is also a key input for contaminant transport modeling, well yield estimation, and aquifer pumping test analysis - it essentially describes how easily water moves through a given geologic material.