#
Equations of Hydrogeology

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Darcy's Law (linear flow):

q is flux (flow/area)

K is hydraulic conductivity

H is total head (hydraulic head + pressure head)

q is water content

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Richard equation (unsaturated flow):

h is hydraulic or pressure head

z is gravity head (elevation)

D is soil diffusivity (
)

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Fick's law (mass transport by diffusion):

First Law

J is the solute flux

D is the molecular diffusion coefficient

c is concentration of the solute (solute/unit mass of liquid)

Second Law