q is flux (flow/area)
K is hydraulic conductivity
H is total head (hydraulic head + pressure head)
q is water content
h is hydraulic or pressure head
z is gravity head (elevation)
D is soil diffusivity ( )
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
y is capillary pressure head
M=1-1/N