Dimensions (M, mass; L, distance; T, time) are given in brackets.
- Aaq is cross-sectional aquifer area perpendicular to the groundwater flow direction
- Asoil is cross-sectional area perpendicular to the vertical infiltration in the soil column
B is aquifer thickness [ft].
c is residual between two successive Gauss-Sedial iterations.
- C0 is liquid phase solute concentration in the infiltration water
- Caq is concentration of horizontal groundwater influx [mg/L].
- Cw is concentration of a contaminant in liquid (water) phase
- Ca is concentration of a contaminant in vapor (air) phase
- Cmx(i) is mixed concentration in groundwater
- Cs is concentration of a contaminant in solid phase [mg/Kg].
- Cs(z,0) is initial solid-phase concentration [mg/Kg].
D is combined dispersion coefficient.
- Da is gaseous phase diffusion coefficient in the pore air
- Dair is diffusion coefficient of the contaminant in the free air
- Dw is dispersion coefficient for the liquid phase contaminant in the pore water
- foc is fraction organic carbon of the soil [g/g].
- Kd is distribution coefficient between the solid phase and liquid phase
- KH is dimensional form of Henry's Law constant [atm-m3/mol].
- Koc is organic carbon-water partition coefficient [ml/g].
h is head potential [L].
H is Henry's partition coefficient between the air phase and water phase [dimensionless].
- Hd is penetration depth [ft].
- di is adjusted penetration depth for each column
- hi,j is value of the head at the lattice point at (I,j)[L].
- i is discretized soil column cell (column index in finite difference grid).
j is row index in finite difference grid.
k is time level.
K is hydraulic conductivity [L/T].
- L is horizontal length dimension of the waste [ft].
- Lu is vertical distance from the source to the observation point
(i.e., the water table) [L].
m is iteration index.
M is total contaminant mass per unit volume of the soil.
n is total porosity of the soil: equals the sum of water filled porosity and air filled porosity.
N is head to a reasonable number of points.
- qa is air flow velocity [ft/yr].
- qaq is the Darcy velocity in the aquifer [ft/yr].
- qx is specific flow rate in x direction [L/T].
- qy is specific flow rate in y direction [L/T].
- qw is water flow velocity (recharge rate) [ft/yr].
R is universal gas constant (R = 8.2�10-5 atm-m3/mol�K).
t is time [yr].
T is absolute temperature (�K = 273.16 + �C).
- t0 is duration of solute release [yr].
V is flow function.
z is vertical coordinate with positive being downward.
- aL is longitudinal dispersivity of the vadose zone
- av is transverse (vertical) dispersivity of the aquifer
- Dt is time increment.
- Dx is distance of lattice point in horizontal space
- Dy is distance of lattice point in vertical space
- g is decay rate of the solute source due to either degradation or flushing by the infiltration
- m is first order decay rate of a contaminant : in this model, for simplicity, it is assumed that
mw = ma
= ms = m.
- mw is first order decay rate of a contaminant in water phase
- ma is first order decay rate of a contaminant in gaseous phase
- ms is first order decay rate of a contaminant in solid phase
v is seepage velocity.
- q is combined retardation factor.
- qw is volumetric water content (volume of water / total volume)
- qa is air-filled porosity (volume of air / total volume)
- rb is bulk density of the soil
Last modified: Oct 15, 1999
VG Model/ Samuel Lee / VADOSE.NET