Dimensions (M, mass; L, distance; T, time) are given in brackets. 

  1. Aaq is cross-sectional aquifer area perpendicular to the groundwater flow direction [L2]. 
  2. Asoil is cross-sectional area perpendicular to the vertical infiltration in the soil column [L2]. 
  3. B is aquifer thickness [ft]. 
  4. c is residual between two successive Gauss-Sedial iterations. 
  5. C0 is liquid phase solute concentration in the infiltration water [mg/L]. 
  6. Caq is concentration of horizontal groundwater influx [mg/L]. 
  7. Cw is concentration of a contaminant in liquid (water) phase [mg/L]. 
  8. Ca is concentration of a contaminant in vapor (air) phase [mg/L]. 
  9. Cmx(i) is mixed concentration in groundwater [W/V]. 
  10. Cs is concentration of a contaminant in solid phase [mg/Kg]. 
  11. Cs(z,0) is initial solid-phase concentration [mg/Kg]. 
  12. D is combined dispersion coefficient. 
  13. Da is gaseous phase diffusion coefficient in the pore air [ft2/yr]. 
  14. Dair is diffusion coefficient of the contaminant in the free air [ft2/yr]. 
  15. Dw is dispersion coefficient for the liquid phase contaminant in the pore water [ft2/yr]. 
  16. foc is fraction organic carbon of the soil [g/g]. 
  17. Kd is distribution coefficient between the solid phase and liquid phase [ml/g]. 
  18. KH is dimensional form of Henry's Law constant [atm-m3/mol]. 
  19. Koc is organic carbon-water partition coefficient [ml/g]. 
  20. h is head potential [L]. 
  21. H is Henry's partition coefficient between the air phase and water phase [dimensionless]. 
  22. Hd is penetration depth [ft]. 
  23. di is adjusted penetration depth for each column [L]. 
  24. hi,j is value of the head at the lattice point at (I,j)[L].
  25. i is discretized soil column cell (column index in finite difference grid). 
  26. j is row index in finite difference grid. 
  27. k is time level. 
  28. K is hydraulic conductivity [L/T]. 
  29. L is horizontal length dimension of the waste [ft]. 
  30. Lu is vertical distance from the source to the observation point (i.e., the water table) [L]. 
  31. m is iteration index. 
  32. M is total contaminant mass per unit volume of the soil. 
  33. n is total porosity of the soil: equals the sum of water filled porosity and air filled porosity. 
  34. N is head to a reasonable number of points. 
  35. qa is air flow velocity [ft/yr]. 
  36. qaq is the Darcy velocity in the aquifer [ft/yr]. 
  37. qx is specific flow rate in x direction [L/T]. 
  38. qy is specific flow rate in y direction [L/T]. 
  39. qw is water flow velocity (recharge rate) [ft/yr]. 
  40. R is universal gas constant (R = 8.2�10-5 atm-m3/mol�K). 
  41. t is time [yr]. 
  42. T is absolute temperature (�K = 273.16 + �C). 
  43. t0 is duration of solute release [yr]. 
  44. V is flow function. 
  45. z is vertical coordinate with positive being downward. 
  46. aL is longitudinal dispersivity of the vadose zone [ft]. 
  47. av is transverse (vertical) dispersivity of the aquifer [ft]. 
  48. Dt is time increment. 
  49. Dx is distance of lattice point in horizontal space [L]. 
  50. Dy is distance of lattice point in vertical space [L]. 
  51. g is decay rate of the solute source due to either degradation or flushing by the infiltration [1/yr]. 
  52. m is first order decay rate of a contaminant : in this model, for simplicity, it is assumed that mw = ma = ms = m
  53. mw is first order decay rate of a contaminant in water phase [1/yr]. 
  54. ma is first order decay rate of a contaminant in gaseous phase [1/yr]. 
  55. ms is first order decay rate of a contaminant in solid phase [1/yr]. 
  56. v is seepage velocity. 
  57. q is combined retardation factor. 
  58. qw is volumetric water content (volume of water / total volume) [ft3/ft3]. 
  59. qa is air-filled porosity (volume of air / total volume) [ft3/ft3]. 
  60. rb is bulk density of the soil [gr/cm3].

Review Questions

Last modified: Oct 15, 1999
VG Model/ Samuel Lee / VADOSE.NET