Contaminant dispersion with axial input sources in soil media under non-linear sorption.

Contaminant transport in a soil formation is described by advection dispersion equation. In this study, a horizontal and transversal contaminant transport along transient groundwater flow under non-linear sorption is solved numerically to examine the contaminant distribution profiles in finite soil media. The horizontal and transversal pore-water seepage velocities are defined as varying exponentially with time. Dispersion is considered directly proportional to the first power of the pore-water velocity. Axial input sources varying exponentially with time are assigned along the two-dimensional coordinate axes. For approximating the governing solute transport equation into algebraic equations, Crank-Nicolson (CN) and alternating direction implicit (ADI) methods are used. Both the numerical solutions are illustrated graphically with the help of computer software for various hydrological input data. In a special case, the numerical solutions are also compared with an approximate solution obtained by PDEtool. The comparison is performed with the help of contour plots. The CN method gives more accurate result than ADI method for the present model problem.