Numerical analysis of transport of landfill pollutants in unsaturated soil layer

The landfill site was idealized as three-layer strata composed of a compacted clay liner,an underlying unsaturated deposit and a layer of aquifer below the landfill.For such a system,one-dimensional mathematical equation for governing landfill pollutant transport through the three-layer strata was established.In the proposed model,steady-state unsaturated moisture distributions were employed in the dispersion-advection equation to simulate the transient distribution of contaminant in the strata beneath landfill.For the compacted clay liner,nonlinear equation of equilibrium sorption for the contaminant was employed,while the linear equation of equilibrium sorption was used for the unsaturated soil layer.The proposed equation of pollutant transport was numerically solved and comparative computations for varying parameters were made to examine the effect of various factors on the transport process of pollutants in each individual layers of the strata.