The paper presents a 1D mathematical model for the simulation of the percolation fluxes throughout a
landfill for municipal solid waste (MSW). Specifically, the model was based on mass balance equations,
that enable simulation of the formation of perched leachate zones in a landfill for MSW. The model considers
the landfill divided in several layers evaluating the inflow to and outflow from each layer as well as
the continuous moisture distribution. The infiltration flow was evaluated by means of the Darcy’s law for
an unsaturated porous medium, while the moisture distribution evaluation has been carried out on the
basis of the theory of the vertically distributed unsaturated flow. The solution of the model has been
obtained by means of the finite difference method. The model has been applied to a semi-idealized landfill
located in Palermo landfill (Bellolampo). Specifically, field measurements were conducted to determine
the relationship between waste density and applied vertical strain. This relationship was then
used to relate vertical strain to waste porosity. The inflow rate to the system was simulated via a synthetic
hyetograph whose characteristics have been identified in a previous hydrologic study.
Three simulations, each with a different initial moisture content, were conducted. The model results
showed a different response of the landfill in terms both of flow rates throughout the landfill and moisture
profile. Indeed, the initial moisture content drastically influenced not only the formation of perched
leachate zones but also their extension. The model can be a useful tool in predicting potential for the formation
of perched leachate zones.