Transport models for leachates from landfills

Abstract

During the last ten years, transport models to describe the solute migration in the subsurface were more and more developed. The simulation of solute transport can include the main processes influencing the amount of spreading, as advection, dispersion/diffusion, sorption and degradation. To use a mathematical model with confidence, it is important to have an insight into the assumptions und limitations describing the movement of solutes. These restrictions depend on the type of hydrogeology, on the type of solution and on important processes influencing the migration. Generally, the best validation of simulation and field measurements is available for the advective flow in porous media. Strong differences are to state for simulations with a high dispersive migration of solutes. This is given for cases with a very heterogeneous aquifer and high contrasts in the composition of the aqueous solution. A proper simulation of sorption and degradation is possible for a simplification of the natural conditions only. To model the transport of leachates from a landfill, a better understanding of sorption and degradation processes is necessary. Geochemical models can provide important informations. Because of the high complexity of the aqueous solution leaching from a landfill, assistant laboratory and field studies are necessary to deliver the basics for the geochemical approach. The article gives an overview on the limitations and restrictions using a transport model to simulate the migration of leachates.