ABSTRACT
Groundwater flow and contaminant transport in aquifers are strongly influenced by the geological heterogeneity at various scales. This research has led to a better conceptual understanding of the transport mechanisms in various types of heterogeneous formations: single scale heterogeneity such as stationary continuous Gaussian and discrete Markovian fields and multiple scale heterogeneity such as compound non-stationary fields. The Markov chain model can address parametric variability. The spatial structure is characterized by conditional probabilities which are more interpretative in a geological sense and easier to estimate from soft geological information and the available hard data than auto-covariance or variogram functions. Various transport mechanisms (Fickian: diffusive dispersion, non-Fickian: sub-diffusive dispersion and superdiffusive dispersion) are observed in the simulations. These mechanisms are controlled by the spatial arrangements of the various geological units, by the extension of the source perpendicular to the global flow direction, and by the method of characterization of the heterogeneous medium.
