HIERARCHICAL APPROACHES TO TRANSPORT IN HETEROGENEOUS POROUS-MEDIA

Most attempts to quantify heterogeneity have been based on the belief that a separation of scale exists between a highly heterogeneous "small" scale and a "large" scale which is homogeneous relative to the former. The major distinction between these two scales is that small scale variability is often irrelevant for the prediction of events on the large scale. While it is apparent that cases exist where there is a distinct dichotomy of scales, the more general (and frequent) case will be that heterogeneity exists at all scales. Hierarchical approaches to transport in porous media recognize the natural variability of geologic materials that serve as soils and aquifers. Recently, researchers have begun developing new theories and models of transport and transformation in heterogeneous porous media based on conceptual models of hierarchical spatial variability of geologic materials.