RELATING CONCEPTUAL MODELS OF HIERARCHICAL STRATAL ARCHITECTURE TO CONCEPTUAL MODELS FOR PLUME SPREADING

Sedimentary deposits are conceptualized as having a hierarchy of stratal unit types of different length scales, and a corresponding hierarchy of permeability subpopulations. While all scales may be relevant to modeling/conceptualizing plumes in some problems, and some scales may be relevant to modeling/conceptualizing plumes in all problems, all scales are probably not relevant to modeling/conceptualizing plumes in all problems. For problems where only larger scales of heterogeneity are relevant, and where numerical models are used to conceptualize mass transport processes, we can represent stratal architecture directly in the grid. However, if smaller-scale heterogeneity is also relevant, an upscaling method may be required. If upscaling methods involve lumped measures of heterogeneity, there are advantages to using lumped measures that are directly related to conceptual models of the stratal hierarchy and to quantifiable physical attributes such as proportions and lengths of unit types.