Assessment of Porous Media Heterogeneity by Inverse Plume Analysis

Abstract

AbstractResults from analysis of models of heterogeneous porous media indicate that inverse plume analysis has potential for use in delineating zones of differing characteristics within porous media even when the zones are not penetrated by a borehole. By analyzing the concentrations at pairs of points in a contaminant plume, the spatial distributions of apparent transverse dispersivity and source size are determined. Since dispersivity is an intrinsic property of a porous medium, spatial distributions of the apparent dispersivities obtained from inverse analysis of plumes are an indication of transitions in the character of the porous medium.Dispersivity values obtained by inverse plume analysis in heterogeneous porous media are “apparent” because the equation on which the analysis is based was developed under the assumption that the porous media is isotropic and homogeneous. In the case of heterogeneous porous media, the dispersivity value obtained at a given location by inverse plume analysis is affected by the spreading of the plume through different materials. Therefore, variations in dispersivity should be interpreted qualitatively for delineation of heterogeneity and not quantitatively as for input to numerical transport models.