Open AccessAnalysis of the anomalous scale-dependent behavior of dispersivity using straightforward analytical equations: Flow variance vs. dispersion
Author(s) -
B.B. Looney,
M. T. Scott
Publication year - 1988
Language(s) - English
Resource type - Reports
DOI - 10.2172/353229
Subject(s) - dispersion (optics) , advection , variance (accounting) , statistical physics , scale (ratio) , flow (mathematics) , porous medium , field (mathematics) , mechanics , statistics , mathematics , physics , geology , thermodynamics , geotechnical engineering , porosity , optics , accounting , quantum mechanics , pure mathematics , business
Recent field and laboratory data have confirmed that apparent dispersivity is a function of the flow distance of the measurement. This scale effect is not consistent with classical advection dispersion modeling often used to describe the transport of solutes in saturated porous media. Many investigators attribute this anomalous behavior to the fact that the spreading of solute is actually the result of the heterogeneity of subsurface materials and the wide distribution of flow paths and velocities available in such systems. An analysis using straightforward analytical equations confirms this hypothesis. An analytical equation based on a flow variance approach matches available field data when a variance description of approximately 0.4 is employed. Also, current field data provide a basis for statistical selection of the variance parameter based on the level of concern related to the resulting calculated concentration. While the advection dispersion approach often yielded reasonable predictions, continued development of statistical and stochastic techniques will provide more defendable and mechanistically descriptive models