Deterministic Modeling of Dispersion in Heterogeneous Permeable Media

Abstract

Numerical experiments show that variations of an order of magnitude in transmissivity or hydraulic conductivity can cause significant dispersion even when relatively small values of dispersivity are assumed. Such variations should be represented in a deterministic model of solute transport in order to describe the flow field adequately and to realistically simulate dispersion. In an example of a field application to an alluvial aquifer, a satisfactory match to observed field data was obtained using a small (0.01 m) value of longitudinal dispersivity and a grid spacing fine enough to show field‐scale alluvial heterogeneities. When large (~30 m) values of longitudinal dispersivity were used, computed solute concentrations were about half of observed values in parts of the aquifer. Modeling efforts with grid spacings two to six times wider than alluvial channels in the aquifer produced ground‐water flow and solute‐transport simulations which did not adequately match field data.

Terrigenous Clastic Depositional Systems

“…Facies interpretation allows selection of appropriate analogs, guides interpolation of quantitative data, indicates the requisite sample densities and boundary conditions for statistical characterization, and geologically conditions realistic input parameters for flow simulations (Smith and Schwartz 1981;Gillham and Cherry 1982;Davis 1986;Weber 1986;Bryant and Flint 1993;Martin 1993;Slatt and Galloway 1993). Our thesis, shared by many petroleum geologists, hydrogeologists, and engineers, is that this exacting task is most efficiently and accurately accomplished within the context of a genetic facies framework.…”

Analysis of the anomalous scale-dependent behavior of dispersivity using straightforward analytical equations: Flow variance vs. dispersion

“…For example, Domenico and Robbins [1984] demonstrate t h a t using an (n-l)-dimensional model t o model an n-dimensional physical system w i l l introduce a d i s p e r s i v i t y scale e f f e c t . Davis [1986] demonstrates t h a t t h e scale e f f e c t is a mathematical r e s u l t of r e p r e s e n t i n g a q u i f e r p r o p e r t i e s as mean values.…”

Karstic gypsum problems at wastewater stabilization sites in the Black Hills of South Dakota

“…In any event, fecal contamination of the collection gallery's water appears to have ceased after upgradient homes with septic tanks and drain fields were connected to the Spearfish city sewer system in 1980, and chloridelevelsin samples,whichhad reached a peak in 1977, also declined to background levels. Davis (1986) used chloride as an indicator of septic tank contamination in ground waterbecausehome watersofteners resultin chloride levels in wastewater that are far above background levelsof 1 to 2 mg/l near the collectiongallery.…”