Modeling solute transport in ground water at or near freezing : Ground Water V29, N1, Jan–Feb 1991, P21–25

Abstract

Under freezing or near-freezing conditions, temperature-induced viscosity changes, solute immobilization, and solute exclusion can affect field-scale solute transport in ground water. This can lead to concentration profiles significantly different from those predicted by models which do not account for these processes. A model (GWFREEZE) is presented which incorporates these processes into a two-dimensional transport equation for saturated porous media subject to a hydraulic head field that does not vary with time. Ground-water temperature can be expected to vary widely in some natural and artificial freezing and near-freezing situations. Spatially varying temperature fields cause spatial variations in the fluid viscosity field, especially near 0° C, where viscosity varies faster with temperature than at higher temperatures. GWFREEZE models these phenomena with a viscosity-dependent hydraulic conductivity that is a function of temperature. Solute exclusion is modeled by a variable exclusion coefficient (Ke) which represents the percentage of solute excluded at the freezing front. The freezing front is modeled as a planar no-flow boundary behind which solutes are immobilized and at which solutes are excluded.