HR: 0800h
AN: H51A-0340    [Abstracts]
TI: Two-Dimensional Solute Transport in an Aquifer-Aquitard System
AU: * Zhan, H
EM: zhan@geo.tamu.edu
AF: Texas A&M University, Department of Geology and Geophysics, MS 3115, College Station, TX 77843
AU: Sun, D
EM: sunx0094@yahoo.com
AF: Hardin-Simmons University, Department of Geology, POB 16164, Abilene, TX 79698
AB: We have investigated solute transport in an aquifer bounded by an upper aquitard and a lower aquitard or bedrock. The present conceptual models of solute transport in aquitard-aquifer systems often ignore the solute diffusion into the aquitards. A few studies have considered aquitard diffusion, but they have adopted a methodology used in fracture-matrix systems by treating the solute flux across the aquitard-aquifer interface as a volumetric sink/source term in the governing equation of transport in the aquifer. This simplification does not satisfy the mass conservation requirement rigorously and its accuracy is unclear. To illustrate the importance of aquitard diffusion, we have investigated two-dimensional transport of a fully penetrating and laterally infinitely long source in an aquitard-aquifer system. We have maintained continuity of concentration and vertical solute flux at the aquitard-aquifer interface. The concentrations in the aquitards and aquifers are obtained by applying Laplace transform to time and finite Fourier Transform to the vertical coordinates of the transport equations. The new solutions can be used to calculate the spatial and temporal distributions of solute in the aquifer and aquitard, and to calculate the ratio of mass diffused into the aquitard over the mass remained in the aquifer. Our investigation indicates that previous approximate solutions based on volumetric sink/source approaches often did not correctly predict the mass flux into the aquitards. The new approach developed in this paper provides physically based solutions of solute transport in an aquifer-aquitard system.
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: Fall Meeting 2005