HR: 16:00h
AN: H24C-01 INVITED     [Abstracts]
TI: Geophysical Constraints on Contaminant Transport Modeling in Highly Heterogeneous Aquifers
AU: * Zheng, C
EM: czheng@ua.edu
AF: University of Alabama, Department of Geological Sciences, Tuscaloosa, AL 35487 United States
AU: Bowling, J C
EM: Jerry.Bowling@bp.com
AF: University of Alabama, Department of Geological Sciences, Tuscaloosa, AL 35487 United States
AU: Rodriguez, A B
EM: rodriguezanton@gmail.com
AF: University of North Carolina, Institute of Marine Sciences, Morehead City, NC 28557 United States
AU: Harry, D L
EM: dharry@cnr.colostate.edu
AF: Colorado State University, Department of Geosciences, Fort Collins, CO 80523 United States
AB: Because of the prevalent heterogeneity in the subsurface environment, a massive amount of hydrogeological data is usually required for 3-D characterization and modeling of groundwater flow and contaminant transport processes at an aquifer site. Traditionally monitoring and pumping wells are used to estimate aquifer hydraulic properties, which are expensive and provide only a limited point coverage of the site under investigation. In contrast, surface geophysical methods such as radar, electrical, and seismic methods provide dense spatial coverage, and allow investigators to acquire a large quantity of data quickly and inexpensively. While geophysical data can only be linked indirectly to hydrogeological attributes of an aquifer such as hydraulic conductivity, porosity, or plume migration, in some instances quantitative relationships can be established between geophysical data and hydrogeological attributes. This makes it very attractive to use geophysical methods as complementary or alternative means of providing quantitative estimates of hydrogeological parameters needed for groundwater modeling studies. This presentation discusses recent studies at a well-known tracer experiment site in Columbus, Mississippi where ground penetrating radar (GPR), direct-current resistivity, and seismic reflection data were collected to characterize a shallow fluvial aquifer. These data provide valuable constraints for flow and transport models developed to simulate and analyze a large-scale natural-gradient tracer test at the site. In particular, the data from one borehole flowmeter test collected during the original site description were used to calibrate the electrical resistivity data to hydraulic conductivity using a log-log relationship. Application of this relationship transforms the 3D electrical resistivity data into a 3D description of hydraulic conductivity. The simulated tracer plume based on the geophysically-derived hydraulic conductivity distribution agrees with the observed plume as well as does the simulated plume based on the hydraulic conductivity distribution derived from over 3000 flowmeter point measurements.
DE: 1832 Groundwater transport
DE: 1835 Hydrogeophysics
SC: Hydrology [H]
MN: Fall Meeting 2005