HR: 0800h
AN: H41B-0411    [Abstracts]
TI: Comparing Ideal and Field Tracer Transport in Fractured Bedrock using Ground Penetrating Radar
AU: * Becker, M W
EM: mwbecker@geology.buffalo.edu
AF: Department of Geology, University at Buffalo, SUNY, 876 NSC, Buffalo, NY 14260 United States
AU: Pardy, J S
EM: jtalley@gmail.com
AF: Golder Associates Inc., 3730 Chamblee Tucker Road, Atlanta, GA 30341 United States
AU: Baker, G S
EM: gbaker@tennessee.edu
AF: Department of Earth and Planetary Sciences, University of Tennessee, 306 Earth and Planetary Sciences Building, Knoxville, TN 37996-1410 United States
AB: The extraction of transport parameters from tracer experiments requires an assumption of flow field geometry. Determination of effective porosity, for example, requires an estimate of the swept area (the area encountered by the tracer from injection to detection). The error in estimated effective porosity is directly proportional to the error in estimated swept area. Swept area is difficult to anticipate in fractured bedrock due to the heterogeneous nature of the hydraulic conductivity field. We present a study in which decimeter scale forced- and natural-gradient tracer experiments in a subhorizontal rock fracture were imaged using surface ground penetrating radar (GPR). Swept area was estimated through imaging of saline tracer injected in a 7.6 m deep fracture. We found that tracer migration imaged by GPR differed significantly from predictions based upon ideal flow-field geometry. Images of actual tracer experiments are compared to idealized models of the same experiments to investigate the importance of the flow field geometry to the accurate estimation of transport parameters in fractured bedrock.
DE: 0925 Magnetic and electrical methods (5109)
DE: 1832 Groundwater transport
DE: 1835 Hydrogeophysics
DE: 5104 Fracture and flow
SC: Hydrology [H]
MN: Fall Meeting 2005