HR: 08:45h
AN: H21A-04    [PDF]
TI: A Comparison of Surface and Surface-Borehole ERT Arrays for Monitoring Subsurface Hydrologic Processes at the INEEL Site
AU: * Furman, A
EM: alex@hwr.arizona.edu
AF: Hydrology and Water Resources, Univ. of Arizona, Tucson, AZ 85721 United States
AU: Ferre, T P
EM: ty@hwr.arizona.edu
AF: Hydrology and Water Resources, Univ. of Arizona, Tucson, AZ 85721 United States
AU: Heath, G
EM: heatgl@inel.gov
AF: Geophysics, Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID 83415 United States
AB: Electrical resistivity tomography (ERT) is emerging as a leading tool for tracking hydrological processes at intermediate scales. Uses include the characterization of geological structure, slowly varying water contents, and rapidly changing water content or solute concentration during infiltration and flushing. The technique makes use of the simultaneous interpretation of 10's to 1000's of individual measurements to characterize multidimensional electrical conductivity distributions in the subsurface. Although ERT has been used widely in subsurface hydrology, some major limitations still exist to its optimal application. Specifically, data acquisition is to be optimized, and the combined effects of multiple components that contribute to the bulk electrical conductivity (i.e. water content, solute concentration, and medium properties) must be identified to allow for more quantitative analysis of heat or mass transport. This can be achieved through improved survey design, which combines hydrologic understanding in the identification of suitable ERT targets and optimization of data acquisition for hydrologic interpretation. We demonstrate that the wise selection of the arrays composing a survey can improve the ability to characterize subsurface hydrologic processes. The selection is based on comparisons of the sampling volumes of surface based ERT arrays with those that make use of both surface and borehole electrodes. The method is applied to a specific example of vadose zone monitoring at the Idaho National Environmental and Engineering Laboratory (INEEL).
DE: 0925 Magnetic and electrical methods
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
DE: 5109 Magnetic and electrical properties
SC: Hydrology [H]
MN: 2003 Fall Meeting