HR: 14:25h
AN: H33M-04    [Abstracts]
TI: Combined Hydraulic Tomography - Self Potential - Electrical Resistivity Tomography for Parameter Estimation in the Unconfined Aquifer at the Boise Hydrogeophysical Research Site
AU: * Barrash, W
EM: wbarrash@cgiss.boisestate.edu
AF: CGISS/Geosciences Boise State University, MG206 MS1536 1910 University Dr., Boise, ID 83725, United States
AU: Revil, A
EM: arevil@mines.edu
AF: Department of Geophysics Colorado School of Mines, 1500 Illinois St., Golden, CO 80401, United States
AU: Cardiff, M
EM: mcardiff@stanford.edu
AF: Civil and Env. Engineering Dept Stanford University, 380 Panama Mall Terman M-13, Stanford, CA 94305, United States
AU: Johnson, T
EM: timothy.johnson@inl.gov
AF: Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-2107, United States
AU: Malama, B
EM: bmalama@cgiss.boisestate.edu
AF: CGISS/Geosciences Boise State University, MG206 MS1536 1910 University Dr., Boise, ID 83725, United States
AU: Rizzo, E
EM: rizzo@imaa.cnr.it
AF: Hydrogeosite Laboratory CNR-IMAA, C. da Fontanelle, Marisco Nuovo, 85052, Italy
AU: Miller, C
EM: camiller@cgiss.boisestate.edu
AF: CGISS/Geosciences Boise State University, MG206 MS1536 1910 University Dr., Boise, ID 83725, United States
AU: Straface, S
EM: straface@dds.unical.it
AF: Dipartimento di Difesa del Suolo Universita della Calabria, Via P. Bucci, 42B, Rende, 87036, Italy
AB: A series of combined hydrogeophysical tests were conducted during a two-week period in June 2007 in the unconfined coarse fluvial aquifer at the Boise Hydrogeophysical Research Site (BHRS). The tests included three component experiments -- hydraulic tomography (HT), self potential measurements (SP), and electrical resistivity tomography (ERT) -- which will be used, both individually and jointly, to image subsurface heterogeneity. The major aim of the tests is the estimation of the hydraulic conductivity (K) distribution from hydrologic responses and from SP anomalies under both transient and steady state pumping conditions. The ERT results provide independent information both for the electrical conductivity distribution (which may correlate with subsurface hydrologic parameters) and for the use of this distribution in the SP analysis. For HT, the dipole (pumping and injection, conservative) test configuration was used to achieve steady state as rapidly as possible and also to generate two high-gradient disturbance zones per test, rather than one as in conventional pumping tests. The investigated volume is the central region of the BHRS which is roughly 30m x 30m x 20m and is known to have laterally varying thickness-averaged K variation as wells as layered and patchy heterogeneity. This area was instrumented with offset SP and ERT electrode grids at the surface, transducers in wells, and also SP electrodes in seven wells including the pumping and injection wells; river boundary conditions also were monitored. Preliminary reviews of raw data by respective method teams suggest (pseudo) hydrologic steady state was reached at most observation wells, SP anomalies are clearly observable (but asymmetrical for most tests), and ERT data are repeatable and capture water table drawdown and buildup anomalies. In addition, stage variations in the Boise River adjacent to the BHRS propagated throughout the site and were observed at wells. Although flow rates in the river are controlled, aquifer responses to changes in river stage are analogous to natural stream- aquifer interactions, and the magnitude and timing of these responses at wells can provide additional information for inverse modeling.
UR: http://cgiss.boisestate.edu/~billc/EPA3/ht-sp.html
DE: 0925 Magnetic and electrical methods (5109)
DE: 1828 Groundwater hydraulics
DE: 1835 Hydrogeophysics
DE: 1894 Instruments and techniques: modeling
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
SC: Hydrology [H]
MN: 2007 Fall Meeting