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Geophysical Surveys near the San Pedro River, Arizona

During the Spring semester, 2001, the University of Arizona Geophysics Field
Camp (GEN/GEOS 416/516) conducted geophysical surveys near the San Pedro River,
Arizona. This site is being investigated by the U.S. Geological Survey as part of a basinwide
study of water resources. Our geophysical investigation was designed to provide
information that will assist in this hydrogeological study. The surveys were conducted
near Boquillas Ranch (approximately 2 km south of Fairbank, AZ) and approximately 2
km north of Hereford, AZ.
Dipole-dipole and Schlumberger DC resistivity surveys were conducted at both
the Boquillas Ranch and Hereford sites. Depth to water table was approximately 10-20
meters at the Boquillas Ranch site and 0-to-1 0 meters at the Hereford site. The electrical
resistivities at depth at the Hereford site were unusually low for Arizona basin-fill
sediments (less than 10 ohm-m).
Transient electromagnetic (TEM) soundings were also recorded at both the
Boquillas Ranch and Hereford sites. Electrical resistivity models were determined that
were very similar to the DC resistivity models. In general, the TEM soundings were able
to provide similar information to the DC resistivity soundings with greater data
acquisition rates and with a smaller crew.
Electromagnetic induction (EM31 and EM34) surveys were run at the Hereford
site. Qualitatively, an electrical resistivity structure was found that was similar to the DC
resistivity survey and the TEM survey results (i.e. the resistivity decreased with
increasing depth of investigation).These data are not well suited, however, to quantitative modeling.
Seismic, magnetic, and gravity surveys were run at the Boquillas Ranch site.
These surveys provided useful background information on the geologic structure at this
site. They did not provide direct information on the hydrogeology at the site.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/624618
Date10 May 2001
CreatorsCallegary, James, Chamunda, Tafwachi, Dearman, Marnee, Drury, Amelia, Jannusch, Jennifer, Katako, Rollina, Mkwayaya, Mabvuto, Mohamedyahya, Elhafedh, Muzumara, Dorcas, Russell, Simon, Sternberg, Ben, Wagner, Frank, Zgambo, Simon
ContributorsUniversity of Arizona
PublisherLASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ)
Source SetsUniversity of Arizona
Languageen_US
Detected LanguageEnglish
TypeBook
RightsCopyright © Arizona Board of Regents
RelationLASI-01-1, http://www.lasi.arizona.edu/

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