Design for a manually controlled multiple
electrode electrical resistivity array for student geophysical surveys
Smoyer,
Justin,
Kuhn,
Michelle, Friehauf,
Kurt, and Quinn,
Paul V.
Sr., 2006, Design
for a manually
controlled multiple electrode
electrical resistivity array for student geophysical surveys
[abs]:
Geological Society of America Northeastern Section – 41st Annual
Meeting (20–22 March 2006), Harrisburg, PA, Program with Abstracts, v.
38, no. 2, p. 89.
To
facilitate rapid collection of electrical resistivity data for a
groundwater study in karst terrain, we designed and constructed a 56
electrode array controlled with a manual switching box. The switchbox
allows directing current to electrodes using Wenner or Schlumberger
arrangements for vertical sounding on several centers after only one
emplacement of electrodes or Dipole-Dipole arrangements for measuring
pseudo-sections.
The rate of data collection improved most with longer node spacing and
when operated by fewer students because moving the electrodes was the
slowest step in the data collection procedure. Results of data for the
same test site using traditional four-electrode Wenner array to
determined depth to the base of the plow zone and depth to bedrock are
virtually identical to those measured with the big array (R-squared =
0.99).
The spacing between electrodes is 3 meters, allowing a maximum spacing
with the Wenner array of 55 meters. Data analysis using a spreadsheet
helps students understand the concepts underlying their data
interpretation. For undergraduate student hydrogeology projects, the
instrument is a low cost alternative to commercial multi-node arrays
and all materials are readily available.
