TEM2Go

The Near Surface Observatory at the Bureau of Economic Geology has acquired a new geophysical instrument capable of acquiring profiles of the electrical conductivity of the ground from the surface to depths of 50 m or more. This instrument, called "TEM2Go" by TEMCompany, acquires data using the transient or time-domain electromagnetic induction method (TEM or TDEM), is carried across the landscape by two people with backpacks (fig. 1), is controlled by an app running on a smartphone or tablet, and displays inverted depth sections in real time. Researchers at the NSO have long used airborne and ground-based TEM methods to support geologic mapping, groundwater, and soil and water salinization studies, but this is the first TEM instrument at the NSO capable of rapidly acquiring electrical conductivity cross sections over walkable terrain. This instrument, one of the first of its kind worldwide, is already being used to support STATEMAP geologic mapping in Texas and a TWDB-sponsored study of the Brazos River Alluvium Aquifer near College Station, Texas. Similar instruments are begining to be used to locate critical groundwater resources in areas suffering humanitarian crises owing to lack of potable water.

TEM2Go
Figure 1. Near Surface Observatory researchers acquiring TEM2Go data at Commons Ford Ranch Metropolitan Park along the Colorado River, Austin, Texas, March 2026. The lead person carries the transmitter coil; the trail person carries the receiver coil about 15 meters behind the transmitter.


 

TEM2Go
Figure 2. An 800-m-long cross section along the lower (left) and intermediate (right) alluvial terraces of the Colorado River showing electrical resistivity (the inverse of conductivity) to depths of about 50 m. At this site, the electrically conductive material at the surface on the left half of the line is likely water-saturated terrace alluvium, which overlies more resistive limestone bedrock at a depth of 10 to 15 m. On the intermediate alluvial terrace, there’s a resistive layer at the surface that is likely the unsaturated zone in the alluvium and is underlain by conductive saturated alluvium and then resistive bedrock.


 

Drone view of TEM2Go in operation at Commons Ford Ranch Metropolitan Park, Austin, Texas. Video by John Andrews.

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