A Low‐Cost, In Situ Resistivity and Temperature Monitoring System

Abstract

We present a low-cost, reliable method for long-term in situ autonomous monitoring of subsurface resistivity and temperature in a shallow, moderately heterogeneous subsurface. Probes, to be left in situ, were constructed at relatively low cost with an electrode spacing of 5 cm. Once installed, these were wired to the CR-1000 Campbell Scientific Inc. datalogger at the surface to electrically image infiltration fronts in the shallow subsurface. This system was constructed and installed in June 2005 to collect apparent resistivity and temperature data from 96 subsurface electrodes set to a pole-pole resistivity array pattern and 14 thermistors at regular intervals of 30 cm through May of 2008. From these data, a temperature and resistivity relationship was determined within the vadose zone (to a depth of ~1 m) and within the saturated zone (at depths between 1 and 2 m). The high vertical resolution of the data with resistivity measurements on a scale of 5-cm spacing coupled with surface precipitation measurements taken at 3-min intervals for a period of roughly 3 years allowed unique observations of infiltration related to seasonal changes. Both the vertical resistivity instrument probes and the data logger system functioned well for the duration of the test period and demonstrated the capability of this low-cost monitoring system.

A low‐cost, versatile data logging system for ecological applications

“…If volume is not so crucial, future customization opportunities can be maximized by soldering female header pins to the custom‐made circuit board and just attaching the Arduino Nano, as well as not cutting the ICSP header pins. Using this method the fully assembled data logger measures 62 × 36 × 26 mm and weighs approximately 29.1 g. For comparison, the CR1000 logger (Campbell Scientific, Utah), a commercially available device used in several ecological studies (e.g., Kavanaugh and Moore ; Sherrod et al ; McDaniel et al ), measures 239 × 102 × 61 mm and weights 1.0 Kg without batteries. Our system provides six analog and four digital channels.…”

Advances in interpretation of subsurface processes with time‐lapse electrical imaging

“…Coupled with equally autonomous data processing and inversion on the software end, this provides the opportunity to execute real‐time autonomous monitoring of subsurface process through time‐lapse ERI (Versteeg et al ., ; Johnson et al ., ). In addition to commercially available systems, the availability of highly customizable ‘smart’ electrical hardware components and advanced, high‐level control software have facilitated the development of capable and inexpensive custom ‘home grown’ ERI survey instruments (Sherrod et al ., ).…”

Geophysical Methods for Monitoring Temperature Changes in Shallow Low Enthalpy Geothermal Systems

“…If it is not the case, a correction term must be applied before deriving temperatures. The process is similar to temperature corrections applied to time-lapse ERT results when monitoring other phenomena [40,[58][59][60].…”

“…As a result, temperature corrections in time-lapse (monitoring) series may be necessary to correct electrical resistivity tomography results in order to avoid misinterpretation when explaining resistivity changes linked to other physical processes such as changes in contamination or porosity [40,[58][59][60].…”