Water quality at contaminated sites must be monitored.  Typically this involves water sampling from on-site monitoring wells , a time-consuming and labor intensive process.  I have developed an automated system for long-term geophysical monitoring through permanent vertical resistivity probes (right).  By connecting these probes to a CR1000 datalogger, several multiplexers, and a solar power supply (components from Campbell Scientific, Inc. shown below), the electrical response of the subsurface may be measured at specified intervals over long periods of time.  These measurements can then be related to the saturation state of the subsurface and/or chemical properties in contaminated sites.  Utilizing this relationship can decrease the need for manual sampling. 

This work was funded by the Michigan Space Grant Consortium Graduate Research Fellowship.

The system was developed and installed in 2005 (below) in a field near a pond in Van Buren County, Michigan.  The monitoring system functioned well over a test period of nearly three years in a wide variety of weather conditions.  The location of testing was not contaminated, and thus the results related primarily to the saturation state of the subsurface, with resistivity increases relating to decreased saturation state and resistivity decreases relating to increased saturation state.