004-23-AMS - Electrical Resistivity Tomography System for Time-Lapse Monitoring

The Edwards Aquifer Authority (EAA) is interested in purchasing a surface-based system for generating electrical resistivity tomography (ERT) images of the deep vadose zone for hydrogeological investigations. The ERT system will be deployed primarily for time-lapse monitoring of changes in vadose zone water storage in soil and epikarst in the upper ~150 feet of the subsurface at various research sites in the Edwards Aquifer Region in Central Texas. Some sites will be outfitted with permanently buried cables and electrodes for high-frequency (e.g., sub-daily) time-lapse ERT imaging. Other sites will be imaged intermittently (e.g., bi-weekly) with portable equipment.The ERT system must be compatible with both applications.