Water Resources Research Act Program

Details for Project ID 2019TX253B

Electrical Resistivity Tomography (ERT) parameter adaptation for seasonal variations

Institute: Texas
Year Established: 2019 Start Date: 2019-05-31 End Date: 2020-05-30
Total Federal Funds: $4,950 Total Non-Federal Funds: $9,900

Principal Investigators: Dr. Mark E. Everett

Project Summary: If the upper few meters of soil have a low electrical conductivity (ie. are relatively dry), electrical resistivity tomography can characterize groundwater sources down to the bedrock (~100 m deep) of the Brazos River Alluvial Aquifer. However, after a heavy rainstorm, the upper few meters of the soil become saturated, thereby raising electrical conductivity and decreasing electrical penetration depth to only a few meters under current parameters. We will conduct repeated ERT surveys adjacent to water monitoring wells over several seasons, systemically varying instrument parameters to determine which configurations generate electrical resistivity tomograms matching the adjacent water well ground truth and under which conditions. We will use these results to make the ERT deployable under a wide range of soil conductivities and thereby deployable to study fluvial stratigraphy and groundwater flow in similar floodplains worldwide. According to the 2017 Texas State Water Plan, planning for future use necessitates knowing the volume of available groundwater. The volume of available groundwater is a dynamic value, and this research will provide Texas and other regions with a non-invasive, geophysical method that is capable both of accurately providing these dynamic values for groundwater volumes and flow rates and of operating year round.