Characterizing aquifer structure with airborne and towed time-domain EM
The Remote Sensing Hydrology lab is fortunate to have one of the few tTEM systems in the United States. The tTEM is a towed Time-domain ElectroMagnetic system that is capable of imaging the subsurface resistivity to a depth of ~60 m. The resistivity values can then be related to sand, clay, bedrock, groundwater salinity, and in some cases water table data to improve the spatial characterization of the aquifer. The tTEM can acquire roughly 100 km of data per day, making it an excellent tool for groundwater studies in most water management districts.
Currently, we are using tTEM data to improve characterization of the Kansas River Alluvial Aquifer in Kansas, the San Luis Valley of Colorado and the Parowan Valley aquifer in southwest Utah. These data will be used to estimate spatial variation in hydraulic conductivity, the presence of confining layers, and the volume of clay that could increase the risk of land subsidence.
Funding
NASA, NSF
Study Areas
Utah, Colorado, Kansas, California
Papers
Li, J.*, Smith, R.G., Grote, K., Bergsted, J., Aquifer Characterization Using Towed Time-domain Electromagnetics in a Variably Saturated, Data-Sparse Region, Under Review in Journal of Applied Geophysics
Smith, R.G., R. Knight, 2019, Modelling land subsidence using InSAR and Airborne Electromagnetic Data. Water Resources Research. [pdf]
Knight, R., Smith, R.G., Asch, T., Abraham, J., Cannia, J., Viezzoli, A., Fogg, G., 2018, Mapping Aquifer Systems with Airborne Electromagnetics in the Central Valley of California. Groundwater. [link]
Nordin, M., Smith, R.G., Knight, R., 2016, The use of color wheels to communicate uncertainty in the interpretation of geophysical data. The Leading Edge.
3D visualization of tTEM-derived subsurface resistivity in Kansas. Red colors indicate sands/gravels, blue colors indicate clays. Click here for an interactive plot.