Mississippi Alluvial Plain (MAP): Electrical Resistivity &amp; Facies Classification Grids

Electrical resistivity results from four regional airborne electromagnetic (AEM) surveys (Burton et al. 2024, Hoogenboom et al. 2023, Minsley et al. 2021, Burton et al. 2021) over the Mississippi Alluvial Plain (MAP) were combined by the U.S. Geological Survey (USGS) to produce three-dimensional (3D) gridded models and derivative hydrogeologic products. The 3D models and products were first published using data from the earlier two AEM regional surveys, labeled with the year “2020” (Minsley et al. 2021, Burton et al. 2021). The 3D resistivity models and select derivative products were later updated by incorporating additional data from the two later AEM surveys, labeled with the year “2022” (Burton et al. 2024, Hoogenboom et al. 2023). In both 2020 and 2022 versions, grids were discretized in the horizontal dimension to align with the 1 kilometer (km) x 1 km National Hydrogeologic Grid (NHG; Clark et al. 2018), and vertically discretized into both 5 meter (m) depth slices and 5 m elevation slices. 
Facies classes were defined to categorize materials expected to have similar hydrologic and geologic properties based on their electrical resistivity (i.e. low classes correspond to clays and silts with low permeability, and higher classes reflect larger grain sizes (sands, gravels) with expected higher permeability). In the 2020 version, 10 facies classes were used, and classes were further separated based on position relative to the base of the Mississippi River Valley Alluvial aquifer (MRVA) to capture geologic distinctions in addition to hydrogeologic. In the 2022 version, two new facies classes were added to the lower resistivity end (12 classes total) and no distinction was made based on the MRVA extent. All 3D grids were exported into NetCDF format and all metadata from the NetCDF files are provided within the accompanying XML NetCDF Markdown Language file (*.ncml).
Burton, B.L., Adams, R.F. Adams, Minsley, B.J., Pace, M.D.M., Kress, W.H., Rigby, J.R., and Bussell, A.M., 2024, Airborne electromagnetic, magnetic, and radiometric survey of the Mississippi Alluvial Plain, March 2018 and May - August 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9KPK3UJ.
Hoogenboom, B.E., Minsley, B.J., James, S.R., and Pace, M.D., 2023, Airborne electromagnetic, magnetic, and radiometric survey of the Mississippi Alluvial Plain, Mississippi Embayment, and Gulf Coastal Plain, September 2021 - January 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P93DO0EO.
Burton, B.L., Minsley, B.J., Bloss, B.R., and Kress, W.H., 2021, Airborne electromagnetic, magnetic, and radiometric survey of the Mississippi Alluvial Plain, November 2018 - February 2019: U.S. Geological Survey data release, https://doi.org/10.5066/P9XBBBUU.
Clark, B.R., Barlow, P.M., Peterson, S.M., Hughes, J.D., Reeves, H.W., and Viger, R.J., 2018, National-scale grid to support regional groundwater availability studies and a national hydrogeologic database: U.S. Geological Survey data release, https://doi.org/10.5066/F7P84B24.
Minsley, B.J., James, S.R., Bedrosian, P.A., Pace, M.D., Hoogenboom, B.E., and Burton, B.L., 2021, Airborne electromagnetic, magnetic, and radiometric survey of the Mississippi Alluvial Plain, November 2019 - March 2020: U.S. Geological Survey data release, https://doi.org/10.5066/P9E44CTQ.

Tags: 3d, arkansas, arkansas-river, electromagnetic-surveying, electromagnetics, engineering-sciences, environment, geology-geophysics-and-geochemistry-science-center, geophysics, geoscientificinformation, geospatial-datasets, gggsc, groundwater, hydrogeology, illinois, louisiana, mississippi, mississippi-alluvial-plain, mississippi-river, mississippi-river-valley-alluvial-aquifer, missouri, mrva, resistivity, tennessee, three-dimensional, u-s-geological-survey, usgs, usgs-5f03a7bc82ce0afb2446e11f, water-availability-and-use-science-program, water-resources, wausp
Organization: Department of the Interior