Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at an average sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release includes the averaged and culled AEM data along all flight lines that were used to produce the final resistivity models (https://www.sciencebase.gov/catalog/item/5ca6a4e6e4b0c3b0064c2c2b). Digital data of the processed soundings are provided and fields are defined in the data dictionary (https://www.sciencebase.gov/catalog/item/5d0814b9e4b0e3d3115bdab6). An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at a nominal sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release includes minimally processed (raw) AEM data, as well as unprocessed and processed (diurnally corrected and draped to terrain) magnetic data, and unprocessed and processed (following International Atomic Energy Agency Technical Report procedures) radiometric data, all as supplied by CGG Canada Services, Ltd. (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5). Data acquisition and minimal processing was conducted by CGG Canada Services, Ltd. and described in detail in the contractor's report. Digital data from production flights are provided, and data fields are defined in the data dictionary. An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES International Atomic Energy Agency, 1991, Airborne Gamma Ray Spectrometer Surveying, Technical Reports Series No. 323, IAEA, Vienna. U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at a nominal sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release includes minimally processed (raw) AEM data, as well as unprocessed and processed (diurnally corrected and draped to terrain) magnetic data, and unprocessed and processed (following International Atomic Energy Agency Technical Report procedures) radiometric data, all as supplied by CGG Canada Services, Ltd. (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5). Data acquisition and minimal processing was conducted by CGG Canada Services, Ltd. and described in detail in the contractor's report. Digital data from production flights are provided, and data fields are defined in the data dictionary. An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES International Atomic Energy Agency, 1991, Airborne Gamma Ray Spectrometer Surveying, Technical Reports Series No. 323, IAEA, Vienna. U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at a nominal sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release includes minimally processed (raw) AEM data as supplied by CGG Canada Services, Ltd. (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5), the fully processed (averaged and culled) sounding data (https://www.sciencebase.gov/catalog/item/5d0814b9e4b0e3d3115bdab6), and laterally constrained inverted resistivity depth sections along all flight lines (https://www.sciencebase.gov/catalog/item/5ca6a4e6e4b0c3b0064c2c2b), as well as unprocessed and processed (diurnally corrected and draped to terrain) magnetic data (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5), and unprocessed and processed (following International Atomic Energy Agency Technical Report procedures) radiometric data (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5). Data acquisition and minimal processing were conducted by CGG Canada Services, Ltd. and described in detail in the contractor's report. Digital data from production flights are provided, and data fields are defined in the data dictionary. A total field magnetic anomaly grid and a ternary radiometric image are provided as well (https://www.sciencebase.gov/catalog/item/5cd0ad9de4b09b8c0b79a53f). An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES International Atomic Energy Agency, 1991, Airborne Gamma Ray Spectrometer Surveying, Technical Reports Series No. 323, IAEA, Vienna. U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at a nominal sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release includes minimally processed (raw) AEM data as supplied by CGG Canada Services, Ltd. (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5), the fully processed (averaged and culled) sounding data (https://www.sciencebase.gov/catalog/item/5d0814b9e4b0e3d3115bdab6), and laterally constrained inverted resistivity depth sections along all flight lines (https://www.sciencebase.gov/catalog/item/5ca6a4e6e4b0c3b0064c2c2b), as well as unprocessed and processed (diurnally corrected and draped to terrain) magnetic data (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5), and unprocessed and processed (following International Atomic Energy Agency Technical Report procedures) radiometric data (https://www.sciencebase.gov/catalog/item/5ca6ce7ee4b0c3b0064c2ce5). Data acquisition and minimal processing were conducted by CGG Canada Services, Ltd. and described in detail in the contractor's report. Digital data from production flights are provided, and data fields are defined in the data dictionary. A total field magnetic anomaly grid and a ternary radiometric image are provided as well (https://www.sciencebase.gov/catalog/item/5cd0ad9de4b09b8c0b79a53f). An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES International Atomic Energy Agency, 1991, Airborne Gamma Ray Spectrometer Surveying, Technical Reports Series No. 323, IAEA, Vienna. U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil type. The survey was flown at an average sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. A total field magnetic anomaly Grid eXchange File (.gxf) grid and a ternary radiometric geotiff image derived from the flight line data are provided (https://www.sciencebase.gov/catalog/item/5cd0ad9de4b09b8c0b79a53f). Additional details are provided in the processing steps. An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil type. The survey was flown at an average sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. A total field magnetic anomaly Grid eXchange File (.gxf) grid and a ternary radiometric geotiff image derived from the flight line data are provided (https://www.sciencebase.gov/catalog/item/5cd0ad9de4b09b8c0b79a53f). Additional details are provided in the processing steps. An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at an average sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release item includes elevation surfaces that represent the top and bottom of the alluvial aquifer, as defined by its electrical resistivity transitions, that are used to support development of an inset groundwater-flow model. An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired in late February to early March 2018 along 2,364 line-kilometers in the Shellmound, Mississippi study area. Data were acquired by CGG Canada Services, Ltd. with three different helicopter-borne sensors: the CGG Canada Services, Ltd. RESOLVE frequency-domain AEM instrument that is used to map subsurface geologic structure at depths up to 100 meters, depending on the subsurface resistivity; a Scintrex CS-3 cesium vapor magnetometer that detects changes in deep (hundreds of meters to kilometers) geologic structure based on variations in the magnetic properties of different formations; and a Radiation Solutions RS-500 spectrometer that detects the abundance of natural radioelements potassium, uranium, and thorium in the upper 20-30 cm that is used to determine differences in soil constituents. The survey was flown at an average sensor flight height of 30 m above terrain to form block-style coverage with 250 to 1,000-meter spaced east-west flight lines. This data release item includes elevation surfaces that represent the top and bottom of the alluvial aquifer, as defined by its electrical resistivity transitions, that are used to support development of an inset groundwater-flow model. An important driver for this survey is a managed aquifer recharge pilot project developed by the U.S. Department of Agriculture Agricultural Research Service investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline by direct injection into the Mississippi River Valley Alluvial Aquifer (MRVA). Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot engineering study and will be even more important for potential future large-scale engineering projects and groundwater model development efforts. REFERENCES U.S. Geological Survey, The National Map, 2017, 3DEP products and services: The National Map, 3D Elevation Program Web page, accessed October 2018 at https://nationalmap.gov/3DEP/3dep_prodserv.html.

Shallow soil characteristics were mapped near Shellmound, Mississippi, using the DualEM 421 electromagnetic sensor in October 2018. Data were acquired by towing the DualEM sensor on a wheeled cart behind an all-terrain vehicle (ATV), with the sensor at a height of 0.432 meters (m) above the ground surface. Approximately 175 line-kilometers of data were acquired over an area of nearly four square-kilometers, with 25 m separation between survey lines. Data were manually edited for noise sources such as powerlines or other buried structures and averaged to regular output soundings every 5 m along survey lines. The processed data were inverted to recover models of electrical resistivity structure as a function of depth at each sounding location using a spatially constrained inversion. This data release contains the raw and processed data, as well as inverted resistivity models. Model results show typical depth of investigation from about 4 – 6 m, with spatial variability in mapped electrical resistivity characteristic of fluvial deposition of sediments in channels and scroll bar features adjacent to the Tallahatchie River and nearby abandoned meander channels.