Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This data release includes the averaged and culled AEM data along all flight lines that were used to produce the final resistivity models for both surveys https://www.sciencebase.gov/catalog/item/5d76ba5ce4b0c4f70d01ff94 Digital data of the processed soundings are provided and fields are defined in the data dictionary https://www.sciencebase.gov/catalog/item/5d76bac9e4b0c4f70d01ff9d.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. 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 Xcalibur Multiphysics https://www.sciencebase.gov/catalog/item/624bd4a6d34e21f82763663c. Data acquisition and minimal processing were conducted by Xcalibur Multiphysics and described in detail in the contractor's reports. Digital data from production flights are provided, and data fields are defined in the data dictionaries.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. 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 Xcalibur Multiphysics https://www.sciencebase.gov/catalog/item/624bd4a6d34e21f82763663c. Data acquisition and minimal processing were conducted by Xcalibur Multiphysics and described in detail in the contractor's reports. Digital data from production flights are provided, and data fields are defined in the data dictionaries.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. 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 Xcalibur Multiphysics https://www.sciencebase.gov/catalog/item/624bd4a6d34e21f82763663c. Data acquisition and minimal processing were conducted by Xcalibur Multiphysics and described in detail in the contractor's reports. Digital data from production flights are provided, and data fields are defined in the data dictionaries.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021, along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP) and the Chicot Aquifer extent in the southeastern United States. These helicopter-based surveys collected data with a frequency-domain AEM system (Xcalibur Multiphysics RESOLVE), a cesium vapor magnetometer (Scintrex CS-3), and radiometric spectrometer (Radiation Solutions RS-500) at altitude of 30 meters (m) above the land surface. These sensors imaged a series of rivers and levees throughout these two areas focusing on water resources and infrastructure assessment. This data release includes minimally processed (raw) data, as supplied by the airborne survey contractor (Xcalibur Multiphysics), for all three sensors along all flight lines. Additionally, the AEM survey files contain the fully processed data (all corrections applied and any anomalies removed, but before any modeling), and inverted resistivity models (final modeled data) along all flight lines. Data files contained in this data release include: Contractor's report- Description of data acquisition and minimal processing as conducted by Xcalibur Multiphysics (Airborne Survey Contractor). Data were collected on the following 16 rivers: Rivers within the MAP boundary: Black, White, Big Sunflower, Little Sunflower, Ouachita, Tensas, Obion, Saline, Little Red, and Bogue Phalia. Rivers within the Chicot Aquifer extent : Mermentau, Calcasieu, Sabine, Vermillion, Bayou Teche and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers. Where possible, lines were flown along the toe of the levee both on the side adjacent to the river and on the side opposite the river. In addition, where possible, a third line was flown 91m (300 feet) offset from the toe of the levee opposite to the river. Additional processing was done on all levee lines and is described in the data dictionaries and processing step sections of the metadata included in the “Processed Data” and “Resistivity Models” child items of this data release. Seven gridded surveys were collected also: Four grids at different resolutions were collected over gravel bars within the Mississippi River 250 m Line Spacing Prairie Point Island 63 Crumrod 100 m Line Spacing White River 23 line-km at a 100 m line spacing over a property near Minter City, Mississippi (referred to as the Melton grid). 268 line-km at a 500 m spacing over a series of the drill core locations near Paragould, AR. Referred to in this release as the AR OSL grid. 100 line-km at variable spacings over Raccourci Old River, a relic oxbow near Batchelor, LA. Referred to in this release as the Raccourci grid. A dataset collected on small levees near Greenville, Mississippi, in March 2018 is also included in this data release. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This dataset was collected as an evaluation of the technical approach used on the more comprehensive surveys in the MAP and Chicot Aquifer extents. This dataset contains AEM data only (magnetic and radiometric data were not collected). Additional detail on flight line numbers and citations for the various methods used in the collection and processing of the radiometric data is included in the supplemental section.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021, along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP) and the Chicot Aquifer extent in the southeastern United States. These helicopter-based surveys collected data with a frequency-domain AEM system (Xcalibur Multiphysics RESOLVE), a cesium vapor magnetometer (Scintrex CS-3), and radiometric spectrometer (Radiation Solutions RS-500) at altitude of 30 meters (m) above the land surface. These sensors imaged a series of rivers and levees throughout these two areas focusing on water resources and infrastructure assessment. This data release includes minimally processed (raw) data, as supplied by the airborne survey contractor (Xcalibur Multiphysics), for all three sensors along all flight lines. Additionally, the AEM survey files contain the fully processed data (all corrections applied and any anomalies removed, but before any modeling), and inverted resistivity models (final modeled data) along all flight lines. Data files contained in this data release include: Contractor's report- Description of data acquisition and minimal processing as conducted by Xcalibur Multiphysics (Airborne Survey Contractor). Data were collected on the following 16 rivers: Rivers within the MAP boundary: Black, White, Big Sunflower, Little Sunflower, Ouachita, Tensas, Obion, Saline, Little Red, and Bogue Phalia. Rivers within the Chicot Aquifer extent : Mermentau, Calcasieu, Sabine, Vermillion, Bayou Teche and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers. Where possible, lines were flown along the toe of the levee both on the side adjacent to the river and on the side opposite the river. In addition, where possible, a third line was flown 91m (300 feet) offset from the toe of the levee opposite to the river. Additional processing was done on all levee lines and is described in the data dictionaries and processing step sections of the metadata included in the “Processed Data” and “Resistivity Models” child items of this data release. Seven gridded surveys were collected also: Four grids at different resolutions were collected over gravel bars within the Mississippi River 250 m Line Spacing Prairie Point Island 63 Crumrod 100 m Line Spacing White River 23 line-km at a 100 m line spacing over a property near Minter City, Mississippi (referred to as the Melton grid). 268 line-km at a 500 m spacing over a series of the drill core locations near Paragould, AR. Referred to in this release as the AR OSL grid. 100 line-km at variable spacings over Raccourci Old River, a relic oxbow near Batchelor, LA. Referred to in this release as the Raccourci grid. A dataset collected on small levees near Greenville, Mississippi, in March 2018 is also included in this data release. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This dataset was collected as an evaluation of the technical approach used on the more comprehensive surveys in the MAP and Chicot Aquifer extents. This dataset contains AEM data only (magnetic and radiometric data were not collected). Additional detail on flight line numbers and citations for the various methods used in the collection and processing of the radiometric data is included in the supplemental section.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021, along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP) and the Chicot Aquifer extent in the southeastern United States. These helicopter-based surveys collected data with a frequency-domain AEM system (Xcalibur Multiphysics RESOLVE), a cesium vapor magnetometer (Scintrex CS-3), and radiometric spectrometer (Radiation Solutions RS-500) at altitude of 30 meters (m) above the land surface. These sensors imaged a series of rivers and levees throughout these two areas focusing on water resources and infrastructure assessment. This data release includes minimally processed (raw) data, as supplied by the airborne survey contractor (Xcalibur Multiphysics), for all three sensors along all flight lines. Additionally, the AEM survey files contain the fully processed data (all corrections applied and any anomalies removed, but before any modeling), and inverted resistivity models (final modeled data) along all flight lines. Data files contained in this data release include: Contractor's report- Description of data acquisition and minimal processing as conducted by Xcalibur Multiphysics (Airborne Survey Contractor). Data were collected on the following 16 rivers: Rivers within the MAP boundary: Black, White, Big Sunflower, Little Sunflower, Ouachita, Tensas, Obion, Saline, Little Red, and Bogue Phalia. Rivers within the Chicot Aquifer extent : Mermentau, Calcasieu, Sabine, Vermillion, Bayou Teche and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers. Where possible, lines were flown along the toe of the levee both on the side adjacent to the river and on the side opposite the river. In addition, where possible, a third line was flown 91m (300 feet) offset from the toe of the levee opposite to the river. Additional processing was done on all levee lines and is described in the data dictionaries and processing step sections of the metadata included in the “Processed Data” and “Resistivity Models” child items of this data release. Seven gridded surveys were collected also: Four grids at different resolutions were collected over gravel bars within the Mississippi River 250 m Line Spacing Prairie Point Island 63 Crumrod 100 m Line Spacing White River 23 line-km at a 100 m line spacing over a property near Minter City, Mississippi (referred to as the Melton grid). 268 line-km at a 500 m spacing over a series of the drill core locations near Paragould, AR. Referred to in this release as the AR OSL grid. 100 line-km at variable spacings over Raccourci Old River, a relic oxbow near Batchelor, LA. Referred to in this release as the Raccourci grid. A dataset collected on small levees near Greenville, Mississippi, in March 2018 is also included in this data release. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This dataset was collected as an evaluation of the technical approach used on the more comprehensive surveys in the MAP and Chicot Aquifer extents. This dataset contains AEM data only (magnetic and radiometric data were not collected). Additional detail on flight line numbers and citations for the various methods used in the collection and processing of the radiometric data is included in the supplemental section.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This data release includes laterally-constrained inverted depth sections along all flight lines from the AEM data. Digital data of the laterally constrained inversions are provided and fields are defined in the data dictionary https://www.sciencebase.gov/catalog/item/5d76ba5ce4b0c4f70d01ff94.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This data release includes laterally-constrained inverted depth sections along all flight lines from the AEM data. Digital data of the laterally constrained inversions are provided and fields are defined in the data dictionary https://www.sciencebase.gov/catalog/item/5d76ba5ce4b0c4f70d01ff94.

Airborne electromagnetic (AEM), magnetic, and radiometric data were acquired May 25 through August 7, 2021 along 10,706 line-kilometers (line-km) over the Mississippi Alluvial Plain (MAP). Data were acquired by Xcalibur Multiphysics with three different helicopter-borne sensors: the Xcalibur Multiphysics 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. Sixteen rivers were surveyed along their center axes, covering 3,467 line-km. Ten rivers are within the surficial Mississippi River Alluvial aquifer boundary: Black River, White River, Big Sunflower River, Little Sunflower River, Ouachita River, Tensas River, Obion River, Saline River, Little Red River, and Bogue Phalia. Six rivers are within the Chicot aquifer boundary: Vermillion River, Bayou Teche, Mermentau River, Calcasieu River, Sabine River, and Bayou Lacassine. Select levee reaches were surveyed along the Mississippi and Arkansas Rivers along the riverside toe, landside toe, and 91m landward offset from the landside toe for a total of 5,896 line-km. Four grids were flown over gravel bars in the Mississippi River: Prairie Point block, Island 63 block, Crumrod block, White River block, and three short segments along the Mississippi River targeting gravel bars. Three additional grids were flown: (1) Melton site in Mississippi with 100-m spaced north-south flight lines for a total of 23 line-km, (2) optically stimulated luminescence (OSL) core study site in Arkansas with 500m east-west line spacing for a total of 268 line-km, and (3) Raccourci Lake in Louisiana with variable flight lines for a total of 100 line-km. Additional detail on flight line numbers is included in the supplemental section. Also included is a small levee dataset acquired in March 2018 near Greenville, Mississippi during the Shellmound AEM survey https://www.sciencebase.gov/catalog/item/5c9e6c42e4b0b8a7f62f5da6. This dataset does not contain magnetic and radiometric data. The survey includes four lines parallel to and over the levee for a total of 27 line-km. This data release includes laterally-constrained inverted depth sections along all flight lines from the AEM data. Digital data of the laterally constrained inversions are provided and fields are defined in the data dictionary https://www.sciencebase.gov/catalog/item/5d76ba5ce4b0c4f70d01ff94.