Airborne electromagnetic and magnetic survey, western Hualapai Indian Reservation near Grand Canyon West and Peach Springs, Arizona, 2018: Inverted resistivity models

Airborne electromagnetic (AEM) and magnetic survey data were collected during March 2018 along 1,637 line kilometers over the western Hualapai Indian Reservation and surrounding areas. The survey was conducted as part of a study of the groundwater resources of the Truxton basin and Hualapai Plateau. The survey was designed to improve the understanding of the geometry of major hydrostratigraphic contacts of the study area.
Deterministic laterally constrained inversion of the processed AEM data (https://www.sciencebase.gov/catalog/item/5d606016e4b01d82ce98558e) was conducted using the AarhusINV code (Auken and others, 2014) implemented in Aarhus Workbench software (Aarhus Geosoftware, Aarhus, Denmark). Inversion parameters were selected by running a series of test models with varying starting model resistivity values, layer discretization, horizontal/lateral constraints, and other inversion parameters. A 32-layer fixed-depth smooth inversion model was developed with layer top depths ranging between 5 and 700 meters and layer thickness increasing with depth Inversions were run with vertical and lateral constraints of values of 4.0 and 1.6, respectively, and a 300 ohm-meter homogenous half-space starting model. Sensor altitude was treated as a free parameter after the 7th iteration. Depth of investigation was calculated with a minimum and maximum depth of 5 and 800 meters. The data provided include inverted resistivity models and plotted depth sections along all flight lines. Digital data are described in the data dictionary, additional details regarding data inversion are described in the metadata processing steps.