Airborne electromagnetic (AEM) and magnetic survey data were collected during October 2016 along 1,443 line kilometers in the southwestern San Joaquin Valley near Lost Hills, California. These data were collected in support of groundwater salinity mapping and hydrogeologic framework development as part of the U.S. Geological Survey California Oil, Gas, and Groundwater program and the California State Water Resources Control Board’s Program of Regional Monitoring of Water Quality in Areas of Oil and Gas Production. Deterministic laterally constrained inversions of the processed airborne electromagnetic data (https://www.sciencebase.gov/catalog/item/5d60373ae4b01d82ce9854ec) were developed using the AarhusINV code (Auken et al. 2014, https://doi.org/10.1071/EG13097) implemented in Aarhus Workbench software (v. 5.6.3.0, 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 smooth 30-layer fixed-depth inversion model was developed with layer top depths ranging between 3 and 400 meters and layer thickness increasing with depth (see model data for exact thicknesses). Relatively weak vertical and lateral constraints on resistivity were used with values of 2.5 and 2.0, respectively. A 30 ohm-meter homogenous half-space starting model was used. Sensor altitude was treated as a free parameter after the 5th iteration. The final model parameters described above were selected because they best represented the physical understanding of the system and minimized data misfit.
The data provided include laterally-constrained 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