Identifying Ground-water Resources and Intrabasinal Faults in the Hueco Bolson, West Texas, using Airborne Electromagnetic Induction and Magnetic-field Data

Abstract

We conducted a high-resolution airborne geophysical survey at the eastern margin of the basin-and-range province of the southwestern U.S. to examine the hydrostratigraphy of the Hueco Bolson and identify possible ground-water resources in this arid area. The survey, flown in 2001 over a 372-km2 area east of El Paso, Texas, acquired time-domain electromagnetic induction (TDEM) and magnetic field data. These data were used to map conductivity trends to depths of at least 200 m that are related to lateral and vertical changes in lithology, water content, water chemistry (EM data), basin geometry, and the location of intrabasinal faults (magnetic data). Pre-survey, ground-based TDEM soundings established the achievable exploration depths and demonstrated that the relatively deep groundwater (80 to 120 m) significantly influenced the transient signal and was within the exploration depth of the airborne system. Airborne EM and magnetic field data identified intrabasinal faults that influence basin-fill deposition. Conductivity-depth slices constructed from airborne TDEM data allowed lateral variations in water quality and lithology to be mapped that helped predict ground-water resource quality within these fault-bounded basins filled with alluvial, lacustrine, and eolian sediments.