Incorporating uncertainty into groundwater salinity mapping using AEM data

Airborne electromagnetic surveys provide spatially extensive resistivity information that can be useful for groundwater salinity mapping; however, the transformation from geophysical data to salinity interpretations carries uncertainty. We compare two quantitative approaches to salinity mapping recently applied to address water resource management objectives: the location of the depth to the freshwater-brine interface at Paradox Valley, Colorado, and 3D categorical mapping of fresh, brackish, and saline groundwater near oil and gas fields of the San Joaquin Valley, California. These different approaches were driven by a combination of the availability of water quality observations, the hydrogeologic setting, and study objectives.