An Airborne Electromagnetic (Em) Survey Used To Map The Upper San Pedro River Aquifer, Near Fort Huachuca In Southeastern Arizona

An airborne EM survey using a 3-component, 20-channel GEOTEM system with an<br>additional airborne magnetic channel was flown over Fort Huachuca and the area north and east<br>as far as the San Pedro River, southeastern Arizona. Inversions of the EM data, so-called<br>Conductivity-Depth Transforms (CDTs), provide remarkable information on the upper San Pedro<br>River aquifer down to 400 meter depths in some cases; results agree with limited well-control.<br>Depths derived from the magnetic data set, when inverted using an Euler transform, agree well<br>with a map of the basement derived earlier from gravity data. Together, the complete data set<br>allows us to map the Upper San Pedro River aquifer in a region where there is dispute over<br>allocation of scarce water resources and the San Pedro Riparian Conservation Area.