Streambed Induction Logs: An Airborne Approach to Identifying Salinity Sources and Quantifying Salinity Loads

Wedelineated natural and oil-field salinity sources that degrade water qualityin the upper Colorado River (west Texas) andPetronila Creek (Texascoast) by combining multifrequency airborne EM measurements of apparent groundconductivity with chemical analyses of surface water at key streamlocations. To reduce the cost of high-resolution airborne surveying oversuch large areas, we first flew along the stream axesand then examined preliminary results in the field to identifylikely salinized stream segments. We then flew more detailed surveysover these areas rather than over the entire basin. Stream-axisEM data also helped identify water-sampling locations upstream and downstreamfrom each salinized segment. We used these data to calculatesalinity [...]