Correlating Helicopter EM and Borings for Levee Evaluation Studies in California

On-going studies of the flood-control levees in the Sacramento valley, California have included airborne EM and magnetic surveys, DC resistivity surveys, cone penetrometer testing and reverse-circulation borings. This paper reports on how airborne EM is being used to provide a regional overview of the levee foundations, tie-together and extend the CPT and boring information, as well as providing mapping of the horizontal extent of sand channels.