An electromagnetic induction technique for reconnaissance surveys of soil salinity hazards

Abstract

An assessment has been made of an electromagnetic induction (EM) technique for reconnaissance surveys of soil salinity. The instrument used provides values of apparent electrical conductivity to depths ranging from 7.5 to 60 m. A comparison of EM values with actual profile salinities at 19 sites of widely differing geological and geomorphic origin showed that approximately 65% of the variance of EM values is explained in terms of salinity alone. An area of 10000 km2 in the mid-Lachlan River Valley of New South Wales was surveyed with a grid spacing of approximately 5 km at a rate of 30-40 sites per day. This permitted the definition of areas of high subsoil apparent conductivity and hence, by inference, of high soil salinity. The EM technique was demonstrated to have a potential for providing a significant contribution to land use planning at both a regional and local scale, by defining areas of possible salinity hazard.