Airborne geophysical surveys ? applications in land management

Abstract

Following clearing of native vegetation for agriculture, large parts of agricultural areas in Western Australia have become affected by soil salinity. The decrease in water discharge via transpiration of vegetation has caused water tables to rise and mobilise salts stored in the weathered profile. Investigations of the surface have failed to explain the causes of the patterns of saline outbreaks. Street and Engel (1990) showed that ground geophysical methods have application in detecting hydrological controls within the landscape. This paper reports on the research carried out by World Geoscience Corporation in conjunction with the WA Department of Agriculture into the application of airborne magnetic and electromagnetic surveys for soil salinity. The East Yornaning Catchment in Western Australia has been studied in considerable detail using airborne geophysics followed by ground investigations. The geophysics shows that on a broad scale salt storage within the landscape is controlled by topography and lateral changes in hydraulic conductivity due to weathered dolerite dykes. The knowledge of and controls on the salt storage distribution is essential in good land management planning to achieve sustainable agricultural practices.