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MDBC Airborne Geophysics Project: Final Report Billabong Creek August 2003
Executive Summary
The Murray Darling Basin Commission (MDBC) Airborne Geophysics Project was set up to demonstrate the usefulness of airborne geophysics for the management of salinity at a catchment scale. This was to be achieved by providing substantial airborne geophysical coverage, and on-ground calibration of the airborne data, for areas with perceived salinity problems.
Prior to the adoption of this MDBC program several recent studies had identified the increasing potential for the latest generation of airborne geophysics data to provide a basis for improved mapping of sub-surface salt. However it was acknowledged that a more integrated, multidisciplinary interpretation approach combining ground observations and expert hydrogeological interpretations was essential. This new generation mapping and interpretation offers the potential for improved prediction of future salt mobilisation.
It was also intended to support the MDBC / CSIRO Heartlands Program, which was established to develop sustainable farming systems for salt-affected land. Therefore, two of the key catchments of the Heartlands Program were selected:
- The upper Billabong Creek catchment around Culcairn in the River Murray catchment of Southern NSW, some 40km east-west and 30km north-south, bounded by latitudes 35° 36’ and 35° 49’ S and longitudes 146° 36’ and 147° 5’ E
- The Honeysuckle Creek catchment of the Victorian Broken River catchment, SE of Shepparton: some 45 km east-west and 35km north-south, bounded by latitudes 36° 25-45’ S and longitudes 145° 23-53’ E. The survey area included the Sheep Pen Creek Catchment already chosen by CSIRO Heartlands, but was extended westwards to include areas where existing regional magnetics data showed a distinctive pattern of prior streams that might be directing groundwater and, hence, salt movement. Also included was part of the Strathbogie foothills where salt outbreaks had already been mapped.
The airborne geophysics products developed were airborne electromagnetics, displayed as conductivity depth images (CDIs) and layered earth inversions; magnetics; and gamma-radiometrics. The Bureau of Rural Sciences (BRS) was also contracted to undertake a drilling program in the Billabong Creek catchment to validate the airborne data.
Subsequently, the Goulburn-Broken CMA and Goulburn-Murray Water contracted the BRS to undertake a drilling program at Honeysuckle Creek.
The Victorian Geological Survey then used the geophysical logs obtained through this drilling program to re-calibrate the CDI’s as a separate initiative, on their part, to this project.
The airborne data are lodged with the MDBC and also Geoscience Australia. The bore data are lodged with the MDBC and also BRS.