CGG Geophysical Survey Aircraft like this one will be used in the project. Photo: Geoscience Australia, XCALIBUR SMART MAPPING
Look to the skies over the next couple of months and you might just see some cutting-edge science in action, as geologists chase groundwater and mineral deposits across northern Victoria.
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Geoscience Australia, in collaboration with the Geological Survey of Victoria, is completing airborne electromagnetic surveys, or AEMs, across much of the continent.
The northern Victorian patch gets its turn from June through to November.
The surveys measure conductivity by sending and receiving electromagnetic signals down about 250m into the ground, from an aircraft.
When the signals return, they paint a picture of the ground’s make-up.
The surveys are looking for large variations in returned signals, caused by the presence of groundwater and minerals.
Light aircraft are equipped with electromagnetic survey equipment, and will fly about 120m above the ground. Not to scale. AI-generated using ChatGPT.
When conductivity is high, it indicates the presence of saline material, such as rock layers holding salty water, clays or minerals. When conductivity readings are low, it indicates dry rocks, sands or fresh water deposits.
For farmers, that water data can be a useful tool. Groundwater is typically stored in aquifers, porous layers of sand, gravel or fractured rock where there is space for water to sit.
Denser layers called aquitards, such as silt and clay, sit above or below and can block or slow the flow of water between aquifers.
Knowing where these layers sit, how deep they run and whether they hold fresh or saline water helps farmers and water managers understand how to place and use their bores.
Goulburn-Murray Water reports that northern Victoria currently has 2800 customers licensed to take and use groundwater bores. The actual number of bores may be much higher, with that not accounting for private domestic bores and customers who host several bores under the one license.
The data will also help identify where aquifers are recharged and where groundwater instead feeds back into rivers, wetlands and springs.
That connection between surface and groundwater is increasingly important for irrigators and catchment managers planning for drought resilience, particularly as demand on the Murray-Darling system continues to be tightly managed.
Geoscience Australia geophysical project officer Wayne Cook said the data would be interpreted to enhance knowledge of the region's geology and its natural resource potential, covering minerals, energy and groundwater, and could also inform land management decisions.
"AEM surveys provide data to characterise and map the underlying geology of the area, including rock layers and the presence and quality of groundwater," Mr Cook said.
A fixed-wing aircraft towing equipment below it will fly approximately 120m above the ground, as low as it can go without compromising data quality.
The plane will make a single pass along survey lines spaced 2km, 5km and 10km apart.
Geoscience Australia is conducting airborne electromagnetic surveys across northern Victoria, mapping the ground beneath our feet. Source: Geoscience Australia
Mr Cook said livestock were considered during the planning process, with more than 650,000km of surveys flown nationally to date.
"Given that the aircraft passes by quickly, it has been Geoscience Australia's experience that livestock are usually not bothered," he said.
Livestock breeding and birthing periods are factored into the consultation process before flights take place.
The signal has similar output to powerlines or a mobile phone, with Mr Cook saying he was not aware of any farm equipment, including electric or virtual fencing and irrigation systems, being affected by surveys.
Once complete, the data will be layered with existing geological, satellite and groundwater information to build a clearer three-dimensional picture of what lies beneath the region.
That combined picture is intended to help irrigators and farmers make better-informed decisions about bore placement, irrigation planning and land management, while supporting broader regional water allocation and drought-preparedness planning.
Farmers or residents with questions or concerns while the survey is under way can contact Geoscience Australia by calling 1800 800 173, or emailing geophysical.surveys@ga.gov.au
Data from the survey, along with associated interpretations and reports, will be made publicly available by Geoscience Australia and the Geological Survey of Victoria once complete.
