Study to assess water connectivity in the Condamine

Posted 18 January 2014

Associate Professor Bryce Kelly

The project, led by Associate Professor Bryce Kelly from the Connected Water Initiative Research Centre at the University of New South Wales, will assess the extent of hydraulic connectivity between aquifers used for gas production from within the Walloon Coal Measures and aquifers used by farmers in the Condamine Catchment in South-East Queensland.

This will be achieved by examining the chemistry of the groundwater, measuring the concentration of methane in the groundwater and air, mapping the geology of the region in 3D, analysing the historical groundwater level and chemical data sets, and examining pumping impact scenarios.

“We will sample the groundwater from 30 irrigation bores in ‘priority areas’, these will be selected based on their proximity to new CSG production and exploration wells in the Condamine Catchment,” Bryce said. “To quality assure these data we will also sample some bores where CSG producers and government hydrogeologists have already sampled the groundwater.

Quick facts

• As groundwater moves through the aquifers the chemistry is altered by contact with various sediments and rocks.

• By mapping the changes in the chemistry across a catchment, potential pathways of hydraulic connectivity can be mapped.

• By measuring groundwater levels and the chemistry of the groundwater it may be possible to determine where the Surat Basin is hydraulically connected to the water supplies within the Condamine Alluvium, and where there is a potential hydraulic link between the CSG development in the Walloon Coal Measures and the groundwater used for irrigated agriculture.

• Methane concentration can be an early indicator of connectivity between coal seam gas developments and aquifers used as water supplies. There are no extensive baseline measurements of the methane concentration in the groundwater or air in the Condamine Catchment.

“This will allow us to quantify the potential long-term impacts on farmers’ access to good quality groundwater for irrigated agriculture in the Condamine Alluvium.”

CRDC R&D Manager Jane Trindall will oversee the project and says “in the public domain, there is a lack of hydrogeological data to give the community and farmers confidence in our knowledge of baseline conditions and our capacity to quantify potential longterm impacts”.

“One aim of the project is to provide information that can be used to inform the implementation of best management practices as the CSG industry rapidly develops to safeguard water resources critical to the cotton industry,” Jane said.

Bryce will lead the project in collaboration with Professor Euan Nisbet and Dr Dave Lowry from Royal Holloway, University of London, Dr Dioni Cendon based at Australian Nuclear Science and Technology Organisation (ANSTO), and hydrogeologist Mark Hocking.

The Methane Indicator

“Results from coal bed and shale gas production regions in the US show that if a gas production well is poorly constructed then there is a risk of groundwater contamination at a local scale” Bryce said.

This leakage can be detected as an elevated concentration of methane in the groundwater or in the air near the ground surface. However, methane also occurs naturally throughout the landscape. Biological processes in the groundwater and soil produce methane. This subsurface methane is slowly released to the atmosphere.

Therefore, to determine an elevated concentration, the baseline methane concentration must be measured, and currently there are no extensive baseline measurements of the methane concentration in groundwater or air throughout the Condamine Catchment.

Professor Euan Nisbet and Dr Dave Lowry, in association with colleagues from Royal Holloway, will conduct an air quality survey to map the concentration of methane in and around the irrigation districts and CSG production areas. In addition, UNSW researchers will measure the concentration of methane in the groundwater used for irrigation. They will ‘fingerprint’ the potential origin of the methane, by measuring the isotopes of carbon within the methane molecules.

Tracking water

As groundwater moves through aquifers the chemistry is altered by contact with various sediments and rocks. By mapping changes in the major ion chemistry of the groundwater across a catchment, potential pathways of hydraulic connectivity can be mapped. Dr Dioni Cendon will lead a team from ANSTO who will measure the major ion chemistry and the isotopes of carbon, hydrogen and strontium in the groundwater.

“Isotope measurements are used to determine the age of the groundwater and this helps with quantifying transit time,” Bryce said.

Why target this area?

The Surat Basin underlies a highly productive agricultural industry encompassing grazing, dryland broadacre and irrigated farming. A variety of crops are grown, including cotton. All are dependent in one way or another on the quantity and quality of the surface and ground water.

Profile

Associate Professor Bryce Kelly brings extensive knowledge to the new CRDC project. He has a decade of experience working internationally with the oil and gas sector, and over the past decade he has specialised in improving our knowledge of the hydrogeology of the alluvial aquifers throughout the Murray-Darling Basin. Recently he co-authored a background paper on New South Wales Geology: With a Focus on Basins Containing Coal Seam Gas Resources for the Office of the NSW Chief Scientist and Engineer.

Associate Professor Bryce Kelly has a decade of experience working internationally with the oil and gas sector.

Over the past decade CSG exploration and production has expanded rapidly in the Queensland portion of the Surat Basin, targeting the coals within the Walloon Coal Measures. The Walloon Coal Measures is hydraulically connected to the aquifers of the Great Artesian Basin (within the Surat Basin) and in some locations immediately underlies the Condamine Alluvium. This research will improve knowledge about the hydraulic interactions between the Walloon Coal Measures and the aquifers within the Condamine Alluvium.

“Gas production from the Walloon Coal Measures will eventually result in hundreds of thousands of megalitres of groundwater being extracted each year; this will depressurise the groundwater systems in the Walloon Coal Measures and adjacent geological formations,” says Bryce.

“The full extent of the impacts due to this volume of groundwater extraction will take multiple decades to be transmitted throughout the aquifers of the Great Artesian Basin and the Condamine Alluvium.”

Interested in being part of the study?

Cotton growers in the Condamine Catchment in regions adjacent to CSG exploration and production who would like to participate in this study are encouraged to contact Associate Professor Bryce Kelly at bryce.kelly@unsw.edu.au.

This article first appeared in Spotlight Magazine Spring 2013.

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