Ancient groundwater systems of the Great Artesian Basin

21/03/2014

Man using groundwater sampling equipment in the middle of a muddy field

Extraction and measurement
of gases from groundwater
samples collected during a
groundwater chemistry
survey of the Surat and
Bowen basins
in Queensland.

A new groundwater dataset was released today by Geoscience Australia, collected as part of a comprehensive groundwater chemistry survey of the Surat and Bowen basins in Queensland.

The results provide an additional baseline for assessing potential future impacts on groundwater resources within the Great Artesian Basin, from resource uses such as agriculture, geological storage of carbon dioxide, and mineral and hydrocarbon production.

The project leader of the study, Dr Andrew Feitz, explained that this is the first time some of the aquifers have been sampled for certain isotopic data, with initial analysis suggesting that the deeper groundwater in the centre of the Surat Basin may be in the order of one million years old.

One of the primary aquifers targeted during the multi-year survey was the Hutton Sandstone formation in southern Queensland. Prior to this study, very little isotopic data had been collected from groundwater within the Hutton Sandstone despite it being a major aquifer used for agriculture within the Great Artesian Basin.

In addition to analysing groundwater samples, the dataset includes a comprehensive isotopic analysis of water and groundwater gas samples, as well as analysis for trace organic and trace metal contaminants.

The study also investigated a range of new analytical techniques as a first step in determining how useful they could be in detecting potential migration of gases into overlying aquifers. The risk and impact of carbon dioxide migrating from a greenhouse gas storage reservoir into groundwater cannot be objectively assessed without knowledge of the natural baseline characteristics of the groundwater within these systems.

The work was undertaken by Geoscience Australia, the Geological Survey of Queensland and the Queensland Department of Mines and Energy under the National Geoscience Agreement as part of a collaborative effort to characterise the regional groundwater hydrochemistry of the Surat and Bowen basins.

The dataset is now available for download via Geoscience Australia's website.

Further work is currently being undertaken to integrate the data as part of a Hydrogeological and Hydrochemistry Atlas of the Great Artesian Basin, due for release in late 2014.