By Donna Kelly

14 August, 2012 — The ancient, buried river valleys often relied on in regional Australia to supply water to pastoralists, mines, tourist centres and remote communities have been mapped in a massive project to study Australia’s future water supply.

The National Water Commission released its findings on these underground river systems, known as paleovalleys, in its Paleovalley Groundwater Project, a $5 million study, conducted by Geoscience Australia, funded under the Raising National Water Standards Program.

They represent the only viable groundwater resource in many areas with the estimated annual volume of groundwater currently extracted from paleovalleys more than 200 gigalitres in Western Australia, 14 gigalitres in South Australia and eight gigalitres in the Northern Territory.

Geoscience Australia project leader Steven Lewis said paleovalley groundwater resources were essential to sustaining mining operations, horticulture, tourist sites and thousands of bores on pastoral stations.

However, an accurate account of the water recharge processes was critical to inform decisions on how extraction should be handled to ensure sustainability of the resource, he said.

“Prior to this project there was no coordinated investigation at a national-scale to improve our knowledge of paleovalley aquifers. Nor was there a well-defined approach for mapping and characterising paleovalley aquifers as prospective water resource targets,” he said.

A map showing about 200 discrete palaeovalleys in Western Australia, South Australia and the Northern Territory has also been developed.

“Some of these paleovalleys were larger than the Murray-Darling River system, and we have mapped several that began in the Northern Territory and ran westwards until they eventually flowed into the Indian Ocean,” Dr Lewis said.

“In undertaking this work, we also recognised the importance of paleovalleys to the mineral exploration industry, which could utilise naturally occurring groundwater that has up to four times the salinity of sea water.”

Dr Lewis said the National Water Commission was keen for any future decisions regarding water extraction to take into account the principles agreed under the National Water Initiative for the sustainable and economically efficient use of water resources.

Dr Steven Lewis and colleague Dr Pauline English presented their findings at the 34th International Geological Congress in Brisbane on 9 August.