Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Overview - New South Wales

Location map of Great Artesian Basin - Central

Groundwater Management Unit: Great Artesian Basin - Central

Introduction

The Great Artesian Basin covers a large part of Queensland, New South Wales, South Australia, and the Northern Territory, with the largest portion being in Queensland. Water from its sandstone aquifers is effectively the sole source of water for the pastoral industry over much of this area, and is also an important source of water for a number of town water supplies, and for some mining enterprises. The artesian nature of the aquifers, which causes water to flow to the surface without the need for pumping, makes it especially useful and this factor has enabled the distribution of water through an extensive network of open channels (bore drains) for stock use over a wide area from a single bore. Much of the water is quite hot, and this factor has led to the use of some of the water for use in public baths, as at Moree. The estimated total current abstraction from the Basin is about 570 000 ML/y. The efficiency of use of this water is very low, however, because of leaking bores and inefficient distribution through open drains to stock watering points. The proportion of the abstracted water which is not productively used is probably near 90%.

Groundwater management is the responsibility of each State or Territory, but the groundwater system is continuous across State borders and there is a need for some commonality of approach. This is now being provided by the Great Artesian Basin Consultative Council, which is a body representative of government, industry, conservation and community interests. The Council has published a Resource Study (GABCC 1998a), which is a compilation of the most up to date information available, and has released a draft Strategic management Plan (GABCC 1998b).

The GABCC has defined 23 Hydrologic Zones within the Basin, and they have been adopted as the basis for Groundwater Management Units for the purpose of the Audit. Those in NSW are the Southern Recharge Zone (along the south east margin of the Basin), Surat NSW (that part of the Surat sub basin which is in NSW), Warrego NSW (adjacent to and continuous with the Warrego Queensland zone), and Central NSW (in far north- west NSW and continuous with Queensland and South Australian parts) which is part of the Central Zone.

In NSW, a joint community/government approach to management of the groundwater resources of the Basin has been adopted, and the vehicle for this is the NSW Great Artesian Basin Advisory Committee. It has representation from Local, State and Federal government agencies, user groups, and the NSW Nature Conservation Council. The Committee has provided some basic data about the NSW part of the Basin.

The total area of the Basin in NSW is 207 000 km2. There are 718 bores still flowing, and the total abstraction is approximately 135 000 ML/y. The volume of water entering the NSW part of the Basin is approximately 290000 ML/y, of which recharge from rainfall is about 195000 ML/y and underflow through the aquifer system from Queensalnd is estimated to be about 95000 ML/y. The sustainable yield for the NSW part of the Basin is estimated to be in the range 85000 110000 ML/y. Further Community debate on the value of restoring pressure to the basin coupled with landholder/government financial capability to cap and pipe free flowing bores will ultimately decide on the sustainable yield that the basin will be managed to.

The Central (NSW) Groundwater Management Unit (GMU) has an area of about 51200 sq km which is 2.8% of the total GAB area. It is in the southern region of the GAB and extends for about 240 km east from the South Australian border and about 240 km south from the Queensland border , to the boundary of the GAB. The town of Tibooburra lies within the Central (NSW) zone.

Ground level ranges from zero to 200 m AHD in most of the area but there are small areas in the central part where ground level reaches an elevation of 300 m AHD.

Rainfall in the Central (NSW) zone varies from about 150 mm/yr in the west to 200 mm/yr in the east. Evaporation generally exceeds average annual rainfall by 2400 to 3200 mm/yr.

Land tenure is mainly leasehold in this zone, with scattered areas of Nature Conservation Reserve and other Crown Land. Varieties of shrubland dominate the vegetation within with small scattered areas of woodland and dense sown pasture. The dominant land use is pastoral, for sheep and cattle.

Vital Statistics:

Area: 51,200 Km2
Total water allocated: no data
Total water consumed: 6,580 ML/yr
Average salinity: 3,051 mg/l
Sustainable yield: 5,750 ML/yr
Depth to top of aquifier: 440 m

Further Information

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