Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Overview - New South Wales

Location map of Great Artesian Basin - Southern Recharge - NSW

Groundwater Management Unit: Great Artesian Basin - Southern Recharge - NSW

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 southeast 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 Queensland 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 Southern Recharge Groundwater Management Unit (GMU) has an area of approximately 16 000 sq km, which accounts for 2% of the total GAB area. It is the marginal zone of the Basin and extends from the QLD / NSW border in the north to Narromine in the southwest, and ranges from 50 to 100 km in width. The natural surface level ranges from 100 m to 800 m AHD but is mostly between 300 and 500 m AHD.

Rainfall in the Southern Recharge zone varies from 400 to 800 mm/yr. Approximately 50% of rainfall occurs in the months November to March. Average annual evaporation may exceed average annual rainfall by up to 1800 mm/yr. Woodlands (open and closed) are the major vegetation types present, with some tussock grassland or sedgeland.

Agricultural land uses are dominant in the area, but sheep and cattle grazing are also important. Most of the land is held under freehold tenure, but there are some minor Forest Reserves.

Vital Statistics:

Area: 32,960 Km2
Total water allocated: no data
Total water consumed: 11,580 ML/yr
Average salinity: 1,000 mg/l
Sustainable yield: 10,100 ML/yr
Depth to top of aquifier: 180 m

Further Information

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