Warrego River and Great Artesian Basin, Australia
The Warrego River is situated in south west Queensland and north west New South Wales, Australia.
Most of the basin of the Warrego is too dry for cropping and has a very erratic rainfall of between 350 and 500 millimetres (14 and 20 inches). It is covered with a natural vegetation of grassland of more fertile clay soils, and saltbush shrubland on less fertile red earths, all visible to the right.
The predominant land use is low-intensity grazing of sheep and cattle: the river’s flow is much too erratic to permit of irrigated cropping.
The Warrego is essentially an ephemeral stream: it is not unknown for years to pass without any flow in the basin and substantial amounts of water reach the Darling River only in wet years almost always associated with La Niña events.
The Warrego River is part of the the Great Artesian Basin, which provides the only reliable source of water through much of inland Australia.
The basin is the largest and deepest artesian basin in the world, covering a total of 1,711,000 square km. It underlies 23% of the continent, including most of Queensland, the south-east corner of the Northern Territory, the north-east part of South Australia, and northern New South Wales.
The basin is 3000 metres (10,000 ft) deep in places and is estimated to contain 64,900 cubic kilometres of groundwater.