The Western Plateau is Australia's largest drainage division[1] and is composed predominantly of the remains of the ancient rock shield of Gondwana. It covers two thirds of the continent; 2,700,000 square kilometres (1,000,000 sq mi) of arid land, including large parts of Western Australia, South Australia, and the Northern Territory. For comparison, it is roughly the same size as the whole of continental Europe from Poland west to Portugal.
Rain rarely falls in this region and aside from a handful of permanent waterholes, surface water is absent at all times except after heavy rain. Most of the territory is flat sandy or stony desert with a sparse covering of shrubs or tussock grasses.[citation needed] Average rainfall varies from one area to another and is quoted at 189 millimetres (7.4 in) to 398 millimetres (15.7 in) per year, but is highly unpredictable.[1]
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edit- ^ a b "Australian Catchment, River and Estuary Assessment 2002". Australian Natural Resources Atlas (ANRA). Archived from the original on 22 August 2008.