Cooper Creek - Course

Course

It rises west of the Great Dividing Range on low ground as two central Queensland rivers, the Thomson between Longreach and Charters Towers, and the Barcoo in the area around Barcaldine, about 500 kilometres (310 mi) inland from Rockhampton.

Cooper Creek spreads out into a vast area of anastomosing ephemeral channels, making its way roughly south into the far south-west corner of Queensland before turning due west into South Australia towards Lake Eyre. In most years, it is absorbed into the earth, goes to fill channels and the many permanent waterholes and lakes such as Lake Yamma Yamma, or simply evaporates without reaching Lake Eyre.

In very wet years, however, it manages to flood the entire Channel Country and reaches Lake Eyre after flowing through the dry areas of Strzelecki Desert, Sturt Stony Desert and the Tirari Desert. Studies have clearly shown that, although with a mean annual flow of around 2.3 cubic kilometres (0.55 cu mi) (ranging at Barcoo from an estimated 0.02 km3 or 16,000 acre·ft in 1902 to an estimated 12 km3 or 2.9 cu mi in 1950) the Cooper carries twice as much runoff as the Diamantina and three times as much as the Georgina, over the past ten thousand years it has reached Lake Eyre much less frequently than those rivers. This is because much more water is absorbed along its course than with the Diamantina or Georgina, but could possibly be also because centennial or multicentennial wet and dry cycles in those basins causing them to regularly reach the lake during wet periods (there is some evidence from terraces around Lake Eyre that this occurred during the Medieval Warm Period). During a flooding event the river upstream of Windorah may be as wide as 40 kilometres (25 mi).