Lake Eyre Basin Sign, Birdsville Track. Photo: M Turner
At 1.2 million square kilometers, the Lake Eyre Basin covers almost one-sixth of Australia and is one of the world's largest internally draining river systems. The Basin includes large parts of South Australia, the Northern Territory and Queensland, as well as a small part of western New South Wales. The area supports a range of nationally important natural, social and economic values and about 60,000 people live and work in the Basin.
Within this huge Basin, at Australia's lowest point (15.2 metres below sea level), lies Kati Thanda - Lake Eyre, the fourth largest terminal lake in the world. However, Kati Thanda - Lake Eyre usually contains little or no water, as its catchment is wholly within the arid and semi-arid deserts of Central Australia.
Even though the Lake Eyre Basin contains some of the world's last unregulated wild river systems, the arid climate means that these are not typical rivers - all the creeks and rivers are ephemeral, running for short periods following rain, but dry for the long periods between rains. And in Australian deserts, the sporadic rainfall events are even more unpredictable and more variable than those in other arid parts of the world.
Map of the Lake Eyre Basin Catchment Area
When these rivers do flow, they reveal further differences. Unlike temperate rivers, whose volume increases downstream as tributaries contribute more water, the volume of flow
decreases downstream due to natural diversion across the landscape. On the way to Kati Thanda - Lake Eyre, water travels through a huge dispersal system of braided channels, floodplains, waterholes and wetlands. These natural diversions increase the already high losses to infiltration and evaporation, and mean that most of the water falling in the catchment never gets to Kati Thanda - Lake Eyre.
The landscape of the Basin is typified by low relief, with the few higher areas found on the western and southern boundaries (the MacDonnell and Flinders Ranges respectively). The pervasive flatness underlies the way in which water spreads across the landscape, greatly increasing the amount which soaks into the ground or evaporates. This in turn contributes to another characteristic of the Basin - the saline nature of the landscape. The constantly high evaporation rate (2.5m a year) leads to gradual but relentless build up of salt that accumulates in the soil, only to be released again at the next rain, and concentrated even further in the ensuing dry times.
The ecosystems of the Basin are varied, but given the arid climate, the ones that make the region exceptional are those associated with the ephemeral wetlands and the many large permanent waterholes in the system. There are many natural areas of high conservation importance, including internationally recognised wetlands, as well as extensive grasslands and remarkable dune fields. Some specific examples include the Coongie Lakes (Ramsar listed), Astrebla Downs National Park and Munga-Thirri National Park.
Lake Eyre Basin Aquatic Ecosystems Map
After rain, extraordinarily large flocks of water birds gather in the Basin to breed, attracted by the masses of aquatic invertebrates in the flooded waterways. Abundant and varied fish populations seem to come from nowhere and the calls of the most diverse frog community in Central Australia are well evident. Mound springs, occurring at points of natural water seepage from the Great Artesian Basin, support a number of rare species, many found only in association with these unusual water bodies. Several regions contain rare plants, the snake fauna is unusually diverse, and some small mammals, rare or extinct in the rest of Australia, still occur in the Basin (e.g. the Kowari).
Several large, and many small towns, as well as Aboriginal communities, are scattered across the region. Land use includes (but is not limited to) grazing, mining, oil and gas exploration and production, tourism, conservation and Aboriginal activities. The area is culturally significant and contains a wealth of Aboriginal and non-Aboriginal history.
The Lake Eyre Basin is rich in environmental, economic and cultural assets that are important for people both within and outside the Basin, and the sustainable management of these assets is in the local, regional, national and international interest. Luckily, the Lake Eyre Basin is still relatively pristine, with most of its rivers unregulated. To increase the chances that future generations will be able to use and enjoy this special place, we need to apply the lessons learned from our mistakes in Australia's other great surface water basin, the Murray-Darling. Changes to the natural flows in that system have led to environmental damage and mounting costs. All community sectors across the Lake Eyre Basin, scientists and governments are involved in a collaborative effort (principally under the
Lake Eyre Basin Intergovernmental Agreement) to ensure that the health of the unique river systems of the Basin can be maintained.
A short slide presentation on the Lake Eyre Basin is available for viewing.
- The Arabana people, traditional owners of the Lake Eyre region, call the lake "Kati Thanda", a term now officially recognised in the dual place name "Kati Thanda - Lake Eyre".
- Kati Thanda - Lake Eyre is a 'wetland' in the desert.
- Some wetlands in the Basin support fish known to reach 80 years old.
- The Lake Eyre Basin is more than five times the size of Victoria.
- On average, only a tiny fraction of the rain that falls in the Basin will flow all the way to Kati Thanda - Lake Eyre.
- The channel country and waterholes are home to millions of breeding birds after rain.
- At 9,700km2, Kati Thanda - Lake Eyre is the fourth largest terminal lake in the world.
- Kati Thanda - Lake Eyre lies in the most arid part of Australia, with an average annual rainfall of less than 125mm and an evaporation rate of 2.5m.
- The Lake Eyre Basin Drainage Division is the only Australian drainage division that doesn't reach the coast.