Lake Eyre (pronounced "air") is the lowest point in Australia, at about 15 m (49 ft) below sea level.[2] When it fills with water, it is the largest lake in Australia, being 144 km (89 mi) long and 77 km (48 mi) wide.[3] It is also in the driest part of Australia, getting only about 100 mm (4 in) of rain each year.[2] It is in the north of South Australia, about 700 km (435 mi) north of Adelaide. The lake was named after the explorer, Edward Eyre, who was the first Europen to see it in 1840. It is the centre of the Lake Eyre National Park.
Geography
Lake Eyre salt crust
Lake Eyre is in the driest desert region of central Australia.[4] It is a large endorheic lake system, which means that the water flows in, but does not flow out. As the water evaporates, the lake dries up leaving a dry salt lake. The lake does not usually completely dry up, there is often water in small areas on the lake surface. The rate that the water dries up is 2.5 m (98 in) per year, that is about 20 times more than the rainfall in the area.[4]
Filling up
During the wet season the rivers from Queensland flow towards the lake through the Channel Country. These rivers drain about one sixth of Australia, an area the size of Spain.[4] How much water reaches the lake depends on how rain falls in Queensland. Since 1885 the lake has filled in 1886/1887, 1889/1890, 1916/1917, 1950, 1955 and 1974-1976.[5] In 1974 Lake Eyre was 6 m (20 ft) deep. Local rain filled Lake Eyre to 3.5 m (11 ft) in 1984 and 1989. Very heavy rain in January 2007 took about six weeks to reach the lake but put only a small amount of water into it.[6] In February 2009, water from flooding rains in Queensland were flowing along the creeks to the lake covering about 40 km per day.[7] The lake fills to about 1.5 m (5 ft) every three years, to 4 m (13 ft), every ten years, and fills up about four times every 100 years.
Drying up
When Lake Eyre is full, the water is almost fresh and native fresh water fish can live in it. The lake becomes saltier as the 450 mm (18 in) salt crust dissolves over six months. This kills millions of fish. When about 4m deep the Lake is as salty as the sea. It becomes more salty as the water evaporates. At about 500mm depth the Lake becomes a "pink" color because of a beta-carotene pigment made by the algae Dunaliella salina.
Early history
Beaches made by wave action suggest that during the Medieval Warm Period Lake Eyre possibly held permanent water at levels above those of 1974.
The local Aboriginal people, the Arabunna people, have stories that explain the creation of Lake Eyre. These stories are part of their sacred traditions, and are only told to initiated people.[8]
Animal and bird life
Fresh water fish found in the full lake include boney bream (Nematolosa erebi), the Lake Eyre Basin sub-species of golden perch (Macquaria ambigua) and various small hardyhead species (Craterocephalus spp). The Lake Eyre hardyhead, can live in water up to 15 times saltier than the ocean.[8]
When there is water more than 8 million birds, from more than 60 different species, flock to the lake. The pelicans are usually the first to arrive, followed by silver gulls, hoary headed grebes, Australasian grebes, cormorants, ducks, banded stilts, kites, falcons and wedge tailed eagles.[4] Scientists still do not know how the birds know when the lake holds water.[1]
There is also a lizard, the Lake Eyre Dragon, Ctenophorus maculosus, that lives in the cool mud below the salt crust of the lake.[1][8]
Yacht club
The Lake Eyre Yacht Club is a small group of people who sail on the lake's floods, including recent trips in 1997, 2000, 2001, 2004, 2007 and 2009. A number of 6 m Trailer Sailers sailed on Lake Eyre in 1975, 1976 and 1984 when the flood depth reached 3–6 m.
Land speed record attempts
Campbell Plaque at Level Post Bay
The salt crust on the lake is not thick and can break like glass under a person's weight. At Level Post Bay, the crust is more than one metre thick, and because of its flat surface it has been the site for various land speed record attempts. In 1964, British driver, Sir Donald Campbell, set a new record of 664 km/h (413 mph), in the Bluebird-Proteus CN7.[4]
↑ 4.04.14.24.34.4Bailey, John (2006). Mr. Stuart's Track: the forgotten life of Australia's greatest explorer. Sydney: MacMillan. pp. 117–120. ISBN9781405037303.
↑Allen, Robert J.; The Australasian Summer Monsoon, Teleconnections, and Flooding in the Lake Eyre Basin; published 1985 by Royal Geographical Society of Australasia, S.A. Branch; ISBN0-909112-09-6
