Eyre, Lake

Lake Eyre
Composite Landsat 7 satellite image using shortwave infrared, near-infrared, and blue wavelengths
Location	northern South Australia
Coordinates	28°22′S 137°22′E / 28.367°S 137.367°E / -28.367; 137.367Coordinates: 28°22′S 137°22′E / 28.367°S 137.367°E / -28.367; 137.367
Lake type	endorheic
Primary outflows	evaporation
Basin countries	Australia
Surface area	9500 km² (max)
Average depth	1.5 m (every 3 years), 4 m (every decade)
Surface elevation	−15 m (−49 ft)

Lake Eyre (pronounced "air") is the lowest point in Australia, at approximately 15 m (49 ft) (AHD) below sea level,^{[citation needed]} and, on the rare occasions that it fills, it is the largest lake in Australia. It is the focal point of the vast Lake Eyre Basin and is found some 700 km north of Adelaide.

Geography

The lake was named after Edward John Eyre who was the first European to sight it in 1840. The lake is located in the deserts of central Australia, in northern South Australia. The Eyre Basin is a large endorheic system surrounding the lakebed, the lowest part of which is filled with the characteristic playa salt pan caused by the seasonal expansion and subsequent evaporation of the trapped waters. Even in the dry season there is usually some water remaining in Lake Eyre, usually collecting in a number of smaller sub-lakes on the playa.

During the rainy season the rivers from the northeast (in outback Queensland) flow towards the lake through the Channel Country. The amount of water from the monsoon determines whether water will reach the lake and if it does, how deep the lake will get. In strong La Niña years the lake can fill. Since 1885 this has occurred in 1886/1887, 1889/1890, 1916/1917, 1950, 1955, 1974-1976 ^[1], with the highest flood of 6m in 1974. Local rain can also fill Lake Eyre to 3-4m as occurred in 1984 and 1989. Wave built shingle terraces on the shore suggest that during the Medieval Warm Period and centuries immediately prior Lake Eyre possibly held permanent water at levels above those of 1974. Torrential rain in January 2007 took about six weeks to reach the lake but put only a small amount of water into it.^[2]

When recently flooded the Lake is almost fresh and native fresh water fish, including boney bream (Nematolosa erebi), the Lake Eyre Basin sub-species of golden perch (Macquaria ambigua) and various small hardyhead species (Craterocephalus spp.) can survive in it. The salinity increases as the 450mm salt crust dissolves over a period of six months resulting in a massive fish kill. When over 4m deep the Lake is no more salty than the sea and salinity increases as the water evaporates with saturation occurring at about 500mm depth. The Lake takes on a "pink" hue when saturated due to the presence of beta-carotene pigment caused by the algae Dunaliella salina.

Typically a 1.5 m (5 ft) flood occurs every three years, a 4 m (13 ft) flood every decade, and a fill or near fill four times a century. The water in the lake soon evaporates with a minor and medium flood drying by the end of the following summer.

Lake Eyre South.

Lake Eyre salt crust.

2009

The 2009 Lake Eyre flood peaked at 1.5m deep in late May which is a quarter of its maximum recorded depth of 6m. Nine cubic kilometres of water crossed the Queensland - South Australian border with most of it coming from massive floods in the Georgina River. However the greater proportion soaked into the desert or evaporated en route to the Lake leaving less than one cubic kilometre in the Lake which covered an area of 800 square kilometres or 12% of the Lake. As the flood did not start filling the Lake's deepest point (Belt Bay) until late March little bird life appeared preferring instead to nest in the upper reaches of the Lake Eyre Basin, north of Birdsville, where large lakes appeared in January as a result of monsoonal rain.

Lake Eyre during dry season.

Lake Eyre during rainy season.

Lake Eyre at its fullest in 2009.

Yacht club

The Lake Eyre Yacht Club is a dedicated group of eccentrics 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

It has been a site for various land speed record attempts on its salt flats, especially those by Sir Donald Campbell with the Bluebird-Proteus CN7.

See also

• Lake Eyre Basin
• Pluvial lake
• List of lakes
• List of world's largest lakes

References

External links

• NASA Earth Observatory pages on Lake Eyre: [1], [2]
• Lake Eyre Yacht Club website
• Lake Eyre pelican mystery
• Floods of Lake Eyre - Dr Vincent Kotwicki's site