South Australia
north of Roxby Downs
Lake Eyre is the lowest point in Australia, at approximately 15 m (49 ft) (AHD) below sea level, and, on the rare occasions that it fills, the largest lake in Australia. It is the focal point of the vast Lake Eyre Basin and is found some 700km north of Adelaide.
The lake was named after Edward 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.
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.
The Lake Eyre Basin has a drainage basin that covers one-sixth of all Australia. It is one of the largest internal drainage systems in the world, and covers roughly 1.2 million square kilometres, including much of inland Queensland, large portions of South Australia and the Northern Territory, and a part of western New South Wales.
All the riverbeds in this vast, mostly flat, arid and semi-arid area lead inland (not towards the sea) and on those fairly rare occasions when there is sufficient rainfall to make the rivers flow at all, they flow towards Lake Eyre in central South Australia.
Lake Eyre itself lies 20 metres below sea level, and usually contains only salt. In flood years it fills and for a short time undergoes a period of rapid growth and fertility: long-dormant marine creatures multiply and large flocks of waterfowl arrive to feed and raise their young before the waters evaporate once more.
None of the creeks and rivers in the Lake Eyre Basin are permanent: they flow only after heavy rain–a rare to very rare event in the arid interior of Australia. Average annual rainfall in the area surrounding Lake Eyre is 125mm (5 inches), and the pan evaporation rate 3.5 metres (about 11 feet). Annualised average figures are misleading: since 1885 average rainfall over the 1,100,000 square kilometres of the Lake Eyre Basin has ranged from about 45 millimetres (less than 2 inches) in 1928 to over 760 millimetres (30 inches) in 1974. Most of the water reaching Lake Eyre comes from the river systems of semi-arid inland Queensland, roughly 1000 kilometres to the north.
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For the next epic journey, if they are looking for someone to drive the air conditioned support vehicle, be sure to tell them not to give me a ring.
. there are areas where even a Quad cant go at times
