FLOODS OF LAKE EYRE
Lake Eyre Geography
Lake Eyre North occupies an area of 8 430 km² and can contain 27.7 km³ of water at - 9.5 m ahd and an average depth of 3.3 m. The deepest region of Lake Eyre North is the eastern part of Belt Bay in which bottom levels just deeper than —15.2 m ahd were found - the lowest point on the Australian continent. The floor of the Lake is very flat with bottom slopes in the order of 2 x 10-5, so the definition of the exact location is rather difficult. The deepest points of Madigan Gulf and Jackboot Bay are —15.2 m and —15.0 m ahd respectively.
Lake Eyre South occupies an area of 1 260 km² and can store 2.4 km³ of water at -9.5 m ahd and an average depth of 1.9 m. The deepest region, reaching -13.2 m ahd, is located in a long trough offshore from the southern coastline.
The Goyder Channel, which connects Lake Eyre North and Lake Eyre South, has a length of 15 km and a width varying between 200 and 1 500 m. The bottom elevation of the channel changes after every major event. Allan et al. (1986) note that the sill level has been reduced from -10.1 m ahd (Bonython, 1961), through -10.6 m ahd (Bye et al., 1978), to -11.0 m ahd in 1984.
Diamantina River rises in Kirbys Nob, east of Selwyn in Queensland. Through the majority of the 720 km distance to Birdsville it runs as a braided channel with a mean slope of 2.7 x 10-4. At Birdsville, where the catchment area is 115 000 km², there is only one site along the central reach where the Diamantina is sufficiently confined for accurate measurement.