Georgina River

The Georgina River is the north-westernmost of the three major rivers of the Channel Country in Central West Queensland, that also flows through a portion of the Northern Territory, in central Australia. Part of the Lake Eyre basin, the Georgina flows in extremely wet years into Lake Eyre.

The river is named in honour of Georgina Mildred Kennedy, the daughter of Queensland governor Arthur Kennedy. The river was originally called the Herbert River before being given its current name in 1890 to avoid confusion with the other river in Queensland that bears that name.

With its headwaters rising in the Barkly Tableland, north of Camooweal in Queensland, and in the extreme east of the Northern Territory beyond Tennant Creek and to the south draining the northern slopes of the Macdonnell Ranges, the Georgina is formed from several smaller streams over a wide area of north-western Queensland and the eastern Northern Territory. From source to mouth, the Georgina is joined by more than 35 tributaries including the Buckley, Templeton, Burke, Hamilton, Herbert, Ranken, and Sandover rivers; and flows through 26 billabongs. As the Georgina flows south into the Channel Country, it reaches a confluence with Eyre Creek that, in times of peak flow, empties into the Warburton River and ultimately into Lake Eyre.

The basin of the Georgina totals around 232,000 square kilometres (90,000 mi²), or about the same size as the Australian state of Victoria. Because it is so arid, however, its mean annual flow is only about 0.7 km³ (570,000 acre⋅ft). There is such extreme variation that — although streamgauging records are too poor to prove it conclusively — meteorological records leave no doubt that there have been many years of zero runoff in the entire basin (1905, 1928 and 1961 would without doubt fit into this category), whilst in very wet years such as 1974, 1977 and 2000, runoff can be as high as 6.28 km³ (5,090,000 acre⋅ft) or more.

Although a small part of the Macdonnell Ranges drains into the Georgina, most of the catchment is a flat as the Diamantina, though low ranges are very prominent in the north-west of the basin. This western part of the basin has sandy soils that are too infertile to provide nutritious fodder for cattle or sheep and a large proportion is an Aboriginal reserve. The eastern part of the Georgina catchment near Boulia is very similar to the Diamantina and Cooper basins, being grassy plains with heavy cracking clay soils that are quite fertile and provide very good feed in wet years for livestock. The Lake Machattie Area is an important breeding site for waterbirds.

Climatically, the Georgina catchment tends to be somewhat drier than the Diamantina or Cooper, with average annual rainfall ranging from around 400 millimetres (16 in) north of Camooweal to around 225 millimetres (8.9 in) at Bedourie.

Extremely dry years can give the entire basin less than 100 millimetres (3.9 in) whilst in 1974, 1977 and 2000 many areas had over 800 millimetres (31 in) and some as much as 1,000 millimetres (39 in). Almost all of this rain falls in the summer, and it is quite normal for the period from May to September to not record any measurable falls at all. In extremely wet summer months such as January 1974 or March 1950, most of the catchment can receive as much as 350 millimetres (14 in) in a month or 150 millimetres (5.9 in) in a day or two. Temperatures are generally hot, with most areas having maxima of over 30 °C (86 °F) on over 225 days per year. Frosts are rare but have been reported on occasions in all areas of the basin – however even in June and July maxima are around 25 °C (77 °F).

During severe floods the river can be as wide as 15 to 20 kilometres (9.3 to 12.4 mi) in the upper reaches and in the lower reaches from 25 to 30 kilometres (16 to 19 mi) wide. Inundation can last for months at a time, which can disrupt road and rail transport in the area. The highest recorded flood occurred in January 1974.