Everything about The Georgina River totally explained
The
Georgina River is the north-westernmost of the three major rivers of the
Channel Country in western
Queensland that flow in extremely wet years into
Lake Eyre.
The river rise from several smaller streams over a wide area of northwestern Queensland and the uppern
Northern Territory. These include the
Burke River, flowing through the basin's major town of
Boulia, the upper Georgina River itself rising in the
Barkly Tableland north of
Camooweal, the
Ranken River rising in the extreme east of the Northern Territory beyond
Tennant Creek, and the
Sandover River. The Sandover, unlike all other tributaries of Lake Eyre, flows northwards from the
Macdonnell Ranges to enter the Georgina in very wet years near
Urandangie.
The basin of the Georgina totals around 232,000 km², or about the same size as the Australia state of
Victoria, but because it's so arid, its mean annual flow is only about 0.7 km³ (or 570,000
acre feet). However, there's 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, and several others are likely to as well were decent data available), whilst in very wet years such as 1974, 1977 and 2000, runoff can be as high as 6.28 km³ (5,100,000 acre feet) or more.
Although a small part of the rugged 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
soils that are too infertile to provide nutritious fodder for
cattle or
sheep and a large proportion is
Aboriginal land. The eastern part of the Georgina catchment near Boulia is very similar to the Diamantina and Cooper basins, being flaw grassy plains with heavy
cracking clay soils that are quite fertile and provide very good feed in wet years for livestock.
Climatically, the Georgina catchment tends to be somewhat drier than the Diamantina or Cooper, with average annual rainfall ranging from around 400
mm (16
inches) north of Camooweal to around 225mm (9 inches) at
Bedourie. Extremely dry years can give the entire basin less than 100mm (4 inches) whilst in 1974, 1977 and 2000 many areas had over 800mm (32 inches) and some as much as 1,000mm (40 inches). Almost all of this rain falls in the summer, and it's 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 350mm (14 inches) in a month or 150mm (6 inches) 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).
Although it's the driest of the three main rivers of the Lake Eyre Basin, there's evidence that the Georgina has, in the past, actually reached the lake more frequently than either the Diamantina or Cooper. Some wave built shingle terraces suggest that during the
Medieval Warm Period Lake Eyre held permanent water. Large increases since the late 1960s in rainfall over the Northern Territory and pastoral areas of
South and
Western Australia that have
not been duplicated over Queensland do suggest an enhanced
greenhouse effect in the Medieval Warm Period may have caused the Georgina to
regularly fill Lake Eyre. However, far too little evidence exists for any certainty of this.
Further Information
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