Rising north-west of in the Swords Range in Queensland, the river flows in a south-westerly direction through central Queensland and the Channel Country to form the Warburton River at its confluence with the Georgina River. In extremely wet years, the Warburton River flows as far as Lake Eyre. The length of the Diamantina River is approximately, and the basin is approximately, of which are used for agriculture. Most of the basin of the Diamantina is very flat—even the highest points in the northeast do not reach above sea level and Lake Eyre itself is below sea level. Apart from a few streams near Winton almost all rivers in the basin flow southwestwards towards Birdsville. The Diamantina River has no main channel, rather it is a series of wide relatively shallow channels. The major feature of the river's sluggish course is Diamantina National Park about halfway between Winton and Birdsville. Apart from the national park, almost all land in the basin is used for grazing cattle and sheep, though numbers fluctuate greatly and considerable skill is required on the part of graziers. The variable drought and flood cycles of the area make the river ephemeral with many semi-permanent waterholes. The highest recorded flow rate of the river was at Birdsville in 1974 with was measured. The Diamantina runs along the northern and eastern rim of a roughly circular zone measuring some 130 km across that has been identified by Geoscience Australia as a crustal anomaly. Proof is currently lacking as to the cause, but it is believed likely that the anomaly was caused by an asteroid strike that happened about 300 million years ago.
Environment
Climate
The climate of the basin is hot and arid. In January, temperatures throughout the basin average around during the day and decline only to about at night. In winter, they typically range from during the day to at night. On occasions, however, frost has been reported in all areas of the basin: Winton has recorded minima as low as.
Precipitation
Rainfall is heavily concentrated between December and March: averages for these four months range from at Winton and Kynuna to around at Birdsville. In the rest of the year rainfall is very scanty and only on the rarest occasions are significant falls reported: throughout most of the basin the average rainfall between May and September totals around. However, the rainfall of the basin, as with all of the Lake Eyre Basin, is exceedingly erratic and catastrophic droughts and floods tend to be the normal state of affairs throughout this region. In the northern part of the basin, annual rainfalls as high as were reported in 1894, 1950, 1974 and 2000, whilst even in Birdsville annual totals as high as have been reported. During floods the river can be as wide as across. In dry years such as 1902, 1905, 1928, 1961, 1965 and 2002, almost the whole basin reported totals. There can also be significant variation from station to station over small areas: although the annual averages and variability at Winton and Kynuna are almost alike, the actual totals at the two stations can differ by as much as in some years due to isolated very heavy rainfalls.
Soils
The soils in the region are mainly grey and brown vertisols, with some fluvents in the drier areas. Although they do not have high phosphate contents, they have adequate levels of most other nutrients: consequently when rainfall is abundant the grasses within the basin are extremely nutritious, especially in the lower reaches of the river around Birdsville, which is a primary region for cattle fattening in years when rainfall further north is adequate to flood the region.
The river is ephemeral but floods periodically following heavy rainfall events in the catchment. During the floods of 1940 the mailman, Harry Ding, completed his round using a motorboat and Cooper Creek was measured at around wide. In 1950 flooding covered some, with the river described as a raging torrent wide. Karuwali is a language of far western Queensland. The Karuwali language region includes the landscape within the local government boundaries of the Diamantina Shire Council, including the localities of Betoota and Haddon Corner.
