AT THE POINT
Location: This confluence point is in south-western Queensland, adjacent to the Qld-SA border. The area is on the eastern margin of the Simpson Desert, The degree confluence is located in the corridor between linear dunes that trend SSE-NNW. Access to the point is by 4WD track running west from Birdsville. Travel to the confluence is completed by going ‘cross-country’ along a wide inter-dune corridor. The nearest settlement is Birdsville (Qld), about 36 km in a straight line to the ENE. The site was visited by a party of RGSQ members travelling in four 4WD vehicles from Brisbane in May, 2008. The site lies within Diamantina Shire.
The Landscape: The point is located on a wide, flat swale between high lineal dunes whose summits are about 4km apart. The dune trend is SSE-NNW. These dunes are complex in construction, with lower subsidiary dunes nearby, also running in the same direction. The minor dunes frequently separate and rejoin. The dune sand is predominantly pale yellow in colour. Small gibber fields occupy parts of the flat area in sight of the point. At the confluence are low clumps of course grasses with bare soil patches between. Nearby are scattered low bushes.
The geology of the area around the point is aeolian sand of Cainozoic origin (less than 66 million years) though most is probably of Holocene age (less than 1 million years).
Point information and photos: Paul Feeney, Mary Comer with additional material by Col and Jo Grant.
WITHIN THE DEGREE SQUARE
The Country: The square is dominated by the dune fields of the Simpson Desert and the indeterminate perennial drainage patterns of watercourses such as Eyre Creek and the larger Diamantina River that make up the Channel Country. The parallel ridges of the dune field trend NNW-SSE and are composed of aeolian sands mostly of Quaternary age (less than 6 million years). There are small areas in the north-east of the square where Albian age (100 million years) sandstone form the surface while the drainage lines are composed of Quaternary alluvium. Patches of gibber are also found in the north of the square along with small (usually dry) lagoons.
Vegetation in the swales between the dunes includes low open shrublands and open Spinifex tussock grasses. Along the larger drainage channels are scattered patches of riparian woodland of River Red Gum and Coolibah with Lignum as the understory. Stands of Gidgee extend away from the drainage lines.
The vegetation varies greatly depending on the season and the time since the last period of good rains. The quality and quantity of vegetation also dictates the viability of the main rural activity of cattle grazing. During extended droughts the area can become largely de-stocked. Conversely during periods of good rain when the rivers flow and waterholes are full the explosion of wildlife, especially water birds is spectacular.
The Climate: The climate of the area is classified as being hot persistently dry desert. The Bureau of Meteorology climate station at Birdsville Police Station provides representative statistics.
Birdsville Police Station (038002) 1892-2011 (elevation 47 m ASL)
The highest temperature ever recorded in Birdsville was 49.5oC in December 1972 while the lowest temperature was -1.7oC in June 1965 and July 1965. Rainfalls also vary greatly. The highest total of 541.8mm was recorded in 1916 and the lowest total of 33.2mm in 1913.
Extremes of Nature: The national cyclone database maintained by the Bureau of Meteorology shows on cyclone that has tracked within 200km of the point, indeed TC Alan in February 1976 came within 50km of the point. This cyclone formed in the Coral Sea. Such storms can bring destructive winds and torrential rain which can produce flash flooding.
Cyclone tracks within 200 km of the confluence, 1906 to 2006 (Bureau of Meteorology web site)
Floods in the Diamantina River can spread across a very wide area though their depth and velocities are typically relatively low. They can lead to stock and fencing losses and properties can be isolated for many weeks due to flooded roads. There have been 10 significant floods in the Diamantina since 1950, the worst of them being in January-February 1974 when the peak was recorded at 9.45m on the Birdsville gauge. In 2010 and 2011 extensive flooding also occurred - the peaks reached 7.90m and 7.95m respectively at Birdsville.
Flood waters across the Diamantina flood plain and SES flood boat in 2010 (KG, 2010)
The area experiences, on average, between 15 and 20 thunder days each year. Severe thunderstorms can bring destructive winds, intense rainfall that can produce flash flooding and lightning. Storms in the dry winter period can spark bushfires if there is sufficient fuel to promote spread. The area can experience extreme heat throughout some of the year, with Birdsville having an average of 122 days annually with maximum temperatures equal to or over 35°C and 45 days over 40oC. The hottest months are December to February. Such extreme temperatures can cause heat stroke and death if appropriate measures are not taken such as avoiding strenuous physical effort, keeping as cool as possible and drinking lots of water. Heat waves kill more people in Australia than all other natural hazards combined. The National Earthquake Database maintained by Geoscience Australia contains no earthquakes within the degree square.
The Indigenous Story: The area around Birdsville is the traditional country of the Yarluyandi people and the area to the west is Wangkamana country.
MORE INFORMATION WELCOME
European Exploration and Settlement: The first Europeans to pass through the area were in the party led by Charles Sturt in 1844-5 however the harsh conditions kept the area largely unexplored until the 1860s. William Landsborough named the Diamantina River in 1866 and the original settlement known as Diamantina Crossing, grew around the store built by Matthew Flynn in the late 1870s to serve the drovers and teamsters travelling the north-south route to markets in Adelaide. The town was given its present name in 1885 though there is conjecture as to what inspired the name. Some say it was because of the many birds that occupy the local lagoon while others claim it was to be named after a local store keeper Mr J Burt (‘Burtsville’?). Until Federation in 1901 Birdsville served as a customs post to collect tolls on cattle and other stock entering South Australia. At the height of its development during the heydays of the Kidman cattle empire Birdsville boasted a population of 90 Europeans and 180 Aborigines. Some of the early buildings, such as the Royal Hotel, built in 1883, and the Birdsville Hotel built in 1884 are still in existence.
Today: The total population of the degree square at the 2011 national Census probably in the order of 270, most of them living in Birdsville. This population fluctuates considerably during the year, reaching its peak of probably more than 1000 during the annual Birdsville Races.
Cattle grazing is the mainstay of the local economy though tourism, especially for the Birdsville races in September each year provides a seasonal boost.
The square contains about 340km of public roads including the southern end of the Eyre developmental Road and the northern end of the Birdsville Track. There are many other kilometres of station tracks as well. There is a sealed all-weather airstrip at Birdsville and a geothermal power station. Birdsville provides a basic level of services including accommodation, food, fuel and mechanical repairs.
Birdsville, isolated settlement (Google Earth image)
Compilers: Ken Granger, 2011
References: various web sites including EPA, local governments, tourist industry and Bureau of Meteorology.
Queensland Museum, 2003: Discovery guide to outback Queensland, Queensland Museum, Brisbane.
Edited by: Hayley Freemantle