AT THE POINT
Location: The site is in south-western Queensland, in the heart of Channel Country, and on the eastern edge of the Simpson Desert. The degree square is named after the Bilpa Morea Claypan, on which the confluence point is located. There is no direct access to the point. The Flood Bypass Road comes only within 20 km of the confluence, and the remaining distance was travelled by 4WD across country, a journey which can only be undertaken in the dry months.
The nearest settlement is Bedourie, which is approximately 88 km to the north-west. The site was visited by a party of RGSQ members travelling in four 4WD vehicles from Brisbane in May, 2008.
Marking the degree confluence
Landscape: The view from the confluence shows the flat terrain of the Bilpa Morea Claypan, which has an elevation of approximately 60m. Only a few tussocks of grass are found on the ground surface, and no other vegetation is visible in the vicinity. Geological features of the area include Quaternary alluvium such as clay, silt, sand and gravel (Scanned 250K Geology Maps, Geoscience Australia).
To the north of the confluence there is a small but dense field of outlying dunes from the Simpson Desert, which have an average height given as 20m (Natmap 250K Raster Maps). Here the dunes trend in a slightly different direction, that is SE-NW, instead of SSE-NNW.
The Bilpa Morea Claypan is a site of internal drainage for several local creeks, including Umpadiboo Creek to the east, and Gilmour Creek to the south-west. Most of the watercourses are typically dry, but can become swampy after heavy rains. There are also several waterholes in the surrounding country. The claypan lies between the Diamantina River and Eyre Creek, which are located 40km to the east, and 36km to the west-north-west respectively. While local creeks drain into the claypan, the degree square is regarded as part of the Lake Eyre Basin.
Point Photo Credits: Paul Feeney
Point Information Prepared By: Jo Grant
IN THE SQUARE
The Country: The dominant features within the square are the channels of the Diamantina River and the many perennial lakes that dot the landscape, the largest being the Bilpa Morea Claypan and Lake Machatti. There are also numerous sand dunes that mark the eastern extent of the Simpson Desert. Elevations range from around 100m ASL in the north and slope down to 50m in the south.
The geology of the area is predominantly sand dunes of Cainozoic age (less than 66 million years) and alluvial sediments of Quaternary age in the channel country. The vegetation is mostly sparse open tussock grasses and areas of tall open shrubland. During periods of good rain such as that experienced during 2010 and 2011 much of the area becomes waterlogged and flood waters can extend over many kilometres. During such times the area becomes a major breeding site for water birds, especially pelicans and cormorants.
The land use across the square is cattle grazing though during extended droughts the area is largely de-stocked.
The closest weather station is at the Bedourie Police Station (038000), which is 90 km north-west of the confluence and has an elevation of 91m.
The highest temperature recorded was 47.0°C in January 2004, and the lowest was 1.6°C in July 2004. The greatest rainfall recorded in a year was 485.1 mm in 2000, and the least was 33.4 mm in 2002.
These and other climate statistics for Bedourie can be found at: Australian Bureau of Meteorology, http://www.bom.gov.au/climate/averages/tables/cw_038000_All.shtml
Extremes of Nature: The area experiences extreme heat for much of the year, with Bedourie having an average of 139 days annually that have maximum temperatures equal to or over 35°C. The hottest months are December to February, all of which experience on average over 20 days with temperatures equal to or over 35°C. Bedourie is also located in one of the driest regions of Australia, and experiences only 21 days annually on average with rain.
Since 1906 there have been no cyclones to pass within 50 km of the degree confluence, but 3 within 200 km (1918, 1964, 1976). Cyclone information for this area and all of Australia can be found at the Australian Bureau of Meteorology website, http://www.bom.gov.au/cgi-bin/silo/cyclones.cgi
Cyclone tracks within 200 km of the confluence, 1906 to 2006 (Bureau of Meteorology web site)
Extreme heat and drought are also serious issues. Records show that Bedourie experiences 139 days annually with temperatures over 35°C, 49 of which typically reach 40°C or warmer. 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. In addition, with very little rainfall and only 21 days a year on average with any rain, the area is also among the driest in Australia.
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.
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 Bedourie having an average of 132 days annually with maximum temperatures equal to or over 35°C and 46 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 two earthquakes within the degree square. They were a ML 3.8 event on 11 July 1986 with an epicentre 18km north of Lake Machattie and a ML3.0 event on 11 July 2001 with an epicentre between Lake Machattie and Bilpa Morea Claypan. No damage was reported from either event.
The Indigenous Story: The land around Bilpa Morea Claypan is the traditional country of the Karuwali people and the land around Lake Machattie is Mithaka country.
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.
MORE INFORMATION WELCOME
Today: The total population of the degree square at the 2011 national Census was notionally 283, however, the 94,666 sq km of the Statistical Area 1 (SA1) that contains that population, covers 10 degree squares. The actual population is probably less than 50.
There are 516km of public roads in the square and perhaps an equal distance of private roads and tracks on the various cattle stations in the square.
Compilers: Ken Granger, 2011
Edited by: Hayley Freemantle
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.