AT THE POINT
Location: This confluence point is located in central Queensland, on the property ‘Boree Downs' after which the degree square is named. The closest settlement is Arrilalah, approximately 37 km to the north-west and Isisford is 50 km to the south-east. The point lies within Longreach Regional Council. Access to the point is via property tracks, and across country. The site was visited in the late evening by a party of RGSQ members travelling in 4WD vehicles from Brisbane in November 2009. While the confluence itself is unmarked, a GPS was used to find the exact location (accurate to within a few metres). An old survey marker was located near the confluence point.
Old survey mark near the confluence point (Paul Feeney, 2009)
The Landscape: Elevation at the degree confluence is 225 m, and the landscape is characterised by a flat plain, with surface material of sandy/clay loam with outcrops of sandstone rock. Aside from almost complete grass cover, there are some sparse trees (heights 4-5 m). A fox was sighted at the confluence, as were sheep and horses of the property in the nearby area. There are no human features visible at the site, but numerous bores in the surrounding area.
Butler Creek is the closest watercourse to the confluence, approximately 700 m to the west. It eventually joins with the Thomson River to the north-west, which is part of the Lake Eyre Basin. The primary geological feature of the area is Winton Formation sediments such as sandstone, mudstone and siltstone of Albian age, (100 million years).
Point information and photos: Paul Feeney with additional material by Jo Grant, 2009
IN THE DEGREE SQUARE
The Country: The landscape of the degree square is dominated by the floodplains and braided streams of the Thomson and Barcoo Rivers. The country is generally flat to low undulating with elevations generally around 200 m ASL. The geology across the square is dominated by the sandstone, mudstone and sitstone of the Winton Formation which is of Albian origin (about 10 million years). The floodplains of the two main rivers and their tributaries are alluvial sediments of Quaternary origin (less than 1.6 million years).
Much of the square is grassland though patches of low open forest is found on some of the higher points to the south of the confluence point. Riparian vegetation dominated by Coolibah and River Red Gum are found along the drainage channels of the main rivers.
MORE INFORMATION AND PHOTOS WELCOME
The Climate: The climate of the area is classified as hot grassland with a winter drought. The Bureau of Meteorology climate station at the Isisford Post Office provides representative statistics. The variability of the rainfall and temperatures may be seen in the table.
Isisford Post Office (036026) 1885-2010 (elevation 203 m ASL)
The highest temperature ever recorded in Longreach was 47.0° in January 1973 while the lowest temperature -2.0° in August 1974. Rainfall also varies greatly. The highest total of 1309.1 mm was recorded in 1950 and the lowest total of 125.3 mm in 1938.
Extremes of Nature: The cyclone database maintained by the Bureau of Meteorology shows 8 active or former cyclones have tracked within 200 km of the confluence point since 1906. Of these, one passed within 50 km of the point: TC Althea in December 1971. All of these storms brought heavy rain falls that produced flooding in both local and regional catchments.
Cyclone tracks that passed within 200 km of the confluence point 1906-2006 (BoM web site)
The area receives between 20 and 25 thunder days on average each year. The more severe thunderstorms can produce destructive winds, intense rainfall that may cause localised flash flooding, and lightning strikes may spark bushfires if there is sufficient fuel for it to spread.
Records of large floods in the Thomson River system extend back to the later 1800s. Major floods at Longreach (just north of this square) have occurred in 1893, 1906, 1949, 1955, 1963, 1974, 1990 and 2000. The highest flood in recent decades was that of February/March 2000 which reached a peak of 5.62 m on the Longreach gauge. A gauge height of 4.0 m is considered to be a major flood though a height of 5.4 m is needed for waters to enter the town.
Drought and heatwave remain the most frequent and severe natural hazards. Isisford averages 99 days a year (50 years of records) with temperatures of 35oC or more and 20 days a year with temperatures of 40oC or greater. Heatwaves kill more people in Australia than all other natural hazards combined.
The National Earthquake Database maintained by Geoscience Australia contains no event epicentres within the degree square.
The Indigenous Story: The land between the Thomson and Barcoo Rivers is the traditional country of the Kuungkari people.
European Exploration and Settlement: The first European to pass through this area was probably Augustus Gregory in 1858 in his search for Leichhardt. Sheep graziers followed and by 1875 the Whitman Brothers had established a store at Isisford. That settlement was established in 1877.
MORE INFORMATION WELCOME
The total population of the degree square at the 2011 national Census was less than approximately 200, most of whom were residents of Isisford. Like many settlements in the west, the population has been in decline for many years. This is in part the result of lengthy episodes of drought and the improvement in road transport to move stock and other goods.
Isisford, which sits on the west side of the Barcoo River, has a limited range of commercial services and few public services.
Isisford (Google Earth image)
The dominant land use across the square is sheep and cattle grazing. There are 2060 km of public roads within the square including a section of the Thomson Developmental Road. In addition to the public roads there is an extensive network of private roads on the numerous stations within the square. There is an airstrip at Isisford and many properties have their own airstrips for light aircraft.
There are no national parks within the square which falls mostly within Longreach Regional Council. There is a small section of Barcoo Shire in the south-west corner.
Compilers: Ken Granger, 2010
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.