24°S 138°E Ethabuka – Queensland by Degrees

AT THE POINT

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Degree confluence 24°S 138°E, Google Earth

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Looking north

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Looking east

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Location: Degree Confluence 24°S 138°E is adjacent to, and east of, the Qld-NT border. At this location the border appears unmarked, with no evidence of a border track or fence. The site is deep within the Simpson Desert, and near the north-western corner of the Simpson Desert National Park. The confluence is in an inter-dunal corridor between SSE-NNW trending linear dunes that are about 200m apart.

There is no direct access to the location. The RGSQ expedition visited the site, travelling the final part of the trip across the dune field on two quad bikes from base camp on Ethbuka station. The nearest settlement is Bedourie, Qld, about 150 km in a straight line to the ESE. The RGSQ members travelled in four 4WD vehicles from Brisbane in May, 2008.

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The access track to the confluence point

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Preparing the quad bikes for use

Landscape: Degree Confluence 24°S 138°E is on an undulating surface located in an inter-dune corridor, within the Simpson Desert. These dunes have soft, sandy summits and slopes. Natmap (250K Raster Maps) indicates average height of dunes around the confluence is 10m.

The Quaternary aeolian red sand of the Simpson Dunefield has been shaped by the wind into SSE-NNW aligned linear dunes. While the dunes are largely stable and moderately vegetated, exposed parts are subject to wind action.

Spinifex, low bushes and some small trees are present at the confluence point.

While the area is considered to be part of the Lake Eyre Basin, there is no visible drainage pattern at the confluence. The closest watercourse to the point is the usually dry Gnallan-a-gea Creek approximately 15 km to the east. Its direction of flow is SSE, parallel to the dunes.

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Google Image: Degree Confluence 24°S 138°E
Linear dunes at confluence
(3.2km across field of view) (no date given for image)

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Google Image: Degree Confluence 24°S 138°E
Linear dunes in area of confluence - lighter colour in west is burnt area
(9.8km across field of view) (no date given for image)

Point Photo Credits: Paul Feeney, Mary Comer

Point Information Prepared By: Jo & Col Grant

IN THE SQUARE

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Climate: The closest weather station is at the Bedourie Police Station (038000), which is 155km east-south-east of the confluence and has an elevation of 91m.

 

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Year

Mean max
(ºC)

38.8

38.1

36.2

32.5

26.8

22.6

23.3

2535

30.8

34.1

36.3

38.4

32.0

Mean min
(ºC)

25.1

24.5

21.7

17.4

11.7

8.2

7.6

9.1

14.4

17.9

20.9

23.5

16.8

Mean rain
(mm)

33.4

35.3

17.6

10.0

11.6

10.0

10.3

7.2

6.3

14.1

16.2

16.2

187.7

              

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

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Cyclone tracks within 200 km of the confluence, 1906 to 2006 (Bureau of Meteorology web site)

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 (1907, 1955, 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

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.

Today: The population of the degree square at the 2011 national Census was probably less than 5.

REFERENCES

Geoscience Australia, NATMAP Raster
Geoscience Australia, Scanned 250 K Geology Maps

Edited by: Hayley Freemantle