Australian School of Petroleum The University of Adelaide Australia
LEBARG
Lake Eyre Basin Analogues Research Group

Flooding in the Channel Country 2009

- Latest satellite images

- Tracking the flood front through the Channel Country to Lake Eyre

- Background information on flooding in the Channel Country

 

Latest Satellite Images

24th April

 

Satellite images showing water flowing into Lake Eyre North along the Warburton and Kalaweerina Grooves.
14th March
21st March
28th March
1st April

Images are false-colour (bands 3-6-7). Dark blue colour is water.
NOTE: scales differ between images (images are not georectified)

Images courtesy of MODIS Rapid Response Project at NASA/GSFC


Images from 3rd April show the areas still flooded and vegetation growth in areas where floodwaters have subsided.
Bands 7-2-1. Green = vegetation growth
Bands 3-6-7. Dark blue/black = flood water

 

** CLICK HERE for more satellite images of this flood event, with images from before the rain, of the flow front through the Channel Country rivers and as the flow front spreads out into Lake Eyre **

 

Tracking the flood front through the Channel Country to Lake Eyre

Figure showing the location of the flood front as it progressed down the Georgina and Diamantina River systems to Goyder's Lagoon, along Warburton Creek and into Lake Eyre
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Trevor Wright of WrightsAir has a collection of great photographs of this flow event on his website here.

 

Background information on flooding in the Channel Country rivers and Lake Eyre

The Channel Country rivers of central Australia include the large river and floodplain systems of the Georgina and Diamantina Rivers and Cooper's Creek. These rivers flow for hundreds of kilometres, from headwaters in the tropics to Lake Eyre in the centre of Australia .

The Channel Country rivers are different from most other rivers in the world. They are called ‘Channel Country' because they have many channels across their floodplains (these types of rivers are called anabranching rivers), and their floodplains are usually between 10 and 70 km wide. They flow through semi-arid to hyper-arid climate zones and are ephemeral rivers, which means that they are dry for most of the year and have water flowing through them only after there has been enough rainfall in their catchments. This rainfall usually occurs during summer, related to monsoonal weather systems and sometimes cyclones in tropical northern Queensland .

The Channel Country landscape is very flat, and so when a flow event does occur, water often overtops the banks of the river and floods out over the wide floodplains. After rainfall in the upper catchments of these rivers, water flows downstream and the passage of the flood can be seen in satellite images. If there is enough rainfall, flood waters flow as far as Lake Eyre , and about once every eight years there is enough water to almost cover what is normally a dry, salty, lake bed. Because of the dry climate, much of the flood water evaporates and so sometimes flood waters will only reach part-way downstream. Lake Eyre is the fourth largest playa, or dry salt lake, in the world; it is 80 km wide and 150 km long. On average, about 80% of its surface is covered with shallow water once in eight years (Kotwicki and Allen, 1998).

The Diamantina-Warburton River system is responsible for bringing the most water to Lake Eyre . On average, water from the Diamantina River system gets as far as Lake Eyre once every two years (Kotwicki, 1986). Lake-filling events are much less common. The highest recorded lake filling event was in 1974, classed as a 1 in 100 year event, when water was -9.5 m AHD; or 5.7m deep in the deepest southern end of Lake Eyre North which has an elevation of -15.2 m AHD, or 15.2 metres below sea level.

The Channel Country rivers are interesting for scientists to study because we understand so little about how they behave compared with many other types of river (such as constantly flowing rivers with only one channel and a narrow floodplain). We are interested to find out things like what happens when they flood, how their shape and pattern in the landscape is controlled, and what the record of sediments they leave behind looks like.

 

References:
Kotwicki and Allen, 1998. La Nina de Australia - contemporary and palaeo-hydrology of Lake Eyre. Palaeogeography Palaeoclimatology Palaeoecology, 144, 265-280.
Kotwicki, 1986. Floods of Lake Eyre. Engineering Water Supply Department, Adelaide, 99 pp.

 

Compiled by Kathryn Amos ().