Floods in central Australia

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Floods in central Australia

Post by Aussies-Online »

Penetrating even Sydney's invisible traffic jam of radio, television and mobile phone signals, the floods in central Australia have begun calling birds across the continent.

The torrents surging down the nation's desert waterways - the Diamantina, Paroo, Bulloo and Warrego rivers and Cooper Creek - have triggered an ecological shockwave that is now moving across the continent.

The severity of the drought meant that many birds, which normally inhabit wetlands in arid areas, took refuge on the coast, including in reserves in Sydney such as the Centennial Parklands and Sydney Olympic Park.

Already the flood front on the Diamantina is at Birdsville, water on the Cooper is flowing towards Innamincka and the rivers in northern and western NSW are virtually all in flood.

The water is a trigger for a boom period in the desert and is expected to lead to major waterbird breeding in central Australia.

Richard Kingsford, a wetland and waterbird expert with the Department of Environment and Conservation, said there had been some unusual visitors to Sydney in the past 12 months but many had begun to leave and more would do so.

Visiting Centennial Parklands this week Dr Kingsford observed that pelican numbers seemed to be down already, and he predicted that the unusually large numbers of black swans and cormorants observed along the NSW coast would also soon depart for the interior.

"A lot of birds in places like Centennial Park - things like hard-head duck, black swans, grey teal and some of the stilts - will soon leave," Dr Kingsford said.

A ranger at Sydney Olympic Park, Judy Harrington, said most of the hard-head ducks had now left the park's water bird refuge.

About 50 red-necked avocets that arrived a few months ago had left in the past fortnight.

"They certainly got the word from somewhere," Ms Harrington said.

Also on the recently departed list are a big mob of hoary headed grebes and nearly 200 coots.

"It's just amazing. Suddenly they're all gone again. How on earth do they know?" Ms Harrington said.

No one is certain how the birds know of the momentous changes in the desert. "One theory is that they can detect intensive low pressure systems," Dr Kingsford said. Another is that the waterbirds recognise the changed weather conditions and begin to hop from one water body to another until they reach their big breeding grounds.

"They have a memory of where the landscape is," he said. "They can navigate by the stars and the Earth's magnetic field."
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Post by Aussies-Online »

Floods are filling parched river systems, bringing an explosion of new life to the outback, writes James Woodford.

Last week grazier Angus Emmott rejoiced as water covered more than half of his 52,000-hectare property on the Thomson River, south-west of Longreach in central Queensland.

But joy at Noonbah is about much more than the promise of a carpet of grass which will guarantee good economic times into the middle of this year. For a family with a cicada, two reptiles and a splendid wren named after them there is no better time to hunt for species unknown to science.

An ecosystem knocked unconscious by severe drought has been revived by a drenching, and across the outback life has exploded.

While many of the Emmotts' neighbours are cursing the eruption of sandflies, which make going outside almost intolerable, the Emmott family are hunting for new and bizarre critters with butterfly nets.

At Noonbah it is as if the 24 species of cicada and countless other invertebrates, 15 types of amphibian, freshwater crabs, blue clawed yabbies and fish have suddenly woken up. The property's 500 different trees, shrubs and forbs are flush with new growth and waterbirds have magically appeared in the wake of the flood.

"You have this desolate landscape and then the flood front comes through and you have a whole chorus of frogs. Dragonflies are everywhere and everything just booms," Emmott says. "Within two days of the rain finishing, the cicadas were out. All the fish are heading upstream. There are caterpillars everywhere. Insects everywhere."

INLAND Australia is a boom or bust environment and nothing kick-starts the party like a big pulse of freshwater down the nation's biggest arteries.

The Diamantina and Cooper, which both drain into Lake Eyre, are in flood. The Paroo, Gwydir, Macintyre, Namoi and Warrego - all tributaries of the Darling - are also running and, depending on how much is pumped out by irrigators, it is likely that water will reach at least as far as the Menindee Lakes system.

A waterbird and river expert with the NSW Department of Environment and Conservation, Dr Richard Kingsford, says that because the Darling system is so dry - wetlands parched, government and private dams empty - it is unlikely any water will make it all the way to the Murray.

Compared with the amount of water that can potentially end up in Central Australia, these floods are minor - special only because of the severity of the drought they are extinguishing.

However, the current "flush" will fill the rivers and if in the next few months another big low pressure system empties itself in Queensland, then Central Australia could be transformed for years to come.

"It now has the potential to be a monster flood if we get more rain," Kingsford says. "If in the next month we get another big depression, it will take off. The whole system is primed and the next flood will go straight over the top and get further, faster."

Already the Diamantina flood front has reached Birdsville and will probably make it to Lake Eyre. The Cooper Creek "fresh" has passed Windorah and is on its way to Innamincka. But because the enormous Coongie Lakes system is dry, Kingsford doubts any Cooper Creek water will reach the giant salt pan this time unless there is more rain in the catchment. "The question on everyone's lips is 'how far will the water get?"' Kingsford says. "No one knows how far it's going to reach."

The floodwater in both of these systems moves forward like a rising tide. "You can walk in front of the flood when it gets to the flood plains," Kingsford says. It is just ahead of this moving water that birds get to have their first big feast. "In dry times the grasshoppers, spiders and other invertebrates have all made homes in cracks and the waterbirds follow the flood front and as the insects emerge from the cracks - that's the first bonanza for the waterbirds."

If there is more rain and the Cooper Creek/Diamantina River/Lake Eyre system goes the full monty, then the resulting inland sea will be one of the richest waterbird havens on earth, with as many as a million feathered pilgrims mysteriously arriving for a frenzy of breeding.

Last year, a Charles Sturt University researcher, Dr David Roshier, attached eight satellite tracking devices to grey teal which were taking refuge with thousands of other waterbirds at Lake Hope between the Birdsville and Strzelecki tracks in the far north of South Australia. All were named after characters in James Bond movies.

For months the birds stayed close to one of the last big water bodies in Central Australia but in the last few weeks a cue, which scientists do not understand, has prompted several to make extraordinary journeys of more than 300 kilometres.

One of the ducks, nicknamed "Q", flew from Innamincka to the floods near Windorah in one big push on January 18. "It's a long way to go to something that you don't know is there," Roshier says, "so they must know it's there."

An associate professor at the University of Canberra's Co-operative Research Centre for Freshwater Ecology, Martin Thoms, says the current flows heading towards the Darling River will inundate about 75 per cent of the 600 wetlands between Mungindi and Menindee. These floods, he says, have the potential to be of much longer duration than the last major flood, in 1996.

As the chain of wetlands in northwestern NSW fills they will connect, and species which have been isolated in disappearing billabong pools will be able to break out and travel through the system.

"This flood will be important for native fish," Thoms says. "All the food webs will be stimulated. It will be party time for a lot of our native flora and fauna."

Already Nocoleche Nature Reserve, just south of Wanaaring, is awash, and those working in the western region of the NSW Parks Service anticipate that the newly acquired Peery Lake within the Paroo-Darling National Park will follow.

"When Peery Lake fills it could be spectacular," says Kingsford. "It can be 30 kilometres long, five kilometres wide and 40,000 to 50,000 waterbirds breed there - things like pelicans and brolgas."

The drought has been crucial for the current boom because all of the dead dry vegetation will now rot under water, providing millions of tonnes of food. The landscape has been like a giant freeze-dried meal. "Just add water to it and it takes off," Kingsford says.

Near the bottom of the food chain are almost invisible micro-invertebrates, creatures like water fleas that have survived as dormant eggs, waiting in the dried sediments for the arrival of a flood. Many tens of thousands of these eggs per square metre can lie for decades until water triggers birth in mind-boggling numbers. Their emergence is similar to the hatching of the popular pets called sea monkeys. Within hours of adding water they begin to spring back to life.

The University of New England scientist Dr Kim Jenkins has studied these micro-invertebrates in lakes near Menindee, and at times the densities of freshly hatched water fleas are as high as 1000 animals per litre. "We have hatched them from lakes that had been dry for 50 years," Jenkins says.

Such discoveries raise as many questions as they answer but clearly show how intricately and delicately balanced life has become in the outback, especially in places where the waterways are essentially running naturally, such as rivers in flood like the Cooper, Diamantina, Paroo, Bulloo and Warrego.

"These rivers are unregulated," Kingsford says. "They're still wild rivers, they're still going through the same boom and bust periods they have gone through for thousands of years. The plants and animals have adapted to that. It really is quintessential Australia. The rivers define the inland. They determine the ecology of those systems and the continent and we have got to get used to living with the landscape and understanding that these cycles come and go, instead of thinking that we can tame the rivers."
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