Threshold and pattern dynamics may allow everything from earthquakes, drougths and even epidemics to be predicted
Credit: AFP
The damage is caused when soil is swept up off the land by floodwaters and deposited in rivers, lakes and dams. The removal of sediment from the land exposes infertile and unworkable soils, while their dumping in rivers or the sea can lead to outbreaks of algal blooms or the smothering of coral reefs.
To understand how this system works Prosser, has studied the history of floods and erosion in Australia over thousands of years. "We looked into gully erosion in the past 10,000 years and found that it is a natural process of the continent," he says. "But in the past 200 years it has increased in intensity and frequency."
With climate change expected to bring more floods it is the condition of the land that will determine their impact, says Prosser. "Good vegetation cover is the key to preventing erosion. A landscape with very good grass cover and vegetated valleys can withstand a one-in-100 year flood event and resist the effect of erosion."
But fires, drought and overgrazing cause the loss of protective vegetation. These degraded habitats take years to recover their natural resistance to erosion and during this time are at high risk of losing their soil. Special care and management is needed to prevent this.
Prosser's latest research aims to predict the impact of flood events so that their risks can be better managed. It aims to identify the point at which flooding reaches sufficient strength to move soil particles and so erode the landscape. Predicting when this threshold will be crossed is now greatly assisted by threshold and pattern dynamics.
"The ideal way for a drought to break is with gentle winter rains and steady vegetation growth," says Prosser. "But if major floods occur, they can have severe effects anywhere that land cover is poor. In these conditions there need to be changes in land management practices to offset the increased risks posed by floods under climate change."
John Finnigan of the CSIRO says human relationships are now recognised as a vital ingredient in complex systems such as disease epidemics, protected marine areas or salinity outbreaks. His research explores how the relationships between people form a single connected network – and how the patterns within networks control what the group might do and how they interact with their environment. This new approach sidesteps the very difficult problem of trying to predict the behaviour of large groups of people.
Landscapes with people in them are very complicated social, biological and economic systems, Finnigan says. "Individual actions add up and can impact the whole system. Even with the best intentions, the results of many individual decisions can be almost impossible to predict.
"We are now starting to understand that the pattern of connections between people through friendships, family ties or economic transactions can put strong bounds on what happens in a particular region."
This novel way of looking at systems is giving scientists new tools to predict, control and sometimes prevent disastrous events like disease epidemics or algal blooms which are usually the result of a system reaching a threshold.
The foot and mouth disease (FMD) outbreak in England - in which tens of thousands of animals were slaughtered - was due primarily to a drastic increase in contacts between livestock herds across the U.K., says Finnigan. More animals were being trucked longer distances to other farms or to fewer abattoirs. This meant that distant farms become so interlinked that when one animal contracted FMD the infection could spread rapidly through the whole herd. The livestock network had passed a ‘connectivity threshold' and the disease was able to become rampant.
Finnigan says that while network theory can't predict the likelihood of an initial disease outbreak, it can determine how quickly it can spread and how difficult it may be to stop it. It can also identify where and how the outbreak can be intercepted.
In future, network theory may help prevent a global epidemic - such as Asian bird flu - by predicting whether it is possible to stop the disease. "If it tells you that once a disease has started spreading you will never catch it, then you might be advised to start changing the network now, so as to keep the epidemic contained," says Finnigan.
Australian scientists, with their strengths in Earth sciences and complex systems science, are making a potent contribution to world advances in threshold and pattern dynamics theory, says Sivapalan. "These two areas are bringing the theoretical tools and analytical wisdom needed to attack problems in this field.
"These problems are so complex they cannot be solved by one or two fields of science alone, but they need a multi-disciplinary approach from many creative people with new ideas and insights. That is one of Australia's strengths," he says. "Threshold and pattern dynamics is an area of huge potential, and we are at the forefront. We must be sure we maintain our efforts."
Julian Cribb is a science journalist and Adjunct Professor of Science Communication at the University of Technology in Sydney.
Futuroception
It's always interesting to discuss whether everything is happening due to a terribly complicated game of cause and effect or whether the future is fundamentally unpredictable. I think this might be an unanswerable question. However, in the book 'Futuroception' Peter Lemans tries to give an answer and introduces futuroception as a common human sense. I would like to discuss his conclusions with other people, who have read the book.
Wayne
prediction
evrything is so interesting and sometimes you wonder if peopole are making it up and they just want ot make a little money. Now like everything else, science has taken over prediction. it kind of takes away the spooky-ness and the wonder. horoscopes are so old now.