Predicting the moods of a raging monster
Bushfires are notoriously unpredictable - but Australian scientists are starting to come up with reliable tools for predicting fire behaviour which may save lives and help to limit damage.
Fire researchers in the Bushfire Cooperative Research Centre are working on data from extensive experimental burns in Western Australia, New South Wales, and most recently, in New Zealand.
"Our aim is a simple and practical manual which can be used by fire managers and fire fighters on the ground, as well as researchers in the laboratory," says Mr Jim Gould of CSIRO's Bushfire Behaviour and Management Group, a partner in the Bushfire CRC.
Mr Gould says that the recent joint Australian-New Zealand experiments investigated fire behaviour on steep slopes in different wind conditions.
"Many of the dangerous and sometimes tragic 'burnovers' which have occurred in recent years have involved steep slopes when there has been a sudden change in weather behaviour," says Mr Gould.
"Heath and shrub vegetation types make up a very large proportion of the remaining natural vegetation in the most heavily populated parts of Australia and New Zealand," he says. "They make up a major component of the urban interfaces surrounding Sydney, Perth, and many bushland urban and rural developments in both countries.
"Our experimental fires have been designed to yield the maximum amount of useful data, especially with regard to the effects of slopes and gullies in scrub and heathland," says Mr Gould.
"An important part of recent experimental projects such as the 110 experimental burns conducted as part of Project Vesta in Western Australia, and Operation Tumbarumba in NSW, has been to validate existing guides and sets of tables.
"Project Vesta in particular demonstrated that the McArthur Forest Fire meter, familiar to generations of fire fighters, may seriously understate the predicted rate of spread of forest fires under dry summer conditions," says Mr Gould. Project Vesta has confirmed that the potential intensity and rate of spread of fires in dry eucalypt forest is directly related to the time since last fire. The intensity and difficulty of suppression of fires will increase for at least 15 years after fire because of changes taking place in fuel characteristics of the litter, shrub and bark fuels.
"Any prediction of natural systems depends on good data," says Mr Gould. "Weather prediction has significantly improved in the last decade through the increasing availability of better models and better data input. Bushfire prediction is following the same path, by getting an enhanced understanding of the variables which affect bushfire behaviour."
Mr Gould says that in the three major experimental projects, researchers used a
"... physical rather than a biological approach".
"We look at the forest or shrubs from a structural point of view. We describe the environment in terms of the physical components: the height, the amount of fuels, the amount of dead material, rather than species composition," he says. "Using those parameters, the resulting model is quite transportable from one part of Australia to another.
"As well as that, we add the moisture content or deficit, wind behaviour, and land-forms," he says.
Mr Gould says that the end-product of the current research will take several forms, ranging from a technical report, to computer programs, to a set of tables small enough to fit in a fire-fighter's pocket.
"This sort of work is never finished," says Mr Gould, "but the data gathered over the past few years is enough for us to formulate a report and design practical tools that will help fire managers and fire fighters in the bush.
"The first products will be available to the bushfire agencies by next season, to be tried out in the field," he says. "Our primary aim is to increase the safety of our fire fighters and our community."
The research addresses National Research Priorities one and four - a sustainable Australia and safeguarding Australia.
More information from:
Mr Jim Gould, Bushfire CRC, 02 6281 8341 or 0427 266 436
Derek McCormack, Bushfire CRC , 03 9412 9602 or 0419 550 609
Nick Goldie, CRCA Media 0417 299 586