A project undertaken by CSIRO Forestry & Forest Products and supervised by J Gould
Project Vesta is a comprehensive research project to investigate the behaviour of high-intensity bushfires burning under summer conditions in dry eucalypt forests of differing fuel age and understorey vegetation.
The project brings together research scientists and technical expertise in bushfire behaviour from CSIRO Forestry and Forest Products and the Department of Conservation and Land Management (CALM), Western Australia. Fire management and research staff from land management agencies and fire authorities in New South Wales, Queensland, South Australia, Tasmania, Victoria, and Canada were also involved in fieldwork at various stages of the project during the 1998 and 1999 field experiments in Western Australia.
Project Vesta researchers conducting fuel sampling survey in 9-year-old experiment plot in jarrah forest, Western Australia
Erection of 30-m tower used to record wind speed above the canopy in the open.
Fire researchers prepare to hoist a wind vane with data logger and anemometer to the top of a 5 m tower as part of a wind study.
Ignition of experimental fire using drip torch. Fires were lit in experiment plots 200 m by 200 m using an ignition line length of 120 m. Fires were then allowed to burn across the plot and their rate of spread was measured.
Aerial view of Project Vesta fires. Between 4 and 5 fires were lit simultaneously in experiment plots of different fuel age but under the same fire weather conditions.
Project Vesta experimental fires. A team of three researchers observed each fire, recording aspects of fire behaviour, wind and fuel.
Over 100 fire behaviour experiments were conducted during the summers of 1998, 1999 and 2001 by CSIRO Forestry and Forest Products and CALM. These experimental fires were lit from 120 m long ignition lines in 4 hectare plots (each 200 m by 200 m) that had been intensively sampled for information about the fuels present. Fire behaviour ranged from slow spreading surface fires to fires of moderate intensity (7000 kW/m) with sporadic crowning. Wind speeds at 30 m height in the open ranged from 6.6 to 20.0 km/h.
Funding from the Hermon Slade Foundation enabled an additional project, in conjunction with the experimental fires, to study the structure of the wind beneath the forest canopy. A variety of configurations of multiple anemometers were used to do this and the most comprehensive set of measurements of wind associated with forest fire behaviour was collected. The aim of the study was to provide the best possible measure of wind strength, and its clearly defined error, to assist with the development of a new empirical model of fire spread.
The Vesta research team has undertaken a preliminary analysis of the fire behaviour data and believes that the extremely rapid development of the experimental fires has important implications for firefighter safety. The initial analysis focused on the rapid growth of a fire from a line of flames after a change of wind direction, and led to the development of safety guidelines for firefighters engaged in parallel attack of a fire front (which has been termed the dead-man zone).
Analysis of the wind study data reveals that the presence of the fire has a major influence on the wind speed measured behind the fire front, with increases up to 10% over measurements without the presence of the fire. It was also found that the variation of wind speed within the forest was much greater and more spatially variable than first thought. Wind gusts did not travel more than 40 m under the canopy and the 5-minute mean wind speed measured at one location could be up 40% higher or lower at another location.
New information on fire behaviour and firefighter safety emerging from Project Vesta will have application across Australia. During the next two years, CALM and CSIRO fire scientists will continue to analyse the data from these experiments and publish the results in a wide variety of media.
The outcomes of the project will include better information on fire behaviour and improved firefighter safety by providing:
- an improved fire behaviour prediction system that can be applied to dry eucalypt forests throughout Australia irrespective of species composition and fuel structure at local and regional levels;
- new information about the relationship) between fire spread and fuel characteristics (i.e. load, structure, age etc.);
- new information about the nature of wind beneath forest canopy and the relationships with fire behaviour;
- scientific information for improved fire management planning systems; and
- better estimates of potential fire threat at the urban/forest interface.