Rain puts dampener on experimental burns

21 February 2008

A major research experiment on wild fire in Canterbury scrubland has been hampered by this summer’s temperamental weather, ranging from drought to floods.

Fire researchers from Crown Research Institute Scion, supported by numerous rural fire agencies, have conducted a large research project that involved setting fire to privately owned Canterbury scrub to improve understanding of fire behaviour on steep slopes.

The experimental burn programme was conducted on the Mt Torlesse Station near Springfield as part of an international research project into the behaviour of fires.

Ten days worth of burns were planned starting in late January, but only three days have been suitable due to rain in the Canterbury hill country.

Scion fire researcher, Grant Pearce, says the likelihood of getting sufficient drying in the coming weeks is very low, so the decision has now been made to stop the burning programme and retrieve all firefighting equipment from the site.

“Unfortunately, while drought has been experienced across the country this summer, the Canterbury hill country experiences a climate of its own and this summer, that has not been conducive to our research.

“In order for us to meet both the scientific objectives and strict health and safety controls, this research can only  be undertaken in very specific conditions so despite a spate of scrub fires in the region over previous weeks, we have barely been able to light a match.”

Despite these setbacks, they have managed to collect some valuable data from the completed burns.

“This research is aimed at helping fire agencies to better manage the serious risks posed by wildfire, particularly in terrain where extreme fire conditions can create unique hazards for fire fighters.

“Dry scrub fuels can burn with intense heat and long flames that move very fast uphill. This can create fire behaviour effects on steep slopes that are dangerous and often difficult to predict.

“In total, four of the six research burn blocks have been burnt, most of which exhibited extreme fire behaviour, and provided good information on fire spread rates and intensities,” Mr Pearce explains.

“One of the blocks burnt unsuccessfully in unfavourable conditions. However, even this provided useful information on the conditions required for successful ignition and fire spread, and on the relative power of the wind versus the slope to spread the fire under mild conditions.”

These experiments were generously supported by firefighting teams from the Department of Conservation, Selwyn District Council, National Rural Fire Authority and other rural fire authorities from throughout the South Island who sent fire crews to help contain the burns.

The research is being carried out in collaboration with Australian bushfire scientists from the Commonwealth Scientific and Industrial Research Organisation (CSIRO), with the support of the Bushfire Cooperative Research Centre in Australia.

“A huge vote of thanks is extended to all those organisations and individuals that have assisted with the project to date, including local fire authorities and their staff, and out-of region suppression resources,” says Mr Pearce.

The research is needed to enable land managers and fire agencies to better protect life and property.

Every year in New Zealand around 4500 wildfires burn some 7000 hectares of rural lands and fire risk is expected to increase with predicted climate change.

The current economic impact of forest fires alone is around $20 million per year, not including the equally devastating losses associated with damage to rural property and infrastructure.