Fighting fire with fire

Researchers at Scion are playing with fire in a bid to help fight future forest blazes in New Zealand.

Together with rural firefighters, they are setting fire to harvested corn fields around Darfield in Canterbury as part of a month-long trial to learn more about how wild fires behave, in order to develop advanced plans to fight them.

It is predicted that New Zealand will see an increased number of ‘extreme fire’ events in the future as a result of climate change and these will be more unpredictable and create more danger to those fighting them.

Climate change is expected to bring longer periods of heat over summer months and also increased wind across the country. Under these conditions, small fires can easily get out of hand and become large conflagrations, threatening large tree plantations, as well as rural communities.

In order to better understand the behaviour of fires, Scion is working with experts from the University of Canterbury, San Jose State and the US Forest Service's Missoula Fire Sciences Laboratory, conducting experiments with real fires.

They have been using controlled fires in fields of stubble to monitor the behaviour of flames with state-of-the-art sensors, meteorological equipment and filming the action from above with drones.

They are testing a theory about the spread of fire through what is known as ‘convective heating’, in which a draft of air pushes flames down onto a source of fuel (trees or dry grass), causes a massive spread of fire. Turbulence in the air causes updrafts and downdrafts that push the flame up and down, and understanding how all the elements work together will help scientists to build more accurate fire spread models that can be used to predict how fires will behave.

Laboratory experiments have already shown how the ‘convective heating’ theory works, but the fields test currently taking place in Canterbury are designed to see how it works in real life.

In addition to setting controlled fires in stubble fields, the scientists and fire fighters are also planning trials in gorse and areas of wilding pines to see how it works in larger vegetation.

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