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Is Melbourne’s urban sprawl creating more bushfire risk?

After a year of what has felt like endless emergencies, bushfire season is here once again. It’s the time of year when residents of Melbourne’s fire-prone regions hold their breath a little. In areas like the Dandenongs, Grampians and Mallee, fire danger ratings are checked religiously. On some days, cars are packed ready, just in case.

Having a plan for bushfire season is part of life for homeowners in these regions. It’s a known risk of living there; in some places like Upper Yarra, bushfire history can span centuries. But what about the newer suburbs springing up as part of Melbourne’s urban sprawl? As Melbourne spreads and housing estates meet bush and grasslands on the city fringe, there’s more to consider than the threat of population growth on Melbourne’s food supply. More worryingly, are new fire hotspots being made?

Deakin’s Centre for Integrative Ecology studies the ecological effects of fires in Victoria. The centre’s director, Professor Don Driscoll, says urban planning is key to managing bushfire risk in Melbourne’s urban sprawl. ‘Careful urban planning is needed to avoid making the bushfire risk worse. That includes not increasing the interspersion of houses with forest or grassy areas,’ Prof. Driscoll says.

He suggests it’s a balancing act between fire safety and public access to green space. ‘People need a dose of nature, so there is a trade-off to be made between access to nature and living in high-density housing in a concrete jungle that will never burn.’

Human factor in bushfire risk

Having a high concentration of people living close to bush and grassland can heighten the fire risk. According to the Australian Institute of Criminology, more bushfires are started by people than natural causes such as lightning. Prof. Driscoll says although weather plays a large part, the key to managing risk is the human factor and prevention.

‘A combination of something to burn, weather and ignition influence fire risk.  The more severe the weather, the less important the amount of fuel is for carrying a dangerous fire. “Bushfires” often only incidentally burn forest. They can often spread over crops and paddocks, and under severe weather, you can be hard pressed to protect houses in their way,’ Prof. Driscoll explains.

‘But before any of that can happen, the fire has to start. Many ignitions are caused by people, either accidentally or deliberately. So the regulations and enforcement around access to public lands and use of machinery, or other sources of ignition on hot windy days, has a big influence on whether a fire will happen or not.’

'People need a dose of nature, so there is a trade-off to be made between access to nature and living in high-density housing in a concrete jungle that will never burn.'

Professor Don Driscoll,
Deakin University

Fire response in urban sprawl

A 2018 report on demographics and fire risk by the Department of Environment, Land, Water and Planning (DELWP) identified urban growth corridors to the east, north and west of Melbourne as areas with a high proportion of population vulnerable to fire. ‘Many of the areas with large increases in children are in the western and northern fringe areas which have exposure to grassfires’, the report notes. It also singles out growth in suburbs at the foot of the bushfire-prone Dandenongs.

An increased risk in bushfires also raises the issue of ensuring emergency services know how to adequately respond, something that has been explored with Deakin’s firefighting simulator, FLAIM.

But the risk of bushfire and grassfire in Melbourne’s outskirts hinges on good planning, according to Prof. Driscoll. ‘The biggest worry is urban planning: if an area needs to evacuate quickly, can the roads handle it, and can the emergency services swing into action to make that evacuation happen quickly?’ Prof. Driscoll asks.

‘Much greater focus needs to be given to preventing fires, making houses more fire-resistant and rapid response when fires start.’

The role of planned burns

Prof. Driscoll warns that planned burns on nearby bush and grassland can’t be relied on alone to keep residents safe. Understanding the importance of Australia’s biodiversity is critical, and Prof. Driscoll questions the role planned burns have in reducing bushfire risk. ‘There is compelling evidence that broad-scale fuel reduction burns in forests make no appreciable difference to the risk that houses will burn down,’ Prof. Driscoll says.

‘Lessons learned from the Black Saturday fires show that managing fuel close to a house, particularly within 40 metres, is what actually influences the risk that it will burn down.’

Prof. Driscoll suggests there are trade-offs to make when managing fire risk. ‘In most forest systems in southern Australia, you need to burn up to 10 times as much area as you can expect to prevent from being burnt in a bushfire. That is, to stop one hectare of forest being burnt in a bushfire, you need to burn up to 10 hectares in fuel reduction burns. That’s a lot of burning, a lot of smoke going into the air and into the lungs of people across vast parts of the country.’

Ultimately, the best way to face bushfire season in all regions is fire preparedness by government agencies and residents, according to Prof. Driscoll. ‘Fire safety is much more about urban planning, managing vegetation right next to houses, leaving early, prevention and rapid suppression, house construction standards and insurance.’

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Professor Don Driscoll
Professor Don Driscoll

Director, Centre for Integrative Ecology, Deakin University

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