WA BAL Report would like to explain fire behaviour in the hopes of better educating its clients to survive bushfire attack.
There are thousands of bushfires in Western Australia every year, making our state one of the most bushfire prone areas in the world. Bushfires can start and take hold with no warning, and can quickly become out of control if not extinguished immediately. WA BAL Report considers it important for you to understand how fires behave in order to better protect your family and your home and provides this information so that you are better prepared.
Bushfires need three things – fuel, air and heat, to spread and thrive. If you take away one of these elements, you will put out the fire.
Bushfires generate immense heat. Much of the heat dissipates into the air, but a significant amount of heat radiates at ground level, radiant heat spreads the fire by drying out vegetation so that it can burn. Radiant heat is a leading cause of death from bushfires as it can crack or break windows and allow embers in.
Burning embers are carried by strong wind and can infiltrate your home through gaps in the roof, walls, evaporative air conditions, windows and doors. They can land on materials that can easily burn and this can start a fire. Ember attack is the main reason that houses catch fire during a bushfire, and can threaten your home even after the fire front has passed.
Direct flame contact can also cause your house to be set alight. Removing heat is the most common way of fighting fires. Water can be used to soak up the fire’s heat.
Bushfires need air to continue and the more there is, the faster they burn. Small fires can be put out by removing oxygen and thereby smothering or starving the fire, however this is not practical in the case of bushfires as they are usually too big. Strong winds force the fire along and increase air circulation. Any change in wind direction or speed can rapidly increase the rate of spread and direction of the fire. Strong winds increase the fire’s temperature and pushes flames closer to fuel making the fire travel faster.
Fuel can be removed by, before a fire starting, conducting controlled burning or forest clearing. Before the bushfire season starts, you should prepare your home by clearing it of loose leaves, twigs, bush and other fuel sources that could pose a threat during a bushfire. During a bushfire, bulldozers are used to clear fuel and create containment lines.