Ash Wednesday Bushfires
The many natural hazards that have occurred over the years have varied from cyclones to droughts, however bushfires are the main hazard Australia is prone to. A bushfire is an out-of-control fire that burns bush, forest and woodland areas. Australia has had a considerable number of hazardous bushfires, the Ash Wednesday Bushfires of 1983 is one of Australia’s most devastating.
Over one hundred fires broke out between February 16th-18th 1983, eight of which were major fires. These fires swept across regions of VictoJ.Dimovskiria and South Australia causing widespread damage. Figure 1 below is a map of Victoria, the red representing where the fires were formed. The eight major fires were started in the following areas of Victoria:
* Cudgee, Ballangeich and Framilingham
* East Trentham and Mt Macedon
* Belgrave heights and Upper Beaconsfield
* Warburton and
An ignition flame point is needed for a bushfire to start. This ignition is caused naturally by lightning strikes or by a deliberate/accidental flame for example arson, camping fires or carless behavior. Most of the Ash Wednesday fires were caused by an accidental ignition, for example in Cudgee, Mt Macedon, Monivale and Branxholme. The suspected cause for these fires was the clashing of electrical powerlines with tree branches.
Bushfires can be influenced by several factors. It is primarily the weather conditions and geographical processes that dictate the behaviour and spread of a fire.
Drought plays an essential part in the environment desiccating determining the spread of a bushfire. Due to lack of rainfall, vegetation such as dry grasses, parched native shrubs and other combustible materials build up and become fuel for the fire to burn. Before the Ash Wednesday fires Victoria suffered 10 months severe drought.
The relative humidity also results in the right climatic conditions for a bushfire to occur. If the amount of water vapour in the atmosphere is than 20%, it can cause forest fuels to dry out and become highly flammable. The relative humidity of Victoria was exceedingly low in the months leading to the bushfires. At one stage Melbourne’s relative humidity reached as low as 6% compared to the usual 43%. This factor greatly
contributes to increasing the speed of the fire.
High temperatures are necessary for a fire to occur. Hot air from high temperatures is responsible for helping to lower the moisture content of forest vegetation, making the fuel more flammable. February 1983 was one of the hottest and driest Februarys on record, with temperatures reaching a record 46.1 degrees Celcius.
Wind plays a major role in the spread of fires. High winds provide the fires with oxygen to burn resulting in larger and stronger flames. In addition wind can also cause spot fires by blowing embers downwind. The wind movement on February 16 also resulted in many fires merging.
Weather conditions such as cold fronts also produce severe bushfire conditions. In southern Australia cold fronts are common and dramatically affect bushfires. Figure 2 shows the cold front as it headed towards Victoria on February 16.
When a cold front passes, the wind direction will change about 90 degrees and will also cause very hot, dry winds. Figure 3 and 4 illustrates the cold front changing the direction of the fire, causing the long side of the fire to suddenly become the front.
WHY IS THE LOCATION PRONE
Victoria is prone to the hazard of bushfires because during summer and autumn Victoria experiences hot, dry climate which causes the vegetation to dry out. Victoria’s forests mainly consist of Eucalyptus trees, which contain large amounts of oil making these forests highly flammable. Southern Australia also experiences strong winds in summer, which result in increasing the damage of the fire. Figure 6 on the left shows the areas of Australia that are prone to bushfires.
The impacts of a hazard when it strikes a town or region can be very dramatic. The impacts can be categorised into environmental, economic and social impacts.
The Ash Wednesday fires caused widespread damage to the environment burning over 210,000 square hectares of Victorian land in total and 21,000 in South Australia. The land burnt Dandenong National Park, the Wombat State Forest, pine plantations and the Otways Forest.
Although the Ash Wednesday bushfires regenerated the bushland they caused extensive damage to native habitats and also resulted in the death and injury of many animals. The fires also caused changes to biodiversity levels, high levels of erosion, disrupted the water quality in local streams and waterways and also released thousands of tonnes of carbon emissions into the atmosphere.
Figure 7 shows the CFA rehydrating a koala that survived the fire.
The economic impacts caused by the Ash Wednesday bushfires were very large. It not only affected the local communities but also the whole of Australia. The total cost of property related damage in Victoria was estimated at over $200 million. In addition the damage to valuable timber in state areas and timber plantations was estimated at over $50 million. All together the cost of damage was over $950 million. A large majority of individuals experienced property loss and many were not insured against bushfire therefore lost all their life savings. Even those who were insured did not receive everything back from insurance agencies and had to make do with what they were given.
Figure 8 on the right shows the large areas burnt by the fires
The Ash Wednesday bushfires brought death, destruction and hardship on people’s lives. Many people were not prepared for a bushfire of that degree. It was the biggest fire Victoria had seen and took many by surprise. The number of casualties was 75 including 13 CFA fire-fighters and many more were injured. There was also the loss of over 2,000 residential homes in Victoria and in South Australia 383 more. Figure 9 on the left is a photograph showing a street of houses all burnt down. The impact of the fires was very difficult on individuals, especially the ones the lost friends and family members in the fires. There were also many health problems caused by the fires, both mental and physical. These health problems were caused from stress, smoke inhalation, asthma attacks and the trauma sustained.
“It was just this bloody great force. It wasn’t fire by itself. It wasn’t just the wind. It was something different to that…a monster” was a statement made by John Baxter. The above statement shows how many residents may have reacted or felt about the fires.
To protect Victoria and the environment from another disastrous bushfire, some management strategies need to be implemented. These could include:
* Local residents should remove any fire prone objects in and around the home for example clearing leaves in gutters and raking and discarding dried leaves around fire seasons.
* An education and awareness program could be developed to inform people on the risks on living in fire prone areas. Topics should include how and why people die in bushfires, how to insure their homes against fires and prevention measures.
* A warning system should implemented to warn the community on incoming fires. To supplement this an evacuation drill should be put in place so the local communities know what to do in the case of a bushfire.
* Local communities should become more involved in forest management and conservation to ensure the future protection of the environment for future generations.