Ash Wednesday 1983 is now one of Australia's most well-known bushfire events. Fires swept across Victoria and South Australia, killing 75 people and causing widespread damage
Victoria's natural environments are some of the most fire-prone areas in the world. High temperatures and limited summer rainfall produce conditions of very high fire danger in Victoria's eucalypt forests.
Sudden strong wind changes that hamper efforts to control fires are also common. Bushfire danger becomes serious in some parts of Victoria every few years.
Bushfires as severe as the Ash Wednesday fires however, appear to occur six to ten times a century.
Over 100 fires started on February 16 1983, the day now known as Ash Wednesday.
Lead up to Ash Wednesday
Prior to 16 February 1983, most of Victoria had experienced a drought lasting 10 months or more.
Rainfall over winter and spring was very low, and summer rainfall for Victoria was up to 75 per cent less than in previous years. Low rainfalls meant that there was little moisture in the soil and water supplies in many places were almost dry.
The moisture in the air, called the ‘relative humidity’, was also very low.
Bushfires require fuel such as dry leaves, twigs and other vegetation matter to keep burning and across Victoria, this fuel was very dry, due to the weather conditions, including the low humidity. The forest vegetation in valleys and gullies, which is normally moist in summer, was also very dry.
Getting ready for the fire season
Hot and dry weather towards the end of 1982 gave firefighters an early warning of what might lie ahead.
The earliest total fire ban day ever declared up to that point in time occurred on 24 November 1982.
The Victorian Government firefighting agencies employed extra staff and organised for additional equipment and aircraft to be ready for firefighting over summer.
The first big bushfire occurred on November 25th 1982 and was followed by large fires on 3rd and 13th December 1982, 8th January and 1st February 1983.
By 16th February, Victoria had experienced many very dry, hot days. February 1983 was one of the hottest and driest Februarys on record.
Large areas of land were dry due to the drought. Strong winds lifted 200,000 tonnes of dried soil from the ground and created a huge dust storm across southern Australia on 9 February 1983.
The dust combined with smoke from burning fires and reduced visibility, making firefighting very difficult. The dust cloud was so large and thick it blocked out the sun in Melbourne and gave people little warning of approaching bushfires.
Clear skies and rising temperatures were observed on the morning of Ash Wednesday, 16 February 1983. A front (or band) of cold air was located in the Great Australian Bight off the coast of South Australia. The front caused the hot air in the centre of Australia to be drawn southwards, creating a hot, dry northerly wind over Victoria.
Temperatures in many places rose to over 40 degrees Celsius and the air moisture, or relative humidity, dropped to below 15 per cent. By comparison, the average humidity on a summer's day in Melbourne is 43 per cent.
Many bushfires were reported in the early to middle afternoon and were well established by the hottest and driest part of the day.
Towards late afternoon, the front moved inland and the northerly winds became much stronger. The winds were pushing the fires in a southerly direction creating long, narrow fires.
Many spot fires, caused by burning material blown ahead of the main fire, developed. In many cases, spot fires spread quickly and joined to form a large fire ahead of the main fire. This made the bushfires more severe, and made it difficult for firefighters to control the fires.
After the wind change
The wind change moved through south-west Victoria by early evening. This was disastrous as the westerly winds caused the fires to change direction and size. Prior to the wind change, the fires had been relatively long and thin, with a narrow head, or front. After the wind change, the long side of the fire then became the head, or front, of the fire, burning across a much wider front.
The wind change also caused fires to merge, like the Cudgee/Ballangeich fire near Warrnambool. Firefighters had many problems trying to control these large bushfires. Most of the losses of life and property occurred in the hour following the wind change.
Due to the large numbers of fires burning on Ash Wednesday, many parts of Victoria suffered damage.
Nine of the fires in Victoria were greater than 150 hectares in size. Eight areas of Victoria were considered to be severely affected – these areas are summarised in the following table.
|East Trentham/Mt Macedon||29,500||7||628|
|Belgrave Heights/Upper Beaconsfield||9,200||21||238|
Public land affected by the fires
Areas of public land affected by the fires include the Dandenong Ranges National Park, the Wombat State forest and the Otways forest. Approximately 82,500 hectares of public land, and over 120,000 hectares of private land were burned.
In total, the 1982–83 summer saw some 486,030 hectares of parks and forests burned. The following map shows the areas impacted by all fires on public land in 1983, including the Ash Wednesday fires of 16 February.
The causes of the Ash Wednesday fires include sparks caused by clashing of electricity power lines, tree branches connecting with power lines, deliberately lit fires and other causes that were not identified.
Over 16,000 firefighters attended the Ash Wednesday fires, including park and forest firefighters and Country Fire Authority volunteers. Also involved and assisting in firefighting the fires were 1,000 police, 500 defence force personnel and many local residents. A variety of equipment was used to fight the fires, including 400 vehicles (fire-trucks, water tankers and dozers), 11 helicopters and 14 fixed wing aircraft.
The Victorian fires burned a total of around 210,000 hectares. There were 47 lives lost in Victoria and 2,080 homes were burned. Many businesses, stores, equipment, machinery, stock and other private assets were also lost. The total cost of the property related damage in Victoria was estimated to be over $200 million. See also report 88 at fire and adaptive management publications).
The fires damaged valuable timber in State forests with losses of around $50 million. Park and forest offices and firefighting equipment were lost. The fires burned the vegetation that protects the soil. After the fires, there was further damage through soil erosion affecting streams and water catchments.
Research report 20 describes the fire near Deans Marsh in the Otway's in south west Victoria on Ash Wednesday. The report discusses aspects of the fire's behaviour and includes a map of how the fire spread during the day. See fire and adaptive management publications.
South Australian Ash Wednesday fires
The South Australia fires burned 208,000 hectares in the Adelaide Hills and in farming country in the south-east of the state. In addition, 21,000 hectares of pine plantations were destroyed. Twenty-eight lives and 383 houses were lost. The total cost of the damage to private property in South Australia was also estimated to be more than $200 million.