Monday 25 April 2011

What are the conditions needed?

Australia has a climate that is mostly hot and dry which are the perfect conditions needed for making a bushfire. Bushfires are frequently occurring events during the hotter months of the year and usually have extremely devastating effects.

 Australia is the continent that almost all bushfires occur in. It's geographical location makes the sun very harsh, and the strong winds propel the raging fury.  Low relative humidity, high winds and lack of rain all contribute to increased fire danger. Sunshine and high temperatures will quickly deplete all the moisture out of timber and grass which will cause it to burn furiously. Wind is a major factor to Bushfire speed and intensity because fires need oxygen. When the wind speed increases by double the fire's spread rate quadruples. A lack of rainfall (like during a drought) will even make the heaviest of fuels (like large logs) dry out and become perfect for fuelling a fire.

By world standards, Australia has a very low and unreliable rainfall and the whole continent has suffered from droughts many a time. Droughts create a high fire risk, especially if the drought follows a period of good rain that encourages lush, thick growth
 
But these conditions alone are still not enough to ignite a bushfire. Common causes for bushfires include lightning, arson, accidental ignition from agricultural clearing, campfire, cigarettes and dropped matches, machinery and controlled burn escapes.



Area's affected

Nearly all of Australia can potentially have a bushfire due to weather conditions. but whether there is enough fuel or not to allow the fire to spread is the main issue. Here is a map showing which seasons/weather conditions are best for cultivating a fire.

 Historic Chart Analysis at 11am EDT on "Ash Wednesday", Wed 16th February 1983 showing areas with extreme fire weather.

Historic Chart Analysis at 11am EDT on 7 January 1994, showing areas with extreme fire weather that resulted in serious bushfires in NSW and southern Queensland


Historic Chart Analysis at 8am WST on  4 April 1978 showing areas with extreme fire weather associated with the gales in the aftermath of Tropical Cyclone Alby.





The Impacts of Bushfires on the environment, economy and people and the response from society.

Bushfires are often extremely tragic events. Bushfires have accounted for over 800 deaths in Australia and the total accumulated cost is estimated at $1.6 billion.  More than 10,000 properties have been obliterated. Millions upon millions of trees and other plants are also burnt down but luckily Australian flora has adapted over the years to recover quickly from devastation.  In some eucalypt and banksia species, for example, fire causes seed pods to open, which allows them to germinate. Fire also encourages the growth of new grassland plants.

 Bushfires obviously have a major impact on people, emotionally and physically. If a person get's trapped in a burning forest/house then they may burn/suffocate to death and if a relative of someone dies in a fire then that event will cause major emotional stress.

Bushfires affect the economy but how badly they affect it depend on three main factors. First, where the fire is positioned and what direction it is heading (ie. whether settlements are in it's burning path), How detrimental the fire is and the power and speed behind the response to the fire. If the fire travels through a suburban area, untouched, the overall cost will be incredibly high compared to if the fire just travelled through a bush area. Replacement funds can come from many various sources including the government, insurance agencies and public donation


Other than the obvious loss in housing and businesses, economic impacts are seen in:

  • A loss of income for farmers if their livestock or land has been affected by the fires
  • A potential loss of money from the tourism industry
  • Some people may move away from the bushfire affected area, so they are no longer contributing to the economy of the region
Hosting local charity events is a usual response from society and is usually very effective. This can be achieved through many different methods. For example, some local residents may go door knocking for money, cook some food to sell, volunteer to cleanup and rescue, and donate.

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