Geography Notes Year 9 – Bushfires
BUSHFIRES – VIVIANNA IP YR 10
Bushfire: the combustion or burning of bush, forest or woodland area.
They occur because of Australias hot, dry climate and the fact that Australia experiences many droughts.
South-eastern Australia includes areas that are prone to the most severe and frequent bushfires in the world.
Strong winds in summer and sudden changes in wind direction can worsen the damage that bushfires cause.
Occur in areas where major forests are found.
Many of Australias native plants burn easily – eucalyptus trees have a high oil content and are highly flammable, the large area of dry grass common in mid to late summer also burn readily.
Can be caused by natural means (lightning strikes) or by humans who act carelessly.
It can either be controlled or can burn out of control (depending on weather conditions – wind, the quality and the dryness of the undergrowth).
4 main factors that lead to the right climatic conditions for bushfires are:
Humidity ( the amount of water vapour present in the atmosphere): very low humidity (less than 20%) causes fuel to dry out and become flammable.
Lack of rainfall: leads to dry vegetation, dead leaves and twigs that become fuel for bushfires.
Wind: air movement provides the oxygen the fire needs to keep burning; stronger winds bring more oxygen and stronger flames and winds also blow small fragments of ignited vegetation (embers) downwind causing small fires and burnt-out areas (spotting).
Temperature: hot air can lower the moisture content of vegetation.
ECONOMIC IMPACTS
Total cost of fire approx $8500million/annum (approx 1.15% of AUS. GDP)
Many individuals lose property and their life savings, as they are not insured against bushfires.
SOCIAL IMPACTS
Approx. 100 fatalities + 3000 injuries/ average each yr.
Loss of homes average 83 homes a year.
Health impacts resulting from stress, smoke inhalation and asthma attacks.
Many individuals have a poor understanding of the risks posed by bushfires and how to preserve their lives and property and as a result may be traumatised.
ENVIRONMENTAL IMPACTS
Broad range of impacts in the biophysical environment.
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