Wildfire hazards are dangerous Flashcards
How fast can wildfires travel in forests?
6.7 mph
How fast can wildfires travel in grasslands?
14 mph
How might a wildfire spread?
Jumping or spotting - winds carry firebrands (hot wood embers) through the air
What can spotting cause?
Hot embers and firebrands to ignite fuels downwind from the fire
In Australian bushfires how far away are spot fires known to occur?
20 kilometres from the fire front
What impacts do large wildfires have on their immediate vicinities?
As air rises as its heated, powerful updrafts will draw in new, cooler air from surrounding area in thermal columns.
Differences in temp and humidity will cause pyrocumulus clouds, strong winds and fire whirls with the force of tornadoes at speeds of more than 50mph
What are pyrocumulus clouds?
Grayish or brown in colour because of the ashes and smoke of the fire
How may the thermal heat from a wildfire effect rocks and boulders?
Through weathering, the heat can rapidly expand a boulder and thermal shock can occur, may cause an object’s structure to fail
What is the ladder effect?
Describes the way a fire moves from ground to the canopy of the forest through a step-by-step process
What is the local distribution of wildfires?
The vegetated areas of Australian Western Cape of South Africa and throughout the dry forests and grasslands of North America and Europe
Where are wildfires common?
In places where climates are moist enough to allow the growth of trees and shrubs, but have extended dry, hot periods
Whats an example of a plant which enhances a fire?
Cistus monspeliensis and Australian Eucalyptus tree
How does the cistus monspeliensis enhance fires?
It has evolved to burn. The fire will mechanically rupture the seeds of Cistus, the smoke and heat will trigger germination of the next generation
How does the Australian Eucalyptus tree enhance wildfires?
It is full of VOCs (Volatile Organic Compounds) that are highly flammable and encourage the fire to develop once they are alight
What is an example of a plant which resists fires?
Pinus Pinea
How does the Pinus Pinea resist wildfires?
It is a passive pyrophyte
What is the frequency of wildfires?
The number of fires are decreasing due to the fact we are able to identify, protect, and response better than ever before
The area affected is increasing - only reasonable answer is global warming
How are wildfires caused?
90% are caused by humans - arson, campfires, cigarettes, burning debris, fireworks
Remaining 10% are started by lightening of lava
What is the El Nino phenomenon?
It dictates weather in Australia and influences the climate
What is the El Nina?
Easterly winds push warm water along the equator, over too the west
The lack of warm water along the coast of America leads to the pull up of cold water to replace the missing warm water (upwelling)
This leaves the coast of America very dry (lack of rising air), unlike Australia, where the warm water evaporates, rising into the air where it cools and condenses, forming clouds
When does the pattern of El Nina reverse?
Every 7 years
What is the El Nino?
The reversal of the El Nina
What is the El Nino phenomenon?
East trade winds weaken, therefore the warm water doesn’t fully get pushed over, subsequently rainfall falls elsewhere, and dry air circulates around where rainfall takes place, leaving the east coast of Australia in risk of drought.
How does conduction spread a fire?
Conduction is the transmission of heat through material/
Fire brands produce ferocious specs of fire embers which conduct bits of fire up to 1km away producing spot fires
How does convection spread a fire?
Through the tendency of hotter and therefore less dense air to rise, and colder, denser air to sink under the influence of gravity, which consequently results in the transfer of heat, causing higher/taller vegetation to ignite producing a ladder effect
How does radiation spread a fire?
Heat is transferred not through contact but thermal radiation, this causes fires to spread even when the fuels don’t sit next to each other
How does fire brands spread a fire?
Bits of burning hot wood that rise and get blown elsewhere. They can cause spot fires away from the initial fire
What is a fire front?
The leading edge of the main fire, the bit of the fire thet is advancing
What is Pyrophytes plants?
Plants which have adapted to tolerate fire “Pyrophyte originates from the Ancient Greek term “pyros” which means fire
What are passive pyrophytes?
Resist the effects of fire, particularly when it passes over quickly and hence can out-compete less resistant plants which are damaged
What are active pyrophytes?
Similar to passive pyrophytes but contain volatile oils and hence encourage the incidence of fires which are beneficial to them
What are “pyrophile” plants?
Plants which require fire to reproduce
How do Eucolyptus tree’s spread fires?
They are evergreen and drop leaves all year round - constant leaf litter
It has exfoliating bark, therefore the tree sheds its bark to the forest floor throughout the year - building up supply of litter which ignites at 200 degrees
Hanging ‘streamers’ enhance the ‘ladder effect’- enabling the fire to build into a crown fire
Seeds open in extreme temperatures and germinate well in the warm ash rich soils
Packed full of VOCs which enhance flammability
What is an example of a wildfire?
Black Saturday 7th Feb - 14th March 2009
How did the human factor of population aid in causing ‘Black Saturday’?
The fact arson was a contributing to the cause, if there wasn’t as many people it may not have happened
How did the human factor of arson aid in causing ‘Black Saturday’?
Arson - he was found guilty - after originally claiming it was an accident - of starting the Churchill fire intentionally, killing 10 people and ruining 150 homes
How did the human factor of logging aid in causing ‘Black Saturday’?
It created canopy openings and this altered microclimatic conditions, increasing the drying of understory vegetation and forest floor
Uncut native forest would generally not burn after less than 30 rainless days but a selectively logged forest would burn after just six to eight days without rain
What does opens on the Pinus Pinea when exposed to a fire?
Hard-coated fire resistant cones
What happens as the Pinus Pinea grows?
It self-prunes the lower branches which helps prevents the fire from travelling at ground level from jumping to the canopy and destroying the tree
What are the environmental primary impacts of wildfires?
Destruction of habitats and ecosystems
Burning of carbon stores
What are the social primary impacts of wildfires?
Loss of life and injury
Displacement
Damage /destruction of structures
What are the economic primary impacts of wildfires?
Disruption of power supplies
Financial loss
Loss of crops and livestock
What are the environmental secondary impacts of wildfires?
Death and injury of animals because of impacts on the food chain
Short term surge of CO2
Atmospheric pollutants from smoking
Water pollution from toxic gas in water
Increasing gas emissions - climate change
What are the social secondary impacts of wildfires?
Atmospheric pollution and smoke
Damage to mobile phone transmitter
Lack of trees and vegetation causes depletion of nutrient stores
What are the economic secondary impacts of wildfires?
Financial loss
Destruction of businesses
Possible need for new employment and income stream
Cost of future preparedness and mitigating strategies
What are the political secondary impacts of wildfires?
Actions of emergency services
Responses of local government
National government
Pressure of local authorities
How many died during the Black Saturday bushfires in 2009?
173
How many were injured during the Black Saturday bushfires in 2009?
414
How many people lost their homes in the Black Saturday bushfires in 2009?
2000
How many hydro electric dams in Melbourne were contaminated with ash?
5
How far did the smoke from the bushfires make it?
To Antarctica
How much was the total cost of the Black Saturday bushfire?
$4.4 billion
How much pastoral was lost due to the Black Saturday bushfire?
62,000
How many tonnes of hay and silage was lost due to the Black Saturday bushfire?
32,000
How does one prepare for wildfires?
Thin tree and bush cover Dispose of debris from thinning Remove dead leaves Stack fire woof away from home Maintain irrigated green belt Mow dry grass USA - red flag warning system,
How does one mitigate for wildfires?
Early detection
NASA is developing drone technology for surveying vast areas - thermal imaging and infrared cameras
Deliberate burning of material ahead of fire
Disaster aid insurance
How does one prevent wildfires?
Controlled burning
Public awareness
Smokey bear
What is smokey bear?
A set of five rules with 96% of Americans recognise
What are smokey bears 5 rules?
Only you can prevent wildfires A,B, C of wildfires - always be careful Never play with matches of lighters Always watch your campfire Make sure your campfire is completely out before you leave it
What is the risk and vulnerability of Victoria?
Its covered with Eucalyptus forests which easily burn
Dry vegetation as temp exceeds 40 degrees
Susceptible to high wind - firebrands
El Nino and IOD -positive
