Wildfires Flashcards
(31 cards)
What are the conditions which favour intense wildfires?
- Vegatation type
- Fuel characteristics
- Climate and recent weather
- Fire behaviour
How does vegetation type influence wildfires?
- Thick vegetation or closely spaced trees enable fire to travel fast
- Eucalyptus contains lots of oils which burn quickly
- Eucalyptus trees shed trips of bark which also helps fire spread
How do fuel characteristics influence wildfires?
- Fine and dry material catch fire and burn easier
- Large amounts of fuel with large % cover enables fire to burn for longer and spread
How does the climate and recent weather influence wildfires ?
- High rainfall means vegetation growth which increases supply of fuel
- Distinct dry season with low rainfall, warm dry weather causes water in vegetation to dry up meaning plant is more flammable
- High strong winds provide more oxygen to intensify and spread fire
How does fire behaviour influence wildfires?
Creeping vs running fire which is more intense with a rapid spread. FIREBRANDS are burning debris thrown out by a fire helping it to spread
Define wildfire
An uncontrolled fire
What are the 3 types of fire ?
- Ground fire: ground itself burns e.g. peat and tree roots. Slow fire with no flame and little smoke
- Surface fire: Leaf litter and low lying vegetation burn. Can be low or high intensity
- Crown fire: Rapid movement through canopy. Intense and fast moving
LADDER EFFECT - Process of fire moving from forest floor to tree canopy
What are the 3 conditions needed for ignition of a fire ?
- Fuel
- Oxygen
- Heat source
Give 2 natural causes of wildfires
- Lightning if it occurs without much rain present
- Volcanic eruptions produce hot lava, ash or gas which ignites fires
Give 2 human causes of wildfires
- Uncontrolled campfires in vulnerable areas
- Arson
Give a prevention strategy as a long term response to wildfires
- Education on the risks of using campfires in vulnerable areas
Give a preparedness strategy as a long term response to wildfires
Households having an emergency plan with emergency supplies to escape wildfires
Give adaptation strategies as long term responses to wildfires
- Using non flammable building materials
- Creating fire breaks in trees around settlements to control fire spread
- Planting pyrophytic vegetation which is adapted to tolerate fire as high moisture content
What is el nino ?
A cyclic climatic event which occurs every 6-8 years and causes warming of Pacific ocean and affects global patterns of temperature and precipitation
What is the Indian ocean dipole ?
An ocean atmospheric phenomenon affecting climates of countries surrounding Indian ocean. Decreases rainfall over Central and Southern Australia, increasing the risk of wildfires
Explain the changing distribution of wildfires
- Every continent has favorable conditions except Antarctica
- Wildfire risk increases proportionally to population increase
- More powerlines and use of machinery
- More vulnerable areas due to climate change
How are wildfires part of a global positive feedback loop?
- Burning increases atmospheric CO2 as stores are released, enhancing the greenhouse effect and creating a positive feedback loop which increases temperatures and increases likelihood of wildfires
Where do wildfires occur ?
Every continent except Antarctica
Why is the risk of wildfires increasing other than climate change ?
Populations grow and move to rural areas and there is greater opportunity for ignition with power lines/ machinery and arson
What is the speed, direction , movement/ behaviour of fire dependent on
Type of fuel, climate characteristic, local topography, vegetation type and recent weather
What happens in Eastern Australia (temporal)
Migrates from the North in the spring to the South in Autumn reflecting variations in rainfall
What factor can determine the speed of movement and rate of spread of a fire ?
Wind strength/ prevailing wind
What are the most vulnerable areas to wildfires ?
‘Wildland-urban-interfaces’ such as LA
Give the statistic about the angel of slope and spread of fires
Fires on a 20 degree slope advance 4x the rate faster than fires on level ground
