Wildfires Flashcards
(29 cards)
What is a wildfire?
An uncontrolled rural fire
What are wildfires in Australia?
Bushfires
What are wildfires in North America?
Brushfires
Types of wildfires:
•Crown fires = Spreads rapidly across the tree canopy which are more likely to be intense and fast-moving
•Surface fires = Burns across surface vegetation which can be low or high
•Ground fires = Burns the ground itself and beneath the ground in layers of organic peat which is slow, smouldering fire with no flame and little smoke
Characteristics of surface fires:
•Most common
•Burn along the forest floor
•Burn leaf litter and fallen branches
•Burn 900°C
•Cool and rapid
•Relatively easy
Favourable vegetation for fires
•Thick undergrowth or closely spaced trees allow it to travel easily. •Eucalyptus and pine contain oils which burn easily, and eucalyptus sheds bark which burns quickly
Favourable fuel characteristics for fires
•Fine, dry material can catch fire and burn easily
•Large amounts of fuel can form a continuous cover helping to burn for longer
Favourable climate and recent weather characteristics for fires
•Rainfall sufficient enough to grow vegetation so plenty of fuel available
•Area with a distinct dry season when rainfall is low for a significant amount of time -> Warm, dry weather causes water to dry up from plants so it’s more flammable
•Strong winds provide more oxygen to help fire burn and spread embers
Favourable fire behaviour for fires
•Creeping fires move across the ground surface fairly slowly
•Running fires spread rapidly and is more intense
•Fires can throw out burning debris and that helps the fire spread and become more intense
Natural causes of fires
•Lightning strikes
•Earthquakes
•Volcanic eruptions
•Lack of precipitation
Human causes of fires
•Train wheels
•Gun shooting
•Powerlines
•Arson
•Campfires
•Cigarettes
•Agriculture fires
What is pre-heating?
Water is expelled from plants by flames. Gases released as temp rises, wood breaks down by pyrolysis
What is flaming combustion?
Wood and hot gas burn fast creating cracks in wood which releases gas, flames, oil and resin. Energy released by convection and radiation. Poor heat conductors
What is glowing combustion?
Wood burns slowly and at lower temperatures. 500°C as fire consumed wood itself, instead of gases by pyrolysis
How do fires spread and increase?
•Gases released e.g. hydrocarbons burn easily
•Lack of precipitation
•Plant material builds up
•Higher temperatures
•Unmanaged forests
•Increased human activity
•Type of vegetation
•Topography
•Wood ash enriches the soil -> Potassium, magnesium and sodium
•Fires can generate their own wind
What is El Niño?
•Cyclic climatic conditions that occur on average every 6-8 years
•Involved warming of Pacific Ocean off west coast of South America
•Leads to global pattern change of temperature and rainfall
•Suffering from floods (possible link between El Niño and CO plumes from wildfires)
Social impacts of wildfires
•Deaths and injuries
•Homes destroyed
•Can destroy powerlines and damage reservoirs, leaving people without electricity or clean water
•People can develop health problems e.g. inhaling smoke
Economic impacts of wildfires
•Can destroy businesses leading to loss of jobs and income
•Insurance premiums increase dramatically
•Cost of fighting wildfires is huge
•Possibly discourage tourists reducing income from them
All disrupting local economy
Political impacts of wildfires
•Pressure on emergency services which may need international aid and assistance
•Temporary evacuations by local and national governments
•Reliance on aid for short and long term relief/recovery
Environmental impacts of wildfires
•Destruction of soil structure and nutrients
•Loss of wildlife habitats and ecosystem disruption
•Atmospheric pollution from particulate matter and toxic gas
•Increase risk of soil erosion and flood risk
•Climate change from reduction in biomass carbon sink
•Stimulate seed germination
•Habitat loss
•Some ecosystems rely on wildfires to clear dead vegetation
Individual short term responses for wildfires
•Fill as many containers with water
•Lawn sprinklers on roof or above ground fuel tanks
•Wet the roof
•Ladder against the side of the house
•Turn on as many lights in the house -> increasing visibility in smoke
•Close windows and doors but leave unlocked
Professional short term responses to wildfires
•Local agencies -> Firefighters, emergency medical services and local police
-Assessment xonducted to determine basic human needs
•Search and rescue, distribution of resources, immediate temporary relocation for displaced individuals
Professional long term responses
•Repair infrastructure and return community to normal operational status
•Post recovery efforts -> assess fire damage, shrubs and soil: which are dependant on fire intensity
•Low intensity = minimal fire damage to small trees without burning all forests and majority of leaves remain on trees
Preparedness for wildfires
•Removal of leaf litter via controlled burning
•Monitoring via satellites
•Educational plans
•Distribute aid
•Emergency supplies
•Fire breaks made
•Build protected homes
