HAZARDS - wildfires Flashcards
wildfires
unplanned, unwanted wild land fires including unauthorised human induced fires
controlled fires
fires started by humans which are beneficial. eg) cooking, agriculture, remove fuel in a safe way to prevent wildfires.
distribution
Australia, Africa, South and North America.
wildfires in Australia
grassland, flat, dry and warm = all yr round
wildfires in Africa
dry grassland = FIRE CONTINENT
wildfires in South America
slash and burn, pastoral
wildfires in North America
forest and agriculture - prescribed (controlled fires)
three factors needed to start a fire
oxygen, fuel and heat
surface fires
most common - burns the leaf litter 900*c cools quickly and easiest to control
ground fires
organic matter in soil = slow smouldering fire at 540*c
long periods
crown fires
burns the top foliage layer - canopy.
Loose bark = fire travels up trunk
excess temp of 1100*C
most intense and difficult to contain
vegetation type that favours intense widfires
close together
trees that contain lots of oil (eucalyptus and pine)
loose bark/ foliage
fuel characteristics
dry, fine material
large amounts forming continuous cover
climate and recent weather
sufficient rainfall to allow for plenty of vegetation cover
dry season to allow vegetation to dry
strong winds = more O2 to help the fire burn and spread
low humidity
fire behaviour
creeping - slowly across the ground
running- spreads rapidly and more intensely
firebrands/ spot fires - flying debris spreading the fire
wildfire season in the US
summer = drier fuel
wildfire season in Africa
dry dusty north eastern trade winds Harmatten winds
November to March
human causes of wildfires
campfires, smoking, arson, glass
what % of wildfires are due to arsen?
30%
Natural causes of wildfires
lightning, volcanoes
land topography
steeper slopes = faster travel of fire due to wind being pushed upwards
also heat and smoke rise = reaches more fuel
what % humidity increases the risk of a wildfire
below 7%
% of fires caused by lightning
10%
santa ana winds
desert winds from the mountains. compressed and warmed so they have very low moisture. blow over Australia creating perfect conditions for fires
weather phenomenon that improve the conditions for a wildfire
el niño and la niña (every 3-7 yrs) and climate change
el nino
warming phase of sea surface temp ENSO
el nino southern oscillation
la nina
cooling phase of sea surface temp
positive impacts
insect pest control removes non -native species ash = nutrients encourages growth = + sunlight for emergent layers some fire dependent species
adaptions of trees to wildfires
thick bark, high moisture content, underground storage (+++roots)
baobab tree
thick fibrous bark lives with burns
banksia tree
50% survive wildfires
thick bark
lignotubers (swollen base) re-sprouts
fire triggers seed release.
negative local impacts
life, property, transport, power, businesses
negative impacts on the watershed
habitat, weather, soil erosion, crops, co2 release
negative regional impacts
health, tourism, air quality
negative national impacts
transport, cost of mitigation, development
Negative global impacts
air travel, crops,
eg) jasmine revolution due to increased crop prices and fuel prices. North Africa - tunisia
mitigation strategies
fire, police and medical services
fire breaks - clear areas of fuel
beating the flames - removes co2
spraying with water and chemicals
adaptions
defensible space
education and awareness
early fire detection
how to protect homes
incombustible barriers (concrete) remove fuel fire resistant roofing roll down metal fire doors and windows sprinklers in gardens
fire detection tech
satellites, infrared sensors, cameras and drones
prevention
slash and burn - removes fuel
forecast = effective decision making time
volunteer debris clearing
smoke jumpers and vehicles with water and chemicals
preparedness
fire bans clear property of ignitable materials ladder to roof fill water containers irrigate land often fire retardants close by home insurance website with information and protocol
