✅HAZARDS 3.1.5.6 - Fires in Nature Flashcards
What is a wildfire?
A bushfire or rural fire which is uncontrollable and spreading
What are the three things needed for fires to burn?
Heat, Fuel and Oxygen
What can sources of fuel include?
Trees Logs Dry Grass Petrol Aerosols Leaves
What can sources of heat include?
Cigarette ends Matches Barbecues The sun Electrical storms Broken glass Arson
How can the seasons affect the likelihood of wildfires?
The drier and windier the season, the more likely the wildfire
What is the most common cause of wildfire?
Arson
Which factors can worsen wildfires?
Dry vegetation Ladder fuels Hilly areas Homes with wooden/timber cladding Flammable fertilisers
How can wildfires be prevented?
Remove ladder fuels Control of vegetation Natural 'breaks' or borders Removal of fuel sources Burn off crops after harvest
What phenomenon can make conditions warmer and drier?
El Nino and the Indian Ocean Dipole
What is El Nino?
A climate cycle in the Pacific Ocean with a global impact on weather
How does vegetation type affect wildfires?
Water strong plants eg Cacti are much harder to burn while Eucalyptus use the nutrients released from ash and the additional light from surrounding vegetation being burned, so promote wildfire
How can wildfires be mitigated against?
In countries such as Australia and the US, which are prone to fires, organisations produce advice for residents and some states such as Colorado provide residents with a set of guidelines
What are some of the guidelines set in Colorado?
Reduce fuels around the home
Mow grasses and weeds often, to shorter than 6 inches
Use fire resistant materials in the house
Dispose of any excess accumulation of logs
What is the most popular wildfire education campaign in the US?
Smokey Bear
What are the five rules in the Smokey Bear song?
Only you can prevent wildfires Always be careful with fire Never play with matches or lighters Always watch your campfire Make sure your campfire is out before leaving it
How effective has Smokey Bear been?
It was launched in 1944 and has since been popular with children and adults, teaching the effect of wildfire on the environment. The success has largely been down to the character.
What do NFPA do in the US?
The National Fire Protection Agency runs fire community preparedness days annually to help reduce fuels and educate communities
How can wildfires be detected?
Using traditional manned lookout towers, which can be unreliable and require 24 hour surveillance, or more recently, computer based video analysis which can automatically produce an alert
What does the law state in California?
The residents must clear out all flammable materials such as bush or vegetation around 100ft of the property to create defensible space
What does the law state in Scotland?
The any open fires must be kept under control and must not be lit in prolonged dry periods in areas such as grasslands or forests
Crown fires
Burn up trees the entire length, most intense and dangerous
Up to 1,100°C
Surface Fires
Burn only surface litter
Easiest to put out
900°C
Ground Fires
AKA underground or subsurface fires
occur in deep accumulations of humus, peat, etc.
Very slow, hard to put out
Can smoulder underground in winter and emerge in spring
540°C
How vegetation affects wildfires
Denser, drier, taller = more flammable
Some vegetation has flammable sap like eucalyptus and acacia
How climate affects wildfires
Dry (under 7% humidity) and windy for more fires
Temporal Variation, like El Niño (wet S American, dry SE Asian, warmer North America as jet streams head south) can make conditions more favourable
How topography effects wildfires
Air from mountains gets compressed and warmed, so less humid, dries out vegetation.
Fires travel faster upwards than forwards, so hills = faster travel
Australian Wildfires Dec 2019- Jan 2020
Positive Indian Ocean Dipole caused temps to rise to 41°C in Australia
Positive effects of wildfires
Some plants are adapted against fires, pyrophytic plants, like Baobab Tree with resistant bark
Clearing vegetation makes way for new grass, breaks down vegetation into nutrients for soil
How fires impact soil and land
Can damage soil structure and nutrient content
Like in Georgia, US, 2017, 55000m^2 damaged
LT, less evapotranspiration, less rain
How wildfires impact health
Breathing problems
in SE Asia, 1997/8 fires caused 60 000 to need hospital treatment for this
Example of wildfires emergency response
Greece 2007, 9000 firefighters used to cover 200,000 hectares of devastated land
