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Hazards - Wildfires - Coggle Diagram
Hazards - Wildfires
Wildfires are unwanted, uncontrolled land fires. They are known as bushfires in Australia and brushfires in the USA. Wildfires are a natural process in many ecosystems.
Types of wildfire: -Fire behaviour will determine what type of wildfire occurs.
-There are three types of wildfire; ground fire, surface fire and crown fire and one, two or all of these types of fire may make up a fire event.
-Surface fires burn along the forest floor.
-Ground fires burn organic matter in the soil, they are slow burning and can smoulder for long periods.
-Crown fires burn through the canopy, they are the most dangerous and difficult to control.
Benefits of wildfires: -Regular occurrence of small fires can reduce the amount of fuel build-up. Therefore they can lower the likelihood of more and more dangerous fires.
-Fires can remove alien plants that compete with native species for nutrients and space.
-The ashes that remain after a fire often add nutrients to the soil.
-Can provide a way of controlling insect pests by killing off older or diseased trees and leaving younger/healthier trees.
Large scale fires are major events that can cause widespread destruction and kill. Ground temperatures can rise above 1000 degrees and at higher levels fires can spread rapidly through the canopy.
Wildfires are quite widespread all over the world but there are no wildfires in desserts. There are high fire counts along the Tropic of Capricorn, such as in Brazil and Australia.
Causes of wildfires:
-Lightning strikes can spark fires.
-In mining areas, underground fires can burn into the coal and peat above and set the surface on fire.
-Broken glass left as litter can act as a magnifier which can set dry grass on fire.
Sparks from trains can cause the land near tracks to burn.
-Burning is often used to clear forest for new use of the land.
-Discarded cigarettes can ignite dry vegetation easily.
-Campfires are often left unattended or not put out properly.
-Deliberate burning of moorland for farming can get out of control.
Impacts of Wildfires
Environmental impacts:
-Loss of habitats.
-Carbon dioxide released into the atmosphere.
-Can regenerate a forest.
-Worse or better soil quality.
-Reduces fuel supply.
-Can get rid of diseased trees.
Social impacts: -Loss of houses. -Deaths and injuries. Evacuation. -Potential job loss. -Health problems. -Disruption to power supplies. -Behavioural adaptations based on wildfire experiences. -Lack of communication.
Economic impacts:
-Farmland destroyed.
-Job loss.
-Businesses destroyed.
-Insurance.
-Damage to structures.
-Cost of rebuilding.
-Cost of future preparedness and mitigation strategies.
Political impacts:
-Instability.
-Distrust with the government.
-Lack of response by the government.
-Change in political views.
-Actions of emergency services.
-Decisions about replanting forests.
-Review laws.
Management
Preparedness:
-Community preparedness is the form of early detection and suspension of wildfires is an important element in reducing the speed of wildfires.
-Warnings are released through social media.
-A red flag warning is the highest level of warning.
-A fire weather watch is issued when such weather conditions could exist in the next 24-48 hours.
-People may be able to establish firebreaks around their property.
Mitigation: -Involves reducing the severity of an event by direct intervention as well as support following a disaster.
-Thermal detectors to detect thermal variation.
-Cameras are used to detect early ignition of fires.
-NASA is developing drone technology.
Prevention:
-Controlled burning reduces the amount of fuel.
-Public awareness is important, especially on campsites and public areas.
-Public signs.
Adaptation: -Adaptation involves learning to live with the threat of wildfires and letting them take their course.
-Buildings need to be relatively simple, cheap and made of natural products that will not cause pollution if they burn down.
Wildfire Spread
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The Landscape
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The process of heat transfer is influenced by topography, because heat rises and winds travel faster going uphill.
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