Wilfires Flashcards
The nature and cause of wildfires ….
Explain the natural causes of wildfires?
For a natural wildfire to occur and spread, two things are needed, an ignition source, most commonly lightning. Climate will affect the frequency of electrical storms, particularly in areas where there is hardly any rainfall. Fuel is also needed in sufficient quantities and it needs to be dry enough. Climate affects the frequency of drought and the vegetation that grows in the area.
Explain the human causes of wildfire?
increasingly fires are the result of human intervention, particularly those which occur in and around settlements. Such fires are started by falling power lines, carelessly discarded cigarettes, camp fires, barbecues and agricultural fires (controlled burning) which get out of hand. Greater access to wild areas by tourists has increased the dangers of fires from the reasons above.
What will affect the nature of the fire and why?
The nature of the fire will depend upon the types of plants involved, strength of winds, topography of the area in question and the behaviour of the fire itself. Once the vegetation has dried out, the nature of the fire will depend largely upon the wind, as the largest fires occur in dry windy weather with low humidity.
Ignition
Atmospheric conditions
Resources to burn
The distribution of wildfires ….
areas that are most susceptible are those with a Mediterranean and tropical wet/dry season (savanna ) climates. In Mediterranean climates (Southern Europe, California, parts of Australia), winter rainfall encourages vegetation growth but hot dry summers with occasional thunder storms, result in a fire hazard. A similar pattern occurs in Savanna regions (northern Florida, north eastern India + tropical regions of Africa and South America) although it is the summers that are wet and winters that are dry.
The magnitude and frequency……
Primary effects …..
loss of crops, timber and livestock (huge impact on timber producing areas and the loss of trees will take many years to replace)
Loss of life
Loss of property (large numbers of people left homeless
Loss of wildlife
Release of toxic gas and particles (fire related air pollution)
Damage to soil structures and nutrient content
Secondary effects …..secondary
evacuation: many people will flee from the affected area and often not be allowed back to the affected area for a long time. Emergency shelters / accommodation will have to be found along with food
Increased flood risk: in certain environments, where rain comes in heavy bursts, the loss of so much vegetation, and the consequent decrease in interception, can lead to increased flooding
Environmental effects ….
Land destroyed
Loss of habitat for animals
Water pollution from debris
Pollution from gas emissions
Political effects ….
Social effects ….
Economic effects …
Explain some management/ responses strategies before the hazard
Vegetation management?
clearing areas between trees and other vegetation ahead of a wildfire event to create firebreaks, which help prevent the spread of the fire.
Built environment management?
using fire resistant materials to build houses and extensions or outbuildings
Clearing flammable materials and vegetation within 10m of building to create fire resistant zones
Computer modelling
this has been employed to understand and predict the fires behaviour. It evolves studying the ways in which fires behave to comprehend and predict fire behaviour
Education
in areas affected by fires.Governments often release guidance on how to prepare for such an event by familiarisation with evacuation routes, clearing flammable materials and vegetation within 10 m of buildings to create a fire resistance zones, creating a fireproof safe place at home for all important paper documents,putting together a bag essential for life away from home and signing up to be aware of fire warning systems produced.
Warning systems
Signing up and being aware of fire warning systems produced (e.g. by the state of California and the federal weather service)
Insurance
taking out of sufficient insurance to cover and replace everything that could be lost including the house itself
Management strategies / responses to reduce impact of wildfires?
Ecological restoration
(Strengths?)
prescribed burning, low intensity and stops overpopulation of vegetation, allow decomposition
Low cost -> large scale
Sustainable as works with natural fires
Reduces fuel so minimises scale of fire
(Weaknesses)
lots of smoke in fire season
Public opposition in practise
Can lead to law suits
(Rank)
most effective
Low cost
Large scale
People can be persuaded
Makes fires less intense
Thinning
(Strengths?)
hyper local fuel reduction in scale of fire
(Weaknesses?)
not effective in highest winds, when ultra dry (embers can travel long distances)
Unpopular as woods look scarse.
High cost + constant maintenance required
(Rank)
second most effective
Used if you can convince community of ecological restoration
Expensive
Not always effective
Community preparedness
(Strengths?)
orderly evacuation can save lives
Homeowners can reduce the risk around their homes
(Weaknesses?)
high ongoing budget required
Evacuations can cause panic
Not everyone will comply
Poorly communicated
People can be complacent
(Rank)
least effective , but still effective
Education can buy consensus for other management
Better prepared, reduce the risk of loss of life
What management strategies are used during the event?
spraying the fire with water and chemicals from both the ground and the air is costly. Firefighters also work on the ground by bulldozing large breaks in the vegetation preventing the fires jumping in certain directions, retardants are used to slow the pace of the of the wildfire and often sprayed on fires in areas which off inaccessible when human safety and structures are endangered
Wild fire case study name:
CampFire, California
CampFire Facts:
- characteristics of place/hazard
- primary / secondary effects
- risk/ vulnerbility
- long / short term response
Characteristic of place
- prolonged drought in area
- populated urban areas spread into forested area
Characteristic of hazards
- inaccessible to put out early ignition
- started underneath a 100 yr old high voltage electricity tower that was not turned off despite winds
- failed equipment brought the power line in contact with the steel tower.
- most expensive disaster worldwide in 2018
Primary effects
- 85 dead
- 50,000 people evacuated
- 1,500,000 acres destroyed
- 7,000 homes destroyed
Secondary effects
- cost 16.5 billion dollars
- took weeks to identify the dead
- smoke inhalation and pollution
- insurnace claims (insurance raised)
- water pollution / contamination
Risk
- 100 yrs of fire suppression which lead to the forest being dense and widespread
- high winds, dry vegetation
- densely populated urban areas that spread into forested areas
Vulnerability
- wooden houses
- prolonged drought, dry vegetation
- however state is rich, so less economically vulernable
Long term response
- investigation into criminal charges ($10.5bn fine)
- power company now shut off power on red flag days
- updated evacuation plan, but hindered by infrastructure
Short term response
- shelters set up
- thousands raise from gov, ngos etc
- 5000 fire fighters
