Wildfires Flashcards
Wildfire
An uncontrolled or hazardous fire
Crown fire
hottest at 1100^o, most intesne and most difficult to contain
Surface fire
Most common, temps reach of 900^o, easy to control
Ground fire
Burns peat, spread slowly 540^o for a longer period of time
Convection column
The vertical rising column of smoke, ash and particulates caused by the fire
Ladder effect
Moves fire from surface to crown via tree bark
What are the other names for wildfires? And where?
Bushfires- used in Australia
Brushfires - used in North America
What are the three conditions that favour wildfires?
- Vegetation (Living or non living)
- Climate and weather
- Ignition (Natural or human)
El nino
What are conditions like in a normal year
What are conditions like in a el nino year
The indian ocean dipole
The Indian Ocean Dipole (IOD), is an irregular oscillation of sea surface temperatures in which the western Indian Ocean becomes alternately warmer (positive phase) and then colder (negative phase) than the eastern part of the ocean.
Points for climate change increasing the liklehood of wildfires
What are the human and natural causes of ignition
Human:
* * Risk has increased as populations move to rural areas and are most common in the urban-rural periphery
* Collapsing powerlines
* Agricultural fires
* Arson
* Discarded cigarettes
* Uncontrolled campfires and bbqs (approx 90% of causes in the usa)
* Forest clearence and deforestation e.g. The Amazon
* Scrub vegetation inbetween low-density buildings in areas such as LA exposes people to the fire risk
Physical/natural:
* Lightning - most common cause
* Volcanic eruptions - debris
* Sparks from rockfalls
Main causes of wildfires in the USA?
- In the usa 54% of wildfires are ignited by humans and 46% by lightning
- Forest fires have a number of causes - some natural and some caused by human agency
- Drought and heatwaves caused by high pressure systems e.g. california
- Poor forest management which allows shrubs and leaf litter to increase amount of fuel avaliable
- Changes in culture/woodland management e.g. historically native american people and indigneous people in australia practised controlled burning called firestick farming to manage forest fires and create land for grazing and cultivation - this removed fuel and reduced the liklehood of lightning causing wildfires - this is less widely practiced to do so
What is the local and global distribution of wildfires?
Local:
* Rural-urban fringes (near settlements)
Global:
* NA- cali (la), florida and canada
* SA - amazon basin
* Australia
* Southern Europe- spain, italy, greece, canary islands
* Northern Europe - UK
* Regions with semi-arid enviroment - suspectible to droughts
Topography
Topography= the form and features of the local surface (slopes/valleys)
* The process of heat transfer works more effectivley on heating materials that are above the fire vertically = wildfires move more quickly up a slope than on a level surface
* The steeper the slope the more quickly the wildfires travel
* Fires on a slope of 20o or more move 4x more quickly than flat ground
* Burning fragments of vegetation (firebands) can roll down slopes and start new fires away from the fire front
Heat transfer process
Radiation, conduction and convection) Preheat vegetation ahead of flames preparing them for ignition and spread of flames - most effective at preheating material that is above the fire - causing advances of the firefront vertically why fires advance more rapildy up a slope than on level ground
E.g. Austrlia 20 o slope spreads 4x faster than on level ground
Human causes of ignition?
- Risk has increased as populations move to rural areas and are most common in the urban-rural periphery
- Collapsing power lines
- Agricultural fires
- Arsan
- Discarded cigarettes
- Uncontrolled campfires and bbqs (approx 90%)
- Forest clearence/ deforestation e.g. the amazon
- Scrub vegetation in beteween low density buildings in areas such as LA exposes people to the fire risk
Natural causes of ignition?
- Lightning - most common cause
- Volcanic eruptions - debris
- Sparks from rockfalls
Local distribution of wildfires
Rural-urban fringes (near settlements)
Global distribution of wildfires
- NA - Cali, florida, canada
- SA - Amazon Basin
- SE Asia - Indonesia
- Australia
- Southern Europe - Spain, Italy, Greece, Canary Islands
- Northen Europe - UK
- Regions with semi-arid enviroment - susceptible to drought
Local impact of wildfires
Risk to life
Damage to property
Disruption to transport
Landscape/watershed impact of wf
Soil erosion
Loss of crops
Reduction in water quality
Loss of habitat
Regional scale impact of wf
Health effects
Reduced air quality
Impact on tourism
National scale impact of wf
Government costs for fire risk mitigation
Development
Stopping enviromental damage
Global scale impact of wf
Temporary changes to weather patterns
Disturbance to air travel
Primary and secondary impacts of wf
Primary:
* Destruction of habitats and ecosystems
* Death and injury of animals which impacts on food cahins and food webs
* Short tem surge of co2 due to the burning of carbon stores (TREES)
* Atmospheric pollution resulting from smoke and water pollution as toxic ash gets washed into water courses
Secondary:
* Lack of trees and vegetation leads to depletion of nutrient stores, increased leaching and increased risk of flooding
* Increases co2 emissions lead to an impact on ghe and cc
* Effects on ecosystem development - secondary succesion
P
Primary and secondary social impacts
Primary:
* Loss of life and injury
* Displacement - people being forced to temporarily live elsewhere
* Disruption to power supplies if powerlines are damagrd by strong winds
* Damage to mobile phone stations and telephone exchanges affecting communications
Secondary:
* Possible need for new employment and income stream
* Behaviourial adaptations based on wildfire experience - people may have to abibe by new rules and regulations
Primary and secondary economic impacts
Primary:
* Damage abd destrictuion of structures (homes, public buildings, schools, fences and field boundaries
* Financial loss (loss of earnings, damage costs
* Destruction of businessess
* Loss of crops and live stock
Secondary:
* Costs of rebuilding or possible relocation
* Replacement of farm infrastructure, crops, fruits,livestock, trees
* Costs of future preparedness and mitigation stratergies
Primary and secondary political impacts
Primary:
* Action of emergency services
* Response of local and national government (state of emergency)
* Pressure on local authorities and emergency services to coordinate and prioritise repsones in immediate aftermath
Secondary:
* Develop stratergies for preparedness and mitigation
* Decisions about replanting forests, compensation, future regulations etc
* Review law/advice regarding use of countryside for leisure
Impact on soil eorison and water
Synoptic link to water cycle
- One secondary impact is increased risk of soil erosion and landslides
- Wildfires destroy forest canopies so rainfall hits the ground w/o being intercepted
- Where soil is eroded it is washed into river channels and has a negative impact on aquatic ecosystems
- Sediment eroded by rainfall is deposited in reserviors reducing the capacity of the storage system
- Approx 65% of water supply in western usa orginates in watersheds that are vulnerable to wildfires
Wildfires and global systems
- Local ecosystems may be affected with habitats destroyed, animals killed or displaced and soil nutrient stores depleted
- Toxic ash can wash into water courses adversely affecting aquatic ecosystems the relative significance of transfer processess such as surface run off, evaporation and infiltration
- At local scale, nutrient cycles will be impacted by as biomass and litter stores are burned
- Burning will release carbon stored in trees, plants and peat This will increase the amount of co2 in the atmosphere, enhancing the ghe and creating a positive feedback loop as increased temps will increase the liklehoods of wildfires
- Wildfires will affect the development of vegetation sucession, causing secondary succesion to be initiated in forests and scrubland
- Human systems associated with rural enviroments may also be affected by wildfires
Benefits of wildfires
- Remove dead and decaying matter, harful insects or diseased plants from forest floor
- Loss of trees increases sunlight which allows other plants to grow
- Burnt organic matter releases nutrients into the soil which in turn ecnourages new plant growth
- Some plants such as bouglas fir need fire for seed germination
Prepare
Increasing awareness and taking action to reduce the impact
Stratergies of preparation
Education
Community action
Computer modelling
Education as preparation stratergy
- In areas affected by fires, governments often produce comprehensive guidance to help authorires and people prepare for hazards
- Education routes - people to familarise with routes and roads
- Signing up and being aware of fire warning systems provided by state and federal weather systems
- A red flag warning is issued when weather conditions for extreme fire behaviour may be met within the next 24h - highest level of warning and during this time residents are urged to excerise extreme caution
- A fire weather watch is issued when such weather conditions could exisist in next 24-48h
- Daily fire warnings via social media and visible signposting within rural communities and fire bans may be introduced
- Prepare bags with basic essentials, designating a room in the house that can be shut off from outside air when smokey conditions prevail and use air filters to prevent indoor air pollution
- Creating fire proof safe place for important belongings - storing digital docs on cloud storage using fire resistant materials to build house extensions or outhousing, clearing vegetation and flammable mateirals within 10m of the building to create fire resistant zones, insurance covers
Community action as preparation stratergy
- Early detection and suppression of wildfires, reduce the spread and impacts of wildfires
- Rural volunteer firefighthing schemes
- Community education programmes in victoria austrlia - community fireguard
- Create defensible space around property - establish firebreaks such as mowing dry grass, maintain irrigated greenbelt, remove timbs, leaves and other litter, prune branches to 10ft above the ground , trim branches, clean roof gutters, trim tree and bush cover, dispose debris left from trimming stack firewood away from house, reduce density of sorrounding forest - However firefronts can jump 30ft
Computer modelling as preparation stratergy
- Understand and predict fire behaviour
Mitigate
Reducing the severity of an event by direct intervention as well as support following the disaster
Stratergies for mitigation
Education
Managing the vegetation
Sattelite and thermal imagery to detect fire and smoke
Disaster aid and insurance
Education as mitigation stratergy
- In regions prone to wildlfires, education programmes, signs and posters are used to urge people to be careful and advise them on how to avoid starting fires by ; not leaving a fire or bbq unattended and extinguising it fully with soil and water, not discarding a lighted cigarette out a car window and removing litter particulary any broken glass
Managing vegetation as mititgation stratergy
- Clearing areas between trees and other vegetation ahead of wildfire events roe create fire breaks helps prevent the spread of the fire
- Backburning ahead of a wildfire - removing the fuel for the wildfire before the headfire reaches
- Natural firebreaks such as rivers ro control the sprad of the fire, or goals can remov ethe fuel prior to the wildfire event
- however, spotting where embers are carried far from the active fire can result in new fires being ignited elsewhere
Satellite and thermal imagery to detect fire and smokr
- Sattelites and infrared thermal vairation
- Cameras used to detect early igniton following lightning strikes
- NASA is developing drone technology for surveying vast areas such as the greast dismal swamp in the virgina north border of the usa
Disaster aid and insurance as mitigation stratergy
- E.g. diasier aid following 1983 ash wednesday
Other?
- Global early warning system for wildland fires (global ews) has also been developed to mitigate fire hazards - provides 1-2 day forecast using satelite technology to help those assessing the fire hazard in their decision making processess
- Wildfires insurance is often most expnesive form and can only be afforded by the wealthy and vulnerable communitues many of whom dont have insurance also dont prortect their homes in the vent of a wildfire hazard
Prevent
Stop the wildfire completley
Stratergies for prevention
Controlled burning
Public awareness
Lookout towers
Controlled burning as prevention stratergy
- Reduces the amount of fuel there is on the ground for wildlifres but there is always the danger that fire may get out of control
- Impact on the natural ecosystem and nutrient cycles by reducing the litter store
- Releases co2 into the atmosphere
- Must be undertaken in suitable weather conditions; only remove the litter not the trees
Public awareness as controlled stratergy
- Public awareness and community campaigns are often focused around the most vulnerable groups - especially in campsites and public areas where rules regarding the use of campfires and bbqs have to be strictly enforced
- Bottom Up approach
- Many countries operate fire bans during times of high risk
- Capigns fronted by character such as smokey bear can be effective - since 1994 urging americans to behave responsbiliy to fires 96% recognise him and 70% can recall his fire saftety maessage
- Avg number of ha lost fallen from 54m in 1994 to 16m today
- Tourist areas have notice boards at strategic locations carry warnings of fitr risk
- Individuals know to call emergency services on discovery of a wildlfire and the protect their proeprty by filling containers with water, turning on house lights to increase visibility in smoke and place a ladder against side of house before evacuations
- Fires are natural regnerative processes within forest ecosystems and should be allowed in certain circumstances to take their course
Smokey the bear
Lookout towers as prevention stratergy
- Fire lookout workers of the us forest service will live and work for weeks alone in the towers lookig for any hints of smoke in the sky
- Work long hours when fire season is at high risk of wildfires
- Any wildfires are called in and they despatch firefighter sin engines and helicopters
Why do people decide to adapt?
Many would argue that wf are natural process within forest ecosystems and they shouldnt be prevented from happening completley
For those who live in fire prone areas there is an acceptance that they will happen and that the best type of management is to adaptr
Wf are important as they burn away and old and diseased wood enbaling fresh growth as well as directly stimulating germination of certain species
Adapt
Accept the wildfire will happen and change what we do
Adaptation stratergies
Planning regulations and land use zoning
Building design
Restrictions on fires and bbqs in hazardoues areas
Planning regulations and land use zoning
- Used to reduce the hazard assocated with wildfires by restricting access to areas of risk during fire season
Building design
- An effective form of adaptation
- Buildings need to be relativley simple, cheap and made of natural producta that will not cause pollution if they get burned down, fire reistance materials, sprinklers, roll down metal doors and shutters
- Living with the possibility of fire damage is a risk taken by those who live in fireprone areas
Restrictions on fires and bbqs in hazardous areas
Signs in areas to prevent the people causing a wildfire through the use of fires of bbqs
Short term responses
- Spray fire with water and chemicals from the air and ground is costly
- Using sounwaves to douse the flames - soundwaves can manippulate both burning materila and oxygen that sorrounds it sound use to seperate the two - fire starved of oxygen and would put out the flames
- Firefighters on the ground to beat out flames and bulldoze vegetation to create firebreaks
- Retardant sprayed ontro building ahead of the fire
- Evacuation and emegency accomodation
- Deploy search and rescue teams
- Cost can run into millions of pound s
Retardant
A retardant is a substance added to materials to slow down or prevent the burning process, protecting them from ignition and fire damage
Long term responses
- Repair and rebuild infrasturcture
- Assess damage to vegetation
- Owners of land map damage and report to a central body which collates this information
- Reduce further risk from landslides and soil eorison in areas of steep topography by placing straw wattles (mats of straw) which intercept and absorb rainfa; and holf soil in place or replant trees
- replant trees to improve economy
- Set up community groups and prepare for next fire (parks response model)
