physical geography - wildfires

what is a wildfire?

what is a wildfire?

a fire which is burning out of control in the open

what is needed for a fire to start?

heat and light - combustion

how do wildfires spread?

a fire spreads when it has enough heat to keep it burning into unburnt areas - a transfer of energy

how does fire spread with a small fuel load?

fire spreads gradually, with low power

how does fire spread with lots of fuel?

fire spreads quickly

how does a fire spread with dry fuel?

fire burns quicker and is harder to maintain

how do wildfires spread so quickly?

as the fire advances, it dries out the material just past it’s warmth and smoke moving towards potential fuel makes the fire’s dampness vanish

→ makes the fuel simpler to light when the fire arrives

what is the climates role in wildfires?

• dry spells create good conditions for wildfires and strong winds can make the wildfire move quickly and set alight more land

  → temperature, wind and humidity

how does temperature influence wildfires?

→ influences the starting of wildfires

when the wood, trees and bushes on the ground get warmth from the sun which dries potential fuel

how does wind influence wildfires?

supplies the fires with extra oxygen, further dries potential fuel and pushes fire over the land at a quicker rate - the stronger the breeze, the quicker the fire spreads, the fire can toss its coals and embers in the air which can create new fires - spotting

wind can also alter the course of the fire and blasts can raise the fire into the trees, creating a crown fire

how does humidity influence wildfires?

neutralises the fire, can bring down the odds of wildfires starting and precipitation can smother any potential wildfires from breaking out

how does mountainous terrain effect fire spread?

• fires generally travel uphill quicker than downhill - the more extreme the slope, the quicker the fire ventures

• fire can preheat the fuel further up the slope because the the smoke and warmth are ascending towards that path

what are some social primary impacts of wildfires?

• deaths and injuries

• displacement of people

• damage to properties and infrastructure causing disruption to people’s lives

• damage/destruction of crops

what are some social secondary impacts of wildfires?

• mental health issues

• health issues such as respitory illness

• homelessness

• food shortages

what are some economic primary impacts of wildfires?

• destruction of property and infrastructure

• disruption of trade and economic activity

• loss of income and employment

• costs of immediate responses

what are some economic secondary impacts of wildfires?

• slower economic growth and development

• increased economic inequality as impacts are more severe for vulnerable people

• increased costs of insurance and hazard management strategies

what are some environmental primary impacts?

• loss of biodiversity

• atmospheric pollution from smoke/toxic gases

• water pollution as ash gets into water

what are some environmental secondary impacts?

• increased soil erosion due to lack of trees and vegetation

• lack of soil fertility

what are some of the short-term responses to wildfires?

• firefighters try to contain and extinguish the fire as soon as possible

• warnings and evacuation notices issued

• water sprayed onto land

• fire diverted away from settlements

what are some of the long-term responses to wildfires?

• public education campaigns

• using less flammable materials in construction

• preparing and training emergency services

• creating fire breaks in forested areas

what are some preparation and adaptation responses to wildfires?

• satellites and infrared sensors can be used to improve early detection and monitoring - Thermal infrared satellite imagery shows where wildfires are occurring so that people can stay away from these areas.

• warnings can be issued to allow time for evacuation - Broadcasted weather warnings (or ‘Red Flag Warnings’ as they are commonly referred to as) warn people when the perfect conditions for wildfires are occurring - e.g. hot, dry, upcoming lightning storms. This means people may wish to evacuate and campfire bans can be put in place.

• evacuation plans prepared and emergency services trained to improve responses

• education campaigns can inform people how to create defensible spaces around their homes

• public awareness can prevent the ignition of wildfires and prepare people for wildfires. e.g. Smokey Bear is a 70 year-old U.S. mascot used to provide information on preventing wildfires, with the intention of becoming a well-known figure so that people would recognise the risks.

what are some mitigation and prevention strategies for wildfires?

• firefighters use helicopters to drop water and fire retardants onto fires to reduce the intensity of the fire and slow its speed

• backburning is a strategy where the firefighters light small fires ahead of a wildfire to reduce the amount of fuel available + fire breaks

• public awareness schemes

• monitoring weather for wildfire conditions

• land use zoning can be used to reduce the amount of flammable material and building codes can be implemented to ensure fire-resistant materials are used in construction and sprinkler systems are installed.

• search and rescue teams, immediate aid, and evacuations

• firefighters spray water onto the fire. Water and flame retardants are also sprayed onto large areas using aircrafts.

what is the wildfires case study?

black summer bushfires, australia - began september 2019 and ended march 2020

what were the causes of the wildfire?

• 2019 was australia’s driest and hottest year on record

• much of australia’s forest is made up of eucalyptus which are flammable

• loss of traditional fire management strategies used by aboriginal people increased vulnerability

what were the primary impacts of the bushfires?

→ social:

• 33 people were killed directly

• 80,000 people were displaced

→ economic:

• destruction of farms, crops and livestock estimated to cost around $5 billion

• cost of firefighting estimated at over $2 billion

→ environmental:

• destroyed habitats and ecosystems, killed an estimated 3 million animals

• 400 million tonnes of CO2 released which led to hazardous air quality in sydney

• Over 3,000 homes and thousands of other buildings were destroyed.

• Critical infrastructure, including roads, bridges, and power lines, was severely damaged.

• Smoke from the fires caused hazardous air quality levels in major cities, including Sydney, Canberra, and Melbourne.

• The smoke plume spread globally, affecting countries as far as South America.

what were the secondary impacts of the bushfires?

→ social:

• almost 450 people died from smoke inhalation

• Prolonged exposure to smoke resulted in increased respiratory and cardiovascular problems among the population.

• Mental health issues surged due to trauma, loss of property, and displacement.

→ economic:

• slow down in economic activity due to disruption to trade and industry reduced GDP growth

• lost for for reconstruction of homes and infrastructure

• The economic cost of the fires was estimated at over AUD 100 billion, considering damages, firefighting costs, and economic losses.

• Agriculture and tourism sectors were particularly hard hit, with long-term effects on local economies

→ environmental:

• increased soil erosion and lack of soil fertility

• release of carbon emissions contributes to climate change

• the fires released a significant amount of carbon dioxide into the atmosphere, exacerbating climate change.

• Recovery and regrowth of vegetation will take years, affecting carbon sequestration.

• Ash and debris runoff contaminated water supplies, affecting both human consumption and aquatic ecosystems.

• The fires disrupted water catchment areas, impacting water availability and quality.

what were the short-term responses to the bushfires?

• around 80,000 firefighters tackled the fires

• temporary accomodation was set up in sports centres and community halls

• the government payed a disaster recovery payment of $1,000 per adult affected

• fundraising campaigns raised money for the response e.g. animal rescue and WWF raised almost $200 million for animal rescue and rehabilitation

what were the long-term responses to the bushfires?

• government gave over $2 billion to bushfire recovery and provided financial assistance to affected communities and business

• provision of mental health services for affected people

• development of a range of mitigation strategies e.g the creation of the national bushfire recovery agency to co-ordiante relief efforts and support re-building

• environmental restoration through initiatives such as the creation of a koala hospital and breeding programme

• early warning systems developed

what vegetation type leads to wildfires?

Thick, close together vegetation allows fires to spread quickly and easily. T

rees and thick bushes lead to more intense wildfires; grasslands do not burn as intensely. Vegetation with flammable oils - like eucalyptus - causes more intense fires also.

what fuel characteristics do wildfires need?

Vegetation should be dry to allow it to catch. Finer vegetation causes fires to spread quicker, but larger, thicker forms of vegetation burns for longer and more intensely.

what are crown fires?

Crown fires burn the entire tree from bottom to top , which is classed as the most dangerous and destructive type of fire.

what are surface fires?

burn the leaf litter, meaning they are easy to extinguish.

what are ground fires?

burn at the dry peat or vegetation beneath the surface , and move slowly through the dried underground.

Due to them being underground, they can be difficult to put out and can actually continue to burn throughout the year if the weather conditions allow it.