Flashcards
wildfires
Flashcards do conjunto (27)
- 1what is a wildfire?- term used for uncontrolled fire fuelled by natural vegetation
- in Australia = bush fires
- North America = brush fires
- often start in rural, wilderness areas but migrate to rural-urban fringes, affecting buildings, animals+people - 2what are the 3 types of wildfire?- ground fire: where ground itself (peat, tree roots) burns, slow, smouldering fire with no flame+little smoke
- surface fire: where leaf litter+low-lying vegetation burn, can be low or high intensity
- crown fire: where fire moves rapidly through canopy, likely to be intense+fast-moving - 3for a natural fire to occur, what 2 things are needed?- an ignition source: lightening = main cause, climate will affect frequency of electrical storms, particularly one where there's hardly any rainfall, increasingly as a result of humans, e.g. falling power lines, discarded cigarettes, camp+agricultural fires
- fuel: has to be of sufficient quantity+dry enough to burn, climate affects frequency+duration of droughts, type of vegetation that will grow in an area+rate @ which litter is produced - 4how does the vegetation type affect the intensity?- thick undergrowth or closely spaced trees allow fire to travel easily
- some trees like eucalyptus+pine contain a lot of oil+so burn easily
- eucalyptus trees shed strips of bark which help it spread quickly - 5fuel characteristics?- fine, dry material (e.g. long grass, thin twigs) catch fire+burn most easily
- large amounts of fuel that form continuous cover will help fire burn for longer+spread - 6climate+recent weather?- rainfall must be sufficient enough for vegetation to grow, so plenty of fuel
- area usually has distinct dry season where rainfall = low for significant time, warm+dry weather causes water in vegetation to dry up > more flammable
- strong winds provide more oxygen to help fire burn+spread burning embers - 7fire behaviour?- fire burns in different ways, e.g. creeping fire moves across ground surface fairly slowly, running fire spreads rapidly+is more intense
- can throw out burning debris (firebrands) that help it spread+become more intense - 8where are wildfires likely to occur?- areas with combination of dry vegetation+lightening strikes
- areas with dry season, e.g. semi-arid climate+susceptible to drought
- mediterranean climate regions+savannah grasslands
e.g. parts of Australia
e.g. US+Canada: Cali+Alberta
e.g. Southern Europe: Italy, Greece - 9can fires aid new seed germination?yes
- they clear vegetation
- stimulate growth of certain plants+rid area of some insects+parasitezs - 10what is pyrophytic vegetation?- pyrophytes = plants adapted to tolerate fire
- through mechanisms like resistant bark, e.g. baobab tree - 11what is a good example where wildfires are a continuing problem?- LA Basin in California
- much of area covered by drought resistant chaparral, after summer drought can be tinder dry
- dry wind: Santa Ana increases dryness to point where an ignition could easily cause a major fire
- large area of low density housing+large amounts of vegetation exposed - 12what are the physical factors that affect the extent of impacts?- frequency/regularity of fires
- magnitude
- length
- amount of fuel
- wind
- hot,dry weather - 13what are the human factors that affect the extent of impacts?- community preparedness
- risk management (b4, during+after)
- level of education
- past experience
- occupation/employment
- vulnerability
- population density - 14what are the social effects?- loss of life: most are away from people but some move so fast ppl can be trapped, e.g. Victoria 173 deaths
- loss of property: due to urban expansion more communities @ risk, e.g. Sydney+LA, can cause homelessness
- toxic gases+particulates: Southeast Asia 'haze' = large scale air pollution > respiratory problems - 15what are the economic impacts?- loss of crops+livestock: have huge impact in timber producing areas, may take years to replace trees
- in USA estimates $10 million spent fighting fires a day - 16environmental?- loss of wildlife: Indonesia fires of 1997 destroyed Wein River orangutan sanctuary on Kalimantan
- increased flood risk: rain comes in heavy bursts + loss of so much vegetation + so interception > flooding
- damage to soil structure+nutrient content: intense heat generated @ ground level > destroy nutrients+alteration in soil structure - 17political?- evacuation: many flee+not allowed back into affected area so emergency shelters/accommodation will have to be provided with food, etc
- 18explain 'managing the vegetation'- controlled burning to get rid of little
- creating firebreaks in vegetation in advance rather than during - 19explain 'managing the built environment'- increased gap between houses+vegetation
- incorporating more fire resistant methods in construction, e.g. stone+brick rather than wood, spark arresters to chimneys - 20explain 'modelling'- studying ways in which fires behaviour with computer stimulations to comprehend+predict fire behaviour
- 21explain education- make people aware regarding home safety+how to avoid starting fires
- 22explain warning systems- put in place by establishing lookout towers+air patrols
- tourist areas notice boards @ strategic locations - 23explain being well insured- wealthier countries people urged to take out insurance against fire damage
- can be very expensive in fire prone areas - 24how can the event be dealt with as it happens?- fighting fires as they happen
- very dangerous
- spraying with water+chemicals from ground+air
- work on ground beating out flames+bulldozing large breaks in vegetation preventing fires jumping certain directions
- retardants to slow pace of wildlife sprayed on fires which are inaccessible or where human safety+structures endangered - 25explain replanting trees 1- particularly in commercial forestry areas to improve economy of areas devastated by fires
- 26explain replanting trees 2- after vegetation removed by fire + great danger of flooding+mudslides on unprotected slopes
- planting trees will stabilise slopes - 27explain preparedness- making sure people are better prepared for next fire by having emergency supplies ready, survival kits
- setting up community groups, e.g. Victoria
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- GCSE Geography (hazards) FlashCards sobre wildfires, criado por serena norman thomas em 21-05-2018.
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- serena norman thomas
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