Miss McDonald EQ2 (ON SPEC) Flashcards

1
Q

Meteorological drought

A

Degree dryness compared ‘normal’ precipitation

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2
Q

Agricultural drought

A

Insufficient water for crops so that they wilt without irrigation

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3
Q

Hydrological drought

A

Where drainage basins suffer shortfalls

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4
Q

Global atmospheric circulation

A

-low pressure=warm air rises+cools forming precipitation
-high pressure=cool air falls+warms surface bringing clear skies no rainfall
E.g. ‘sub tropical’ band 30degrees N/S air risen equator cooled+sinks forming belt high pressure hot,dry conditions

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5
Q

ITCZ

A
  • Belt low pressure(rain) migrates W/seasons 23degrees N/S or 0- alternating wet+dry seasons
  • may fail blocked high pressure from descending part Hadley(high pressure) or loops jet streams occasionally break up allowing high pressure from subtropics move N+ block bringing droughts mid latitudes (UK)
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6
Q

ENSO

A

El Niño+ La Niña(opposite) shift rainfall patterns

  • El Nino brings warmer water to America’s reducing rainfall W pacific
  • la Nina brings warmer water to extreme W of tropical pacific reducing rainfall W americas
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7
Q

Flooding UK-jet stream+ low pressure weather

A

As Mid latitudes=boundary zones polar+tropical air masses where jet steam formed-brings low pressure(frontal rain)by meeting warm+ cold air+uplift condensation
Sometimes high pressure blocks jet stream+ continually delivers low pressure to 1area high pressure either side

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8
Q

Flooding India-monsoon

A

Intense seasonal rainfall-widespread damaging flooding
Around 70%annual avg rain 100days July-Sept, 80%Bangladeshi ppl affected, 1/2 country less 12m above sea lvl, low-lying plains largest rivers most at risk along river courses+at edge delta

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9
Q

Flooding Siberia-Ice melt

A
  • Siberian snow melt spring causes extensive flooding across interiors Asia e.g. River Ob
  • Quick transition winter-spring upstream causes rapid snow melting while lower reaches remain frozen W/v limited infiltration
  • Flood water often held up temp ice dams
  • Sometimes rain falls melting snow when rapid thaw occurs-> this combo can cause heavy flooding
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10
Q

Physical primary meteorological causes Cumbria floods 2015

A
  • flooding happened 3rd time 2015 in a decade 2005,2009+2nd wettest nov since 1910
  • moist air mass stayed over Cumbria up to 48hrs delivering records amount rain
  • jet stream remained over N longer usual normally moves N+S brought low pressure (rain) from across Atlantic thru ‘conveyor’ warm+v moist air from Caribbean where sea temps unusually high
  • Cumbria= wettest seathwaite avg 2mrainfall/yr
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11
Q

Secondary causes for Cumbria floods 2015

A
  • steep slopes Cumbria Mountains helped steer run rapidly into river (orographic rainfall)
  • ground already saturated from previous antecedent conditions meant additional rain flowed surface run-off straight into rivers
  • rivers Derwent+Cocker= already swollen W/ previous rainfall
  • impermeable rock type Lake District impeded infiltration
  • Cockermouth built confluence 2rivers making susceptible flooding after heavy rains
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12
Q

Soc impacts Cumbria floods 2015

A
  • 3000homes flooded 2005+5,200 2015
  • 40skls closed
  • routine business across NHS hospitals cancelled
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13
Q

Econ impacts Cumbria floods

A
  • UK dented as much £3bn damage storms Eva, Desmond+ Frank
  • insurance claims caused flooding 2015 exceeded £6bn
  • house prices fell flood-risk areas
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14
Q

Environ impacts Cumbria floods

A
  • river chocked W/debris+contaminated sewage+ effluents+ pollutants
  • saturated ground-decomposition dead plants+animals giving off noxious gases- contaminated food chains+threatened wild life
  • soils=eroded habitats destroyed+ecosystems destroyed
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15
Q

How climate change might affect drainage basin if drier than normal

A
  • Decreases precipitation 10-30degrees N+S equator(inputs)
  • initial high rates evaporation followed lower lvls when available water falls+EVT decrease as less soil moisture affecting veg as outputs
  • reduce lvl water stored soil, rivers+lakes causing increased reliance+use groundwater W/more humidity+ increased drought severity+freq
  • Increasing high pressure zones e.g. subtropics+ drier soils altho more intense rainfall events
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16
Q

How CC might affect drainage basin if wetter than normal

A
  • inputs increase->Increase soil moisture more stored rivers+lakes W/no reliance+ less use groundwater, cause more evaporation+ convection increasing risk flooding as more saturated ground more surface run off
  • 1degree rise temp-could increase global runoff 40%
  • Overall decreased snow, permafrost+ice cover as stores initially increased meltwater increasing river floods but decreasing long-term
17
Q

Impacts CC Sahel

A
  • possible change climate since 1996 7wet yrs in between droughts + opportunities re-greening
  • planting trees+ bushes along other schemes so regeneration water retaining veg low cost, water harvesting tech also stone lines built Burkina Faso retain moisture (traps)
  • if works increase inputs naturally+evaporation+EVT from veg- more storage rivers,lakes+ soil W/more runoff+stream flow
  • but rainfall extremely variable 100-600mm/yr+ rains might fail W/CC if tropics warm up, ITCZ won’t migrate as far N+ ‘summer’ rains will fail so uncertainty
18
Q

Impacts CC California

A
  • fall precipitation+rise temp-increase evaporation rates, surface runoff+ soil moisture lvls decrease forested areas reverted scrub+grassland
  • relying groundwater fallen 30m 2011-15
  • reservoir lvls fallen Oct 2016 water storage 77%avg time of yr
  • permanent snow lvls 2015=record low due high temps+ lack winter storms crucial coz meltwater=1/3water used Cali cities+farms
  • forecast suggest 50%chance mega droughts hitting SW Cali +90% decade long drought
  • worsening situation BUT uncertainty if mitigation (help/schemes) not as dry
19
Q

Uncertainty of future CC projections

A
  • complexity of climate systems
  • natural short-term oscillations e.g. ENSO brings insecurity +sunspot cycles
  • bio geochemical positive+feedback systems
  • incomplete set date (not collected all locations+as detailed)
  • no clear evidence flooding getting bigger+more frequent
  • many other factors increase pop riskier locations, land used changes, rising pop, poor farming+normal variability
  • don’t know where+ how much
20
Q

Concerns over water security

A
  • every 1degrees temp rise amount moisture held atmosphere increase 7% potential heavier precipitation W/2010 wettest yr
  • change precipitation, temp+ potential ET severity+occurrence droughts rise
  • more intense droughts affects more ppl Australia+ spreading new areas S EU, SW USA+ Sahel
21
Q

Intense storms cause floods

A

Severe storms e.g. tropical cyclones Bring lots rainfall short time moving quickly into channels unable soak into ground causing overflow
In arid+semi occasional thunder drop lots rain suddenly runs quickly over baked ground- ‘flash’ flood

22
Q

Heavy rainfall causing floods

A

Lots rain short time perhaps caused cold front in low pressure system- too much allow through flow/ groundwater flow take place so excess water quickly runs off surface +into river channels where discharge increase to flood lvls

23
Q

Prolonged rainfall causing flooding

A

Persistent rain long period perhaps result 7 low pressure systems passing over area- sequence frontal rainfall
First soil saturated so later rainfall can’t infiltrate
Runoff increased+ quickly enters river channels causing floods

24
Q

Other factors about Sahel

A

25%drop agricultural production since 2010, rise 20-60% food prices past 5yrs, 15.6m ppl affected Sahel

25
Q

Human causes Sahel drought (CS) 2012/13 animals

A

Increase animals some areas livestock 40% pluvial yrs(water) before mid 1960s-overgrazing soil depleted nutrients, land stripped protective grass cover so veg can’t re-est-desertification

26
Q

Human causes Sahel drought (CS) 2012/13 pop

A
  • pop growth from more immigrants (refugees civil wars+droughts) increasing demand wood cooking+heating+building especially urban areas-deforestation (mainly fuel wood)-veg removed increasing erosion+evaporation-desertification
  • pop growth high birth rates+ lowering death rates w/annual growth rates 2.5-4% farmers forces change trad land use->more needed food+ cash crops- over cultivation: reduced soil fertility, soil left exposed rain+ wind- desertification
27
Q

Impacts of droughts wetlands (Florida) explain

A
  • wetlands=not resilient drought owning reliance submergence water prolonged time
  • drough major impact limited prec, less interception as veg deteriorate+less infiltration+ percolation groundwater stores- water table fall
  • process evaporation continue+ might increase from less-protected surface while transpiration rates decrease-wetland less functional+ desiccation can also accelerate destruction wild fires
28
Q

Impacts of droughts on wetlands (Florida) services environ

A
  • supporting ecosystem-primary production energy net rated 1,000gC/m^2/yr (1/2 rainforest which= most), nutrient recycling, food webs, carbon store!
  • regulate water- flood control absorb excess water (+storm surges) prec release slowly back protecting shorelines+ plant species anchor soil w/roots, groundwater recharge areas, purifies water plant species absorb excess nitrogen+ other pollutants
29
Q

Impacts of droughts on wetlands (Florida) services human

A
  • providing- fuelwood+peat, fish mammals+ birds
  • aesthetic beauty from plant species
  • recreation (hunting, bird watching fishing) cultural value
  • econ value breeding grounds many aquatic animals provide us w/food +7 food plant species= dependent on wetlands
30
Q

Impacts of droughts on forests (Cali) natural function human+environ

A
  • gds timber food etc
  • soc+cultural benefits recreation, spirituality
  • carbon storage calc avg 0.73tonnes/hectare/yr(important regulating CC)
  • nutrient cycling, water+air purification+maintenance habitat species, soil preservation
31
Q

Impacts of droughts on forests (Cali) resilience

A
  • not resilient drought some species tree lower resilience+drought stressed tree-foliage loss impairing growth
  • increasing accumulation pests+diseases+ damage vascular tissues impairing water transport
32
Q

Impacts of droughts (Cali) recent yrs

A

-droughts getting worse recent yrs destruction+size W/CC all but 1/10 biggest forest fires past 2 decades, drier warmer conditions-veg dying out+more flammable+ drying out soils lowering water table reduces natural protection (CC) + winter seasons rain/snow shorter

33
Q

Human factors increase flood risk (freq+mag) pop

A
  • pop growth-> land use changes+ urbanisation
  • urbanisation rural urban migration creation impermeable surfaces increases surface runoff 60%residents ldn paved front garden
  • dams reduce discharge downstream, drains/sewers reduce lag time, impending flow building alongside W/bridges narrow channels high water lvls downstream+ levees
  • deforestation woodlands lost=intercept rain+transpire moisture+roots-gd soil structure
34
Q

Human factors increase flood risk (freq+mag) management

A

-poor river management-straightening channels(realignment)increase flow+ risk+ resectioning by dredging widening+deepening increase capacity faster movement+channelisation removes marshy areas

35
Q

Human factors increased flood risk (freq+mag) agriculture

A
  • Land use changes (increased pop) w/agricultural development-> deforestation, overgrazing, ploughing/ drowning wetlands usually occuring upstream knock on effect down stream
  • increased run-off +lvls sediment can block river channels downstream, grazing animals trample soil+ ploughing compacts-> increased run-off+ sprinkling groundwater onto arable crops
36
Q

Human factors increased flood risk (freq+mag) pol

A

-econ+pol budget cuts flood defences, green priorities EU Water Framework Directive puts environ concerns before regular maintenance+ advocates making space flood lowlands, poor land management blocking+econ growth building flood plains+ modifying landscapes