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Geography 2022 > 5.4 > Flashcards

5.4 Flashcards

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1
Q

What are the short term causes of climate change?

A
  • Blocking anticyclones

- Reduced soil moisture

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2
Q

What are the mid-term causes of climate change?

A
  • ENSO cycles

- Hydrological stystem changes

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3
Q

Describe how Blocking Cyclones cause drought

A
  • The Polar frant jetstream moves northwards
  • This allows subtropical systems to move northwards
  • Creates stable hot calm weather with little rainfall
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4
Q

Describe how Reduced Soil Moisture causes drought

A

-Reduced precipitation causes soil to dry out stopping it from being a water source

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5
Q

Desricbe the effects of El nino

A

Warm water moves towards the west coast of South America, causing:

  • Warm waters off the coast of South America, increasing rainfall and the risk of flooding
  • Sinking air over Australia creates dry conditions which may turn into drought.
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6
Q

Describe the effects of La Nina

A

Warm water moves to the east coast of Australia, causing:

  • Reduced rainfall in South America
  • Increased evaporation in Australia causing more rainfall
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7
Q

Describe how cahnges in the Hydrological cycle cause drought

A

Reduced amount of precipitation causes less water to be in stores and transfers. For example rivers in mountainous areas have a lower discharge in summer due to reduced melt waters.

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8
Q

Describe how Global atmospheric circulation causes drought

A

Desending air between the Hadley and ferrel cells aswell as the polar cells causes hot and cold desert beanth. The areas located next to them are semi-arid and often expirence drought as well

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9
Q

Describe how Climate Change causes drought

A
  • Subtropical high pressure areas are getting stronger, which stops the seasonal movement of the ITCZ. (Which caused drought in Australia, 1997-2009)
  • Rainfall events have become more intensive rather than being spread over long periods of time.
  • Higher temperatures have change evaporation and wind patters which may cause rain baring winds to fail, causing reduced precipitation and drought
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10
Q

What human activities cause drought risk

A
  • Over abstabstraction of surface water
  • Over abstration of ground water
  • Deforestation
  • Climate change
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11
Q

Describe how over abstration of water sources creates drought

A
  • Taking too much water from lakes, rivers etc, causes reduced transfers and stores downstream
  • If precipitation is less than the water being taken out the drought conditions will worsen
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12
Q

Describe the impacts of deforestation on the hydrological cycle

A

Reduces interception, absorption and evapotranspiration so that water is lost from local areas. Increases vulnerability to drought

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13
Q

What are the imapcts of drought on wetlands

A
  • Make the ecosystem vulnerable
  • Reduces resillence to floods
  • Causes carbon to be released
  • Loss of habitat
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14
Q

How does drought reduce resillence to flooding?

A
  • Soil moisture is reduced
  • Drier soil is more susceptible to erosion
  • Less soil because of erosion causes the capacity to absorb flood waters to be reduced
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15
Q

How does drought cause carbon to be released?

A

-soil drys out and oxidises causing carbon to be released creating a positive loop, worsening the impacts of climate change.

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16
Q

How does drought impact on forests

A

Hydrolgial cyle will be disturbed if trees die or are damaged
Trees immune systems are affected causing them to susceptible to diseseas and pests
Trees dying causes a loss of habiat and food chains

17
Q

Name the 4 different types of drought

A
  • Food deficit
  • stream flow deficit
  • Rainfall deficit
  • Soil moisture deficit
18
Q

Impacts of rainfall deficit

A
  • Loss of soil moisture
  • Irrigation supply drops
  • Reduction in water available for consumption
19
Q

Impacts of Streamflow deficit

A
  • Reduced stores in lakes
  • Reduced water supply for urban populations
  • Poorer water quality
20
Q

Impacts of Soil moisture deficit

A
  • Poor yields from rain fed crops
  • Failing irrigation systems
  • livestock productivity fall
  • Rural industries affected
21
Q

Impacts of food deficit

A
  • Food shortages
  • Rural economy collapses
  • Rural to urban migration
  • Humanitarian crisis
22
Q

Do Human’s cause drought?

A

Human factors don’t cause drought, However they do act like a positive feedback loop

23
Q

What are the human causes of drought in the Sahel?

A
  • Increase in the number of animals being farmed

- Population growth

24
Q

Describe the positive feedback loop of increased live stock numbers in causing drought in the Sahel

A
  • There was a 40% increase in the number of livestock
  • Land was over grazed
  • soil depleted in nutrients and was stripped of it’s protective grass cover
  • Leads to Soil erosion and deforestation

Geography 2022 (18 decks)

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