Water Cycle Case Study - Drought in South America

Question 1

What is the usual rainfall in 2014-2015?

Answer 1

Usual rainfall versus 2014-2015
* Usually, moist air from the South Atlantic encounters the Andes mountain range. This forces its
southward, creating a flow of moisture around the basin.
* In 2014-2015, high pressure systems diverted moist air further North, causing heavy rains in
Bolivia and Paraguay but dry air over Brazil.

Question 2

What are the impacts of the droughts?

Answer 2

• Water rationing for 4 million people.
• Brazil relies heavily on HEP for its power, so the drought caused power cuts.
• Increased groundwater abstraction.
  o In Brazil, there are high fees to drill wells. This has led to a vast number of illegal wells.
  Infact, 70% of wells are illegal. Illegal wells are shallower and polluted.
• The Arabica Coffee bean crop reduced, which drove global coffee prices up 50%.
• By 2015, main reservoirs had reached 5% of their capacity.
  Impacts of drought in the Amazon

Question 3

What are the impacts of drought in the Amazon?

Answer 3

Rainforests recycle ½ of their rainfall, so deforestation could trigger a positive feedback loop
causing further drought.
* A drying forest means reduced soil water storage and evapotranspiration. It also means that
uncontrolled wildfires are much more likely to occur.
* Prolonged drought causes forest stress, which could lead the Amazon to a tipping point ( a
sudden change from which it could never return).
* The Amazon intakes 20 billion tonnes of water vapour, which is mostly released over Brazil as
rain.

Question 4

What are the worldwide impacts?

Answer 4

• Loss of a carbon sink.
• Wildfires.
• Changes to ENSO.

Question 5

What is the value of The Pantanal – South America (Brazil and Upper Paraguay)

Answer 5

The Pantanal – South America (Brazil and Upper Paraguay)
Value
* The Pantanal is a significant freshwater ecosystem for birds and aquatic wildlife.
* The river floodplain is vital and relies on seasonal rainfall.
* When the seasonal rainfalls come, 80% of the Pantanal is flooded. The wetlands retain
60% all year round.

Question 6

What are the impacts of the 2014/2015 drought?

Answer 6

• The drought tested the resilience of the ecosystem.
• There was an increase of tree mortality, which reduced habitats.
• There have also been more wildfires, due to routine grass burning by cattle farmers
  igniting the dry forest.