EQ2- CASE STUDY Flashcards
BRAZIL DROUGHT (2014-15): physical causes
in a normal year, where does the precipitation come from in the Amazon Basin
- moist air comes from the South Atlantic across the Amazon Basin
BRAZIL DROUGHT (2014-15): physical causes
what diverted the rain bearing winds during the 2014-2015 drought?
-a series of high-pressure systems diverted rain bearing winds further north, away from the Amazon, and also prevented them from diverting Southwards from the Andes.
- heavy rain then occurred in Bolivia and Paraguay, whilst dry air remained over Brazil
BRAZIL DROUGHT (2014-15): impact on people
what impact did this drought have on the people in Brazil
-water rationing for 4 million people, water supplies were cut off for 3 days in some towns
-the halting of HEP production which led to power cuts
-The depletion of Brazils 17 largest reservoirs to dangerously low levels- some down to just 1% of capacity
-increased groundwater abstraction, which led to aquifers becoming dangerously low
-a reduced crop of Arabica Coffee beans (Brazil is the worlds largest producer of these), which pushed up global prices by 50%
BRAZIL DROUGHT (2014-15): Human causes
In Sao Paulo state what did industries, domestic users and farmers increasingly have to use? why?
-they increasingly used groundwater as rivers ran low. Groundwater became the only water source for the urban and the poor and for remote rural areas
BRAZIL DROUGHT (2014-15): Human causes
Why were so many people digging illegal wells
to drill a single legal well, it costed $3500 to $100,000. This meant that many people avoided payment and instead drilled illegal wells
BRAZIL DROUGHT (2014-15): Human causes
Why did drilling illegal holes add to the problem of drought
The drilled illegal wells were not monitored for water safety. Drilling continued raising concerns about shrinking groundwater and illegal wells were less filtered so contained higher levels of industrial pollutants and bacteria
BRAZIL DROUGHT (2014-15): Impact on tropical rainforest ecosystems
Whats the flying river in the sky?
-Its the 400 billion trees in the Amazon rainforest that transport humidity inland from the Atlantic ocean.
-This flying river in the sky takes up 20 billion tonnes of water vapour daily and dumps it as rain on central and south brazil
BRAZIL DROUGHT (2014-15): Impact on tropical rainforest ecosystems
What are the chain reactions caused by drought that leads to forest stress?
-drought chain reaction= younger trees die which reduces canopy cover- this in turn reduces humidity, water vapour and thus rainfall. Exposed to tropical sunlight, dying vegetation and surface tree litter create a potential tinderbox that can catch fire. Lightning storms and high winds frequently turn a small fire into a wildfire. Long term drought means shorter trees and thinner canopies.
BRAZIL DROUGHT (2014-15): deforestation and feedback loops
scientists have suggested that the Amazon may have reached a tipping point, what do they mean by this.
-more frequent periods of drought are becoming clearer in the Amazon- its hydrological and climate cycle may have been changed permanently due to deforestation.
BRAZIL DROUGHT (2014-15): deforestation and feedback loops
How is the positive feedback loop of deforestation effecting the forest?
-the pos feedback loop of deforestation and less rainfall is reducing the ability for the forest to regenerate. As a result, rainforest ecosystems are less resilient and lower evapotranspiration and precipitation
BRAZIL DROUGHT (2014-15): deforestation and feedback loops
name 3 factors causing more extreme weather leading to more frequent drought
-positive feedback loop
-thinning of forests
-changing weather patterns (lower precip) link to high pressure systems
BRAZIL DROUGHT (2014-15): deforestation and feedback loops
what could future drought lead to?
- the capacity of the rainforest to absorb C will decrease
-more wildfires will increase level of C in atmosphere
-reduced rainfall will threaten Brazils dependence on HEP (this generates 70% of their electricity)
BRAZIL DROUGHT (2014-15): impact on wetland ecosystems
what happens in the Pantanal region during the seasonal rainfall floods
seasonal rainfall floods occur between November to April.
-Here, Pantanal changes from terrestrial to aquatic habitats. Flooding generally covers 80% of the Pantanal, even in dry years, the river is permanent.
BRAZIL DROUGHT (2014-15): impact on wetland ecosystems
why is the rainy season so important in the Pantanal region?
-its among the worlds most significant freshwater ecosystems. Its surrounded by areas with seasonal rainfall which means the aquatic and bird life there depends on permanent wetland for survival
BRAZIL DROUGHT (2014-15): impact on wetland ecosystems
what impacts did the 2014-15 drought have on the Pantanal region (wetland area)
-drought increased tree mortality which reduced habitats for wild animals as well as for cattle ranching for ecotourism
-wildfires became a major threat, caused by cattle ranchers deliberately setting old grass on fire to clear vegetation left un-grazed by their cattle (normal land management practice) however, during the drought, those fires spread out of control.
