Droughts

Question 1

Since when has there been a drought in the Sahel?

Answer 1

1960’s

Question 2

What are the three physical reasons for the drought in the Sahel?

Answer 2

Tropical convection.
The West African Monsoon.
El Niño.

Question 3

How has tropical convection caused a drought in the Sahel?

Answer 3

The huge towering thunderstorms that build quickly in tropical areas

Question 4

How has the West African Monsoon caused a drought in the Sahel?

Answer 4

Rains which starts to spread across the Sahel in June with the arrival of the ITCZ.

Question 5

How has El Niño caused a drought in the Sahel?

Answer 5

The effects of the warming of the Pacific, which also affects the weather around the globe.

Question 6

In the 1970’s what was widely believed to have caused the drought in the Sahel?

Answer 6

Farmers in the regions, blaming them for the degradation of the land and the desertification.

Question 7

What is currently the most convincing theory about the drought in the Sahel?

Answer 7

Due to the change of temperature of the surrounding oceans. At the new of the 1900’s, the South Atlantic and the Indian Oceans warmed quickly, which reduced the difference in temperature between the land and the sea. This may have caused monsoon to weaken and the thunderstorms to remain to the south.

Question 8

Why is it difficult to predict the future of the drought in the Sahel?

Answer 8

Scant availability of historical data from across the region.

Question 9

What human activities contributed to the 14-15 drought in Brazil?

Answer 9

Over abstraction of surface-water resources and groundwater aquifers, as water companies tried to maintain the water supply for factories and services, and residents tried to avoid cuts in supply.

Question 10

Which part of Brazil was the most affected by the 14-15 drought and why?

Answer 10

South east. In Sao Paulo state, industries, domestic users and farming increasingly used groundwater as rivers ran low. Groundwater became only water source for the urban poor and for remote rural areas.

Question 11

What were the problems regarding fees in Brazil during the 2014-2015 flood?

Answer 11

High fees of $3000 for a license to drill a well. Cost of drilling was also high itself. Meant that people drilled illegal wells, which were not monitored for water safety.

Question 12

Hydrologists believe that what percentage of wells were illegal during the 2014-2015 drought in Brazil in Sao Paulo?

Answer 12

70%

Question 13

What were the problems with illegal wells in Sao Paulo during the 2014-2015 drought?

Answer 13

Illegal wells are generally shallower and less filtered by bedrock, so they contain industrial pollutants and higher levels of bacteria.

Question 14

Why is the Amazon rainforest referred to at ‘Earth’s lungs’?

Answer 14

Absorbs CO2 and returns oxygen to the atmosphere.

Question 15

How many billion trees are located in the Amazon rainforest?

Answer 15

400 billion

Question 16

How many tonnes of water is carried by the Amazon River back to the Atlantic Ocean everyday?

Answer 16

17 million

Question 17

What is the chain reaction affecting the Amazon rainforrest in case of a drought?

Answer 17

Prolonged drought causes forest stress, and sets up a series of chain reactions. Younger trees die, which reduces the canopy cover- this, in turn, reduces humidity, water vapour and therefore rainfall. Exposed to tropical sunlight, dying vegetation and surface tree litter create a potential tinderbox that can easily catch fire. Lightning storms and high winds frequently turn a small fire into a wildfire. Long-term drought means shorter trees and thinner canopies.

Question 18

What were the two major effects on The Pantanal during the 2014-15 drought, testing its resilience and long term survival?

Answer 18

The drought increased tree mortality, which in turn reduced habitats for wild animals- as well as for cattle ranching and ecotourism.
Wildfires became a major threat, caused by cattle ranchers deliberatly setting old grass on fire during the dry season to clear vegetation left ungrzed by their cattle. However, during the drought, those deliberate fires easily spread out of control into the wetlands and forests.

Question 19

How is rainfall in Brazil normally predictable?

Answer 19

Moist air moves in a westerly direction from the South Atlantic across the Amazon Basin.
When the moist air encounters the high Andes mountain range to the west of the continent, it is forced to turn southwards - maintaining the flow of moisture around the Basin.

Question 20

Physically, what has happened during the 2014-15 Brazil drought?

Answer 20

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 rains then occurred in Bolivia and Paraguay, whilst dry air remained over Brazil.

Question 21

2014-15 drought Brazil: There was water rationing for how many people?

Answer 21

4 million

Question 22

What led to power cuts in Brazil during the 2014-15 drought?

Answer 22

Halting of HEP production.

Question 23

How many of Brazil’s reservoirs were depleted to dangerous levels during the 2014-15 drought?

Answer 23

17

Question 24

In Brazil, what led to aquifers to become dangerously low?

Answer 24

Increased groundwater abstraction

Question 25

By how much did global coffee prices increase by and why during Brazil’s 2014-15 drought?

Answer 25

50%

A reduced crop of Arabica coffee beans.