Water cycle in the Amazon

Question 1

Describe the Amazon rainforest

Answer 1

• 6 million km2
• mainly covers Brazil
• high amounts of precipitation, high humidity and high temperatures ranging from 22-34 degrees
• high cloud coverage

Question 2

What are the flows and stores in the water cycle

Answer 2

FLOWS:
- precipitation
- evapotranspiration 
- run-off
STORES:
- atmosphere 
- soil
- vegetation

Question 3

Describe the characteristics of precipitation in the Amazon

Answer 3

• High average rainfall = more than 2000mm
• High intensity convectional rainfall allows for high interception (about 10% of precipitation) - about 20-25% of evaporation

Question 4

Describe the characteristics of evapotranspiration in the Amazon

Answer 4

• High rates due to high temperatures, lots of moisture and vegetation
• Strong evapotranspiration-precipitation feedback loops
• 50% of incoming rainfall is returned by evapotranspiration
• Majority of evaporation occurs on leaves

Question 5

Describe the characteristics of run-off in the Amazon

Answer 5

• Rapid run-off is caused by intensive rainfall events and well-drained soils
• River discharge can peak in one or two months of the year

Question 6

Describe the characteristics of the atmosphere in the Amazon

Answer 6

• High temperatures allow atmosphere to store huge amounts of moisture
• Absolute humidity is high
• Relative humidity is high

Question 7

What is absolute humidity?

Answer 7

The mass of water vapour in a given volume of air

Question 8

What is relative humidity?

Answer 8

The mass of water in a given volume of air as a ratio of the mass needed to saturate it

Question 9

Describe the characteristics of the soil/groundwater in the Amazon

Answer 9

• Lots of rainfall and deep tropical soils leads to significant water storage in soils and aquifers

Question 10

Describe the characteristics of the vegetation in the Amazon

Answer 10

Rainforest trees absorb and store water and then release it through transpiration

Question 11

How are water losses replenished in the amazon?

Answer 11

By an inward flux of moisture from the Atlantic Ocean

Question 12

What physical factors affect flows and stores of water in Amazon

Answer 12

geology
relief
temperature

Question 13

Geology: How do impermeable catchments alter water cycle and give example

Answer 13

They have minimal water storage capacity which leads to rapid run-off
EG. Ancient Shield area of Amazon is made up of impermeable crystalline rocks

Question 14

Geology: Give an example of a permeable/porous rock in the Amazon

Answer 14

Limestone is a good storage of water and slows run-off

Question 15

Relief: What is the majority of the Amazon comprised of?

Answer 15

Extensive lowlands

Question 16

Relief: In areas with gentle relief how does water move?

Answer 16

Via overland flow (across the surface) 
Via throughflow (horizontally through the soil)

Question 17

Relief: What is the relief like in the West?

Answer 17

The Andes create steep catchments with rapid run-off

Question 18

Relief: What occurs annually across extensive floodplains? +eg

Answer 18

Widespread inundation

EG. The Pantanal

Question 19

Temperature: What do high temperatures cause in terms of weather?

Answer 19

High convection = high atmospheric humidity = thunderstorms = high precipitation

Question 20

Where is water cycled continuously, and by what flows?

Answer 20

Between the land surface, vegetation and atmosphere

By evaporation, transpiration and precipitation

Question 21

How much primary forest has been destroyed or degraded since 1970?

Answer 21

One third

Question 22

What is the average rate of deforestation in Amazonia between 1970 and 2013?

Answer 22

17,500km2 per year

Question 23

How has human activity modified stores and flows in water cycle + where?

Answer 23

In Upper Madeira drainage basin deforestation has:

• reduced water storage
• reduced precipitation rates as less evapotranspiration as fewer trees
• increased run off total and speed

Question 24

What happened in April 2014?

Answer 24

Floods on Madeira River (largest tributary of amazon)
Record levels of 19.68m above normal 
60 people died
68,000 families evacuated 
Outbreaks of cholera

Question 25

What was the main cause of Madeira River floods?

Answer 25

• Deforestation in Bolivia and Peru for subsistence farming and cattle ranching was the main cause
• Mainly occurred on steep lower slopes of Andes so massive reduction in water storage and accelerated run-off

Question 26

Converting rainforest to grassland increases run-off by how much?
How much rainfall goes straight into rivers from grassland?

Answer 26

A factor of 27

50%

Question 27

Why are rainforest trees crucial?

Answer 27

Rainforest trees are crucial in extracting moisture from soil, intercepting rainfall and releasing it into atmosphere by transpiration as well as stabilising forest albedo and ground temperatures - cycle sustains high atmospheric humidity which is responsible for cloud formation and heavy conventional rainfall so with deforestation the cycle can break and leads to permanent climate change

Question 28

How much is it predicted regional rainfall will decline by in the future?

Answer 28

20%

Question 29

Whats the main way of improving agriculture?

Answer 29

Diversification

Question 30

How can diversification be achieved?

Answer 30

• Rotational cropping

- Combining livestock with arable (would also allow a fivefold increase in production)