W&C - The Water Cycle: Global Scale

Question 1

What are the percentages of stores of water globally?

Answer 1

97% oceans
3% freshwater - 69% ice caps and glaciers, 30% groundwater, 1% surface/freshwater

Question 2

What are the four main stores of water globally?

Answer 2

Hydrosphere, atmosphere, lithosphere, cryosphere

Question 3

What is the hydrosphere?

Answer 3

All liquid water

Question 4

What is the lithosphere?

Answer 4

All water stored in the crust and upper mantle

Question 5

What is the atmosphere?

Answer 5

Water vapour

Question 6

What is the cryosphere?

Answer 6

All water stored as ice

Question 7

What are aquifers?

Answer 7

Underground stores of water, and are unevenly distributed

Question 8

Draw the earth with the 3 cells and global atmospheric circulation

Answer 8

In my notes!!!

Question 9

Describe The Intertropical Convergence Zone (ITCZ)

Answer 9

• Solar radiation hits the equator directly
• causes warm air at the equator to rise and spread towards the ferrel cells
• the area where warm air is rising has low pressure, and condenses when it rises
• leads to cloud formation and encourages rainfall
• (high pressure prevents cloud formation and therefore rainfall)
• since the earth is on a 23 degree axil tilt, as it orbits the sun, the ITCZ moves between the tropic of cancer and the tropic of capricorn
• results in the formation of seasons - some countries experiences a dry climate while others a very wet one
• Example = India lies near the tropic of cancer, so in the July, when the ITCZ reaches the toc, there are high amounts of rainfall in the summer (also why there are a lot of monsoon in India)

Question 10

What are the physical changes to the global water cycle over time?

Answer 10

Cryospheric processes
- accumulation and ablation, which result in rising and falling sea levels
- ablation decreases cryospheric stores globally
- increasing with climate change
- if all of the ice caps and glaciers around the world melted, sea levels would rise by 60m

Storm events
- sudden increases in rainfall can lead to flooding - increases hydrospheric stores
- also replenished lithospheric stores (not long term)

Droughts
- depletes major stores of water and can be a long term problem as they become more common with climate change

Question 11

What are the human factors changing the the global water cycle over time?

Answer 11

Water abstraction
- being increasingly use as population and demand increases
- extraction > replenishment, so the stores are rapidly declining
- reduces volume of water in surface stores

Changing land use
- deforestation
- urbanisation

Farming practices
- pastoral farming = compacts the soil as livestock tramples on it, which reduces infiltration
- arable farming = plants provide interception and also increase evapotranspiration

Question 12

Define discharge

Answer 12

The volume of water flowing in a cross sectional point of a river, at any given time

Question 13

What is discharge measured in?

Answer 13

Cubic metres (cumecs)

Question 14

Define rising and falling limb

Answer 14

Rising = increasing river discharge
Falling = decreasing river discharge

Question 15

What is baseflow?

Answer 15

The volume of groundwater flow

Question 16

What is stormflow?

Answer 16

Throughflow + surface runoff

Question 17

What is bankfull discharge?

Answer 17

Maximum capacity of the river channel - there will be flooding if the river discharge exceeds this

Question 18

Components of a flashy hydrograph:

Answer 18

• short lag time
• steep rising and falling limb
• higher peak discharge
• higher flood risk

Question 19

Components of a subdued hydrograph:

Answer 19

• more gradual rising and falling limb
• lower flood risk
• lower peak discharge
• longer lag time

Question 20

Name and explain the physical factors affecting the flood hydrograph

Answer 20

Antecedent rainfall
- rainfall before the studied event can mean that the soil is already saturated, so there will be very high surface runoff

High intensity rainfall
- increases river discharge
- soil gets saturated much more quickly, which increases surface runoff

Type of drainage basin
- small or circular basin = rainfall reaches the river more quickly

Question 21

Name the human factors affecting the flood hydrograph

Answer 21

• urbanisation
• deforestation
• farming practices

Question 22

give an example of the impact of water abstraction on the water cycle

Answer 22

• regions have experience groundwater levels declining by up to a metre per year, which is alarming because they are not being replenished at the same or faster rate