The Water cycle - Global scale

Question 1

How is global water storage distributed?

Answer 1

97% oceans
2.5% freshwater stores (69% glacier, 30% groundwater)
0.5% other saline water

Question 2

How is global freshwater storage distributed?

Answer 2

69% glaciers, 30% groundwater, 0.03% rivers and streams

Question 3

Where can water be stored?

Answer 3

Hydrosphere, lithosphere, cryosphere, atmophile

Question 4

What is the hydrosphere?

Answer 4

Any liquid water (oceans, lakes, rivers, etc)

Question 5

What is the lithosphere?

Answer 5

Water stored in the crust and upper mantle

Question 6

What is the cryosphere?

Answer 6

Any water that is frozen (glaciers, permafrost)

Question 7

What is the atmosphere water store?

Answer 7

Water vapour

Question 8

What are aquifers?

Answer 8

Underground water stores. Unevenly distributed

Question 9

How long can shallow groundwater aquifers store water?

Answer 9

up to 200 years

Question 10

How long can deeper fossil aquifers store water?

Answer 10

Formed during wetter climatic periods. May last for 10,000 years

Question 11

How long do glaciers store water for?

Answer 11

From accumulation to ablation, 20-100 years. May feed lakes that store water for 50-100 years

Question 12

How long does seasonal snow cover and rivers store water for?

Answer 12

2-6 months

Question 13

How long does soil store water?

Answer 13

Temporary store. 1-2 months

Question 14

What does ITCZ stand for?

Answer 14

The inter-tropical convergence zone

Question 15

What is the global atmospheric circulation model?

Answer 15

The main factor that determines cloud formation and rainfall

Question 16

What causes the ITCZ?

Answer 16

Different zones of rising and falling air leading to convectional rainfall. This creates a low pressure zone on the equator called the ITCZ, which has very heavy rainfall

Question 17

Why does the ITCZ move?

Answer 17

It moves during the seasons (north and south) as the sun positions change. The ITCZ is where the two hadley cells meet

Question 18

What are the NATURAL processes which change the water cycle? (5)

Answer 18

Seasonal changes, storm events, drought, la nina/el nino, cryospheric processes

Question 19

How do seasonal changes impact the global water cycle?

Answer 19

Summer: Less precipitation - more evapotranspiration (because of higher temps)
Winter: Reduced flows in water cycle as water stored in ice. Reduced interception

Question 20

How do storm events influence the global water cycle?

Answer 20

Sudden increases in rainfall - flooding and replenishment of some water stores

Question 21

How do droughts impact the global water cycle?

Answer 21

Cause major stores to be depleted and the activity of flows acting within the water cycle to decrease. More common as a result of global warming

Question 22

How do el Nino and la Nina impact the global water cycle?

Answer 22

El Nino: every 2-7 years. Causes warmer temperatures
La Nina: every 2-7 years. Causes cooler temperatures.
Climate change likely to increase probability of El Nino

Question 23

How do cryospheric processes impact the global water cycle?

Answer 23

Almost all of the world’s glaciers are shrinking, causing sea levels to rise.
If all ice caps melt, sea levels would rise 60 metres

Question 24

What are the human impacts that change the global water cycle? (3)

Answer 24

Farming practices, land use change, water abstraction

Question 25

How do farming practices impact the global water cycle?

Answer 25

Ploughing breaks up the surface - Increased infiltration
Arable farming - Increase interception and evapotranspiration
Pastoral farming - compacts soil - reduced infiltration and increase runoff
Irrigation - removes water from local rivers, decreasing their flow

Question 26

How does land use change impact the global water cycle?

Answer 26

Deforestation (e.g. for farming) - reduces interception, evapotranspiration but infiltration increases.
Construction reduces infiltration and evapotranspiration, increase runoff

Question 27

What is water abstraction?

Answer 27

Water removed from stores for human use

Question 28

How does water abstraction impact the global water cycle?

Answer 28

Reduces volume of water in surface stores.
Abstraction increases in dry seasons
Abstraction from aquifers usually greater than inputs - global decline in long term water stores