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? (Sphere)

Answer 3

Hydrosphere, lithosphere, cryosphere, atmosphere

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

Question 29

What is latent heat?

Answer 29

The sun heats water - breaking bonds, but not 100%. Water molecules take in energy from surrounding to 100% break bonds

Question 30

What is condensation?

Answer 30

Vapour to liquid. Opposite to latent heat, which is released as the molecules join

Question 31

Why is evaporation seen as a cooling process?

Answer 31

It takes in heat from the surroundings

Question 32

Of the global water stores, where is water stored most?

Answer 32

96.5% oceans 1% other saline waters 2.5% freshwater

Question 33

Of the 2.5% global freshwater stores, where is water stored most?

Answer 33

70% glaciers 30% groundwater 1.2% surface/other freshwater

Question 34

Of the 1.2% surface waters in the 2.5% freshwaters, where is most water stored?

Answer 34

69% permafrost/ground ice 21% lakes 4% soils 3% atmosphere 0.5% rivers

Question 35

What is a the water balance?

Answer 35

The difference between the inputs and outputs (and subsequent changes in storage)

Question 36

What is a positive water balance?

Answer 36

If precipitation exceeds runoff and evapotranspiration as the water stored will increase

Question 37

What is the soil moisture budget?

Answer 37

Closely linked to the water balance. The change in the amount of water stored in the soil throughout the year

Question 38

What are the main factors involved in the soil moisture budget?

Answer 38

Evapotranspiration potential (linked to temps) and precipitation

Question 39

What is the runoff?

Answer 39

Amount of water in a river

Question 40

What is given by measuring river discharge?

Answer 40

Level of runoff at a given time

Question 41

For the water balance, what is the calculation to find the precipitation?

Answer 41

Precipitation = runoff + evapotranspiration +/- change in storage

Question 42

What is the calculation to find the river discharge (cumecs)?

Answer 42

Discharge = Cross section x water speed

Question 43

What are the controls on the level of river discharge?

Answer 43

Volume of water, speed/velocity