3.1.1.2 The Water Cycle

Question 1

What are the five main sub-systems?

Answer 1

Lithosphere
Hydrosphere
Cryosphere
Atmosphere
Biosphere

Question 2

What percentage of global water is stored in oceans?

Answer 2

96.6%

Question 3

How much of the Earth’s water is fresh water?

Answer 3

3.7%

Question 4

Of the total amount of fresh water on Earth, what percentage is stored as snow and ice?

Answer 4

69%

Question 5

Of the total amount of fresh water on Earth, what percentage is groundwater?

Answer 5

30%

Question 6

Of all fresh water on earth, how much is surface or atmospheric water?

Answer 6

1.2%

Question 7

What are the five main oceanic stores?

Answer 7

Atlantic, Pacific, Indian, Arctic and Souther

Question 8

What are the five main stores of cryospheric water?

Answer 8

Sea Ice - Antarctica
Ice Caps - Icelandic cap
Ice sheets - Greenland
Alpine Glaciers - Mer de Glace , France
Permafrost - Alaska

Question 9

How much would sea levels rise by if the Greenland ice sheet melted?

Answer 9

6m

Question 10

If the Antarctic ice sheet melted, how much would sea levels rise?

Answer 10

60m

Question 11

What are the main stores of terrestrial water?

Answer 11

Surface
Ground
Soil
Biological/biomass

Question 12

What are the main processes in the water cycle?

Answer 12

Evaporation, condensation, transpiration, cloud formation, precipitation formation

Question 13

What are the main processes in the cryosphere?

Answer 13

Accumulation - snow building up

Ablation - melting

Question 14

How long does water typical remain in rivers?

Answer 14

2-6 months

Question 15

How long does water typical remain in soil?

Answer 15

1-2 months

Question 16

How long does water typical remain in ground water?

Answer 16

100-100,000 years

Question 17

How were water stores different to 18,000 years ago - last ice age?

Answer 17

Thicker/Larger ice sheets and glaciers
Higher extent of permafrost
There would be much less liquid water so oceans would be about 100m lower
Atmospheric water levels would reduce as low temps don’t encourage evaporation
Low temperatures limit plant growth, so smaller stores in the biosphere

Question 18

Outline global precipitation

Answer 18

precipitation is high around the equator/between the tropics in the low pressure zones
high at mid latitudes

Question 19

what is low pressure?

Answer 19

rising warm air, moist air cools and condenses to form huge clouds and heavy rain

Question 20

where is precipitation very low?

Answer 20

at around 30 degrees N and S

Question 21

Why is precipitation high at mid latitudes?

Answer 21

due to the convergence of warm air from the tropics and cold air from the Arctic creates an active polar front.
Moist tropical air from the south is forced to rise over denser cooler air from the north resulting condensation, cloud formation and rain

Question 22

what are the main processes in the drainage basin

Answer 22

precipitation, evapotranspiration, surface run off, infiltration, throughflow, stemflow, percolation, ground water flow

Question 23

what are the main stores in a drainage basin?

Answer 23

from shortest to longest : interception, soil moisture, river channel, surface storage, ground water

Question 24

what happens to the stores in a drainage basin during winter?

Answer 24

temperatures are lower so there is less plant growth
evapotranspiration is lower infiltration and soil storage will increase until saturation is reached
increase in run off and the risk of flooding

Question 25

what happens to the stores in a drainage basin during summer?

Answer 25

higher temperatures mean greater evapotranspiration so less water is stored on the surface or is available for infiltration greater vegetation cover increases infiltration and transpiration so less water reaches ground water stores. river levels are likely to fall

Question 26

what is river discharge and how is it calculated?

Answer 26

the volume of water passing a given point in a given time expressed in cumecs channel cross section area x velocity

Question 27

what is a river's regime?

Answer 27

the typical rises and falls in river discharge over the course of a year

Question 28

for a typical river in the UK, when would river discharge occur during a year and why?

Answer 28

the winter months have greater precipitation than evapotranspiration so soil water stores fill up

Question 29

for a typical river in the UK, when would soil moisture utilisation occur during a year and why?

Answer 29

spring months as temperatures rise and evapotranspiration exceeds precipitation and the water store is used by plants

Question 30

or a typical river in the UK, when would a soil moisture deficit occur during a year and why?

Answer 30

summer months as all soil moisture is used up and any precipitation will now go into the soil rather than a river so river levels fall

Question 31

or a typical river in the UK, when would soil moisture surplus occur during a year and why?

Answer 31

end of winter/early spring as precipitation is greater than evapotranspiration and the soil has already been recharged so their is a surplus flooding can occur when the soil is saturated

Question 32

what is a storm hydrograph and why are they important?

Answer 32

a graph of the discharge of a river following a rainstorm event they are important because they can predict how a river might respond to a rainstorm which can help in river and flood management

Question 33

what terms label a storm hydrograph?

Answer 33

rising limb, falling limb, peak discharge, lag time, baseflow, peak rainfall

Question 34

what physical factors could lead to a river having a short lag time?

Answer 34

``` small, circular drainage basin steep relief of slopes antecedent rainfall impermeable soil or rock limited vegetation intense or prolonged rainfall ```

Question 35

what human factors could lead to a river having a short lag time?

Answer 35

deforestation, farming practices, urbanisation

Question 36

what are some effects of a long period of drought on the water cycle?

Answer 36

initially high rates of evapotranspiration until surface stores dry up vegetation destroyed by wildfire which removes all processes trees are accountable for groundwater transfer will continue to feed rivers until the water table drops too far causing some rivers to dry up

Question 37

what are some effects of a severe storm on the water cycle?

Answer 37

intense rainfall will exceed infiltration capacity of the soil leading to flash flooding limited amounts of water will reach groundwater stores

Question 38

why will land use change of urbanisation and deforestation cause change in the water cycle?

Answer 38

catchment areas that are no longer natural are less likely to have permeable surfaces for precipitation to infiltrate to. increased risk of flooding and flash flooding soil erosion will occur at a quicker rate due to the removal of trees

Question 39

why will agricultural change cause change in the water cycle?

Answer 39

some farming practices result in excess drainage of the ground livestock can compress soil which reduces soil storage capacity soil is left vulnerable to erosion after ploughing and harvesting of crops

Question 40

why will water abstraction cause change in the water cycle?

Answer 40

if water is removed faster from aquifers than it is replenished, then the water table will fall and ground stores will reduce over time. this can lead to falling river levels and the intrusion of salt water from the sea in areas near to the coast