The Hydrologic Cycle

Question 1

List the three states of water.

Answer 1

Solid (ice, temperatures 100ºC)
Liquid
Vapour (temperatures >100ºC)

Question 2

How much of the land’s surface do oceans cover?

Answer 2

70%

Question 3

How much water is held in the oceans?

Answer 3

93 to 97%

Question 3

What do oceans contain?

Answer 3

High concentrations of mineral salts.

Question 4

How much water is held as fresh water?

Answer 4

3%

Question 5

How much water is held as ice?

Answer 5

75% of fresh water

Question 6

How much water is held as groundwater?

Answer 6

25% of fresh water

Question 7

How much of our weight (human weight) is water?

Answer 7

70 to 90%

Question 8

What does water drive?

Answer 8

The biogeochemical cycles.

Question 9

Why is water important to the Ecosphere?

Answer 9

Gives the planet its characteristic colour
Sculpts the planet’s surface
Crucial role in supporting life – transfers oxygen, nutrients and waste products
Medium for chemical reactions
Water movement defines climates and weather patterns
Maintains biomes and ocean regulate temperature

Question 10

How much water enters the atmosphere from the oceans?

Answer 10

419,000 km³

Question 11

How does water moderate temperature?

Answer 11

Oceans convert insolation to heat.
It is distributed through ocean currents.
Coastal waters regulate coastal temperatures while extremes of temperature are confined to inland locations.

Question 12

What powers the water cycle?

Answer 12

Solar energy

Question 13

How are water molecules evaporated?

Answer 13

Solar energy heats the surface water, molecules absorb heat (latent heat) converting them to vapour

Question 13

What processes do solar energy control?

Answer 13

Evaporation
Condensation
Precipitation

Question 14

How does transpiration assist plants?

Answer 14

Allows water to be pumped up to the foliage bringing nutrients Cools leaf surfaces.

Question 14

Describe the process of condensation.

Answer 14

Vapour expands in uplift and cool air.
Less able to hold water vapour.
Converts to cloud droplets around condensation nuclei.
Can freeze to form ice crystals.

Question 15

What is the size of a cloud droplet?

Answer 15

1 (0.001mm) to 100 microns

Question 18

List the 4 types of precipitation.

Answer 18

Rain
Hail
Sleet
Snow

Question 19

How much evaporation becomes effective precipitation?

Answer 19

25%

Question 20

List the 9 factors affecting precipitation.

Answer 20

Latitude
Climate zone
Ocean surface temperatures
Major ocean and air currents
Season
Temperature
Prevailing winds
Air pressure zones 
Topography

Question 21

Where does most rain fall?

Answer 21

In the equatorial regions, coastal and high mountain ranges.

Question 22

Describe the importance of precipitation to groundwater supplies.

Answer 22

Water which is not intercepted can infiltrate the soil and rock structure to add to aquifers.

Question 23

List the 6 factors influencing infiltration.

Answer 23

Amount of vegetation cover (interception)
Depth of humus
Openness of canopy
Leaf form and size
Structure
Complexity of vegetation

Question 24

Why is humus important to soil water content?

Answer 24

Intercepts water, reduces runoff, holds absorbed water on the surface.

Question 25

List the 4 processes controlling water once it is on the Earth’s surface.

Answer 25

Topography Vegetation type Soil characteristics Condition of the humus layer.

Question 33

How does runoff (overland flow) affect the soil?

Answer 33

Moves soil contributing to erosion

Question 34

How does vegetation affect infiltration?

Answer 34

Increases interception, increasing infiltration

Question 35

What is porosity?

Answer 35

Degree of openness of soil and rock particles

Question 36

How is water held in the soil?

Answer 36

Fills spaces between the particles

Question 37

What is an aquiclude and how does it affect groundwater?

Answer 37

An impervious layer which prevents water movement

Question 38

Where is the water table highest and deepest?

Answer 38

Under hills

Question 39

Name some discharge or collection points.

Answer 39

Natural wells; sub-artesian and artesian bores (hydrostatic pressure) and springs. Collection occurs where porous soils and strata lie on the surface.

Question 40

When do water tables rise and fall?

Answer 40

Under seasonal conditions – rise in the wet season and fall in the dry season

Question 41

List the 4 types of springs.

Answer 41

Seepage Fracture Tubular Mineral

Question 42

Describe the characteristics of Australia’s Great Artesian Basin.

Answer 42

It is 1.7 million km2 which is 22% of the continent. It has layers of sandstone, siltstone and mudstone. It is 3km thick with a 10.3 quadrillion litre capacity.

Question 43

How can limestone be impermeable, yet contain spectacular underground features caused by water.

Answer 43

Lime stone has very small particles and low porosity so is impermeable. It is also soft (CaCO₃) and can easily be absorbed by water.

Question 44

How important is groundwater to Australians?

Answer 44

Underlies 60% of Australia; 5.25 million km2; 70% is suitable for domestic use and irrigation

Question 45

What is ‘hard’ and ‘soft’ groundwater?

Answer 45

Hard water is mineralised with calcium, potassium, sodium and magnesium.