Water Scarcity (key terms)

Question 1

Blue water

Answer 1

Water that is stored in rivers, lakes, streams and groundwater (visible).

Question 2

Cryosphere

Answer 2

Describes the set of all locations on Earth where water is found in solid form, including areas of snow, sea ice, glaciers, permafrost, ice sheets and icebergs.

Question 3

Drainage basin

Answer 3

Area of land drained by a river and its tributaries. Separated by a watershed (area of highest land around it).

Question 4

Ecosystem functioning

Answer 4

The biological, chemical and physical processes that take place within an ecosystem.

Question 5

Ecosystem resilience

Answer 5

The capacity of an ecosystem recover from disturbance or withstand ongoing pressure.

Question 6

Flux

Answer 6

The flow or flowing of a liquid.

Question 7

Fossil water

Answer 7

Water contained in an undisturbed space (aquifer) for millennia or longer.

Question 8

Green water

Answer 8

Water stored in soil and vegetation (invisible)

Question 9

Saturated overland flow

Answer 9

Occurs when the soil becomes saturated, and any additional precipitation causes runoff.

Question 10

Water stress

Answer 10

If a country’s water consumption exceeds 10% of its renewable freshwater supply (or less than 1700m^3 per person per year)

Question 11

Physical water scarcity

Answer 11

When demand exceeds supply or when amount available falls to less than 1000m^3 per person per year.

Question 12

Economic water scarcity

Answer 12

When clean water is unaffordable even if its available or it is too expensive for people to access the water

Question 13

Absolute water scarcity

Answer 13

Renewable water supplies (from rivers, aquifers and lakes) become very low (less than 500m^3 per person per year). Leading to widespread restrictions.

Question 14

Water insecurity

Answer 14

When present and future water supplies cannot be guaranteed.

Question 15

Surplus

Answer 15

Precipitation is greater than potential evapo-transpiration and the soil water store is full so there is a surplus of soil moisture for plant use, runoff and recharging groundwater. Soil is at field capacity.

Question 16

Utilisation

Answer 16

Potential evapo-transpiration increases and exceeds precipitation, so there is more water evaporating from the ground surface and being transpired by plants than is falling as rain. Water is also drawn up from the soil by capillary action. The water is gradually used up.

Question 17

Deficit

Answer 17

The soil water has been used up by high rates of evapo-transpiration and low precipitation.

Question 18

Recharge

Answer 18

This occurs when potential evapo-transpiration decreases so that it is lower then precipitation and the soil starts to fill up again.

Question 19

Field capacity

Answer 19

The soil is now full of water and cannot hold anymore. Further rain could lead to surface runoff.

Question 20

Potential evapo-transpiration

Answer 20

The amount of evapo-transpiration that occurs as a result of temperature and vegetation as long as there is water available.