14. Human impact on the water cycle

Question 1

How much % of earth’s surface is covered by water?

Answer 1

70%

Question 2

What is condensation?

Answer 2

A change from a gas to liquid as a result of a temperature drop.

Question 3

How much percent of water is used for agriculture, industry, and domestic use?

Answer 3

• Agriculture: 70%
• Industry: 22%
• Domestic use: 8%

Question 4

Which industries use a lot of water? Name 3.

Answer 4

• Power generation
• Coal-fire
• Nuclear power plants
• Textile industry
• Paper and pulp
• Food and bevarage
• Chemical

Question 5

Why is irrigation inefficient? Name 3 reasons.

Answer 5

1. Over-irrigation
2. Water-intensive crops
3. Monoculture
4. Lack of recycling

Question 6

What is blue water?

Answer 6

Freshwater found in rivers, lakes, reservoirs, groundwater aquifers.

Question 7

What is green water?

Answer 7

Portion of rainwater absorbed by soil and used by plants through evapotranspiration (does not runoff).

Question 8

What is grey water?

Answer 8

Wastewater from domestic activities (used blue water) such as washing machines, doing laundry, bathing.

Question 9

What is black water?

Answer 9

Wastewater from toilets (used blue or treated grey water) that contains faecal matter and urine.

Question 10

How is grey water managed?

Answer 10

• Grey water is diluted with blue water to turn into blue water
• Grey water is treated and then recycled for e.g. toilet flushing or irrigation which reduces blue water needed

Question 11

How is black water managed?

Answer 11

Black water requires intensive treatment and the release into blue water; filtering; chemicals; etc. to remove pathogens etc.

Question 12

Define water footprint.

Answer 12

The water we remove from the natural water cycle for a period of time (altering the physical state) and the amount of water we pollute (altering the chemical state).

Question 13

Define blue water footprint and provide an example

Answer 13

• Volume of freshwater found in rivers, lakes, reservoirs, groundwater aquifers consumed or polluted during the production of a product or service
• Examples: domestic purposes (e.g. drinking water), agricultural purposes (e.g. irrigation), industrial processes (e.g. cooling)

Question 14

Define green water footprint and provide an example

Answer 14

• Volume of rainwater absorbed by soil and consumed by plants through evapotranspiration during the production of a products
• Example: agricultural purposes (natural irrigation)

Question 15

Define grey water footprint

Answer 15

• Volume of freshwater (blue water) required to dilute pollutants in grey wastewater
• Only refers to management of grey water that includes dilution with freshwater before discharging into water bodies to ensure certain water quality)

Question 16

Define black water footprint

Answer 16

There is no black water footprint because by definition it is included in the blue water footprint.

Question 17

How can green and blue water fooprints be indirectly affected by climate change?

Answer 17

• Increased temp > more ET > dryer conditions > drought
• Increased temp > increased saturation vapor pressure > increased air humidity > when temp drops, heavy rain and snowstorms
• Due to these shifts, timing intensity and frequency of weather events have been altered

Question 18

Name 2 example functions and roles of green water

Answer 18

• Sustaining natural ecosystems
• Securing land carbon sinks
• Maintaining regional climates
• Supporting plant growth

Question 19

What was the critique of the original water Planetary Boundary?

Answer 19

Only includes blue water

Question 20

Apart from the six-subboundaries, what was the other suggested solution for an updated Water Planetary Boundary?

Answer 20

Distinguish between blue and green water.

Question 21

What was the conclusion of the ecological status by the EU Water Framework DIrective?

Answer 21

60% of water bodies are in moderate/poor/bad ecological condition

Question 22

Which product was “responsible” for the depletion of the Aral Sea?

Answer 22

Cotton

Question 23

Name 2 solutions that could have prevented the depletion of the Aral Sea.

Answer 23

• Eficient irrigation techniques
• Usage of mulch
• Conscious consumer choices
• Organic cotton
• Hemp

Question 24

Name 2 solution to avoid unequal water access and consumption in Cape Town.

Answer 24

• Income adjusted pricing
• Community engagement
• Connection between levels of government

Question 25

Name 2 barriers of introducing solutions to Cape Town’s unequal water access and consumption situation.

Answer 25

• Political factors
• Data and monitoring gaps
• Behavioural factors