14. Human impact on the water cycle Flashcards
How much % of earth’s surface is covered by water?
70%
What is condensation?
A change from a gas to liquid as a result of a temperature drop.
How much percent of water is used for agriculture, industry, and domestic use?
- Agriculture: 70%
- Industry: 22%
- Domestic use: 8%
Which industries use a lot of water? Name 3.
- Power generation
- Coal-fire
- Nuclear power plants
- Textile industry
- Paper and pulp
- Food and bevarage
- Chemical
Why is irrigation inefficient? Name 3 reasons.
- Over-irrigation
- Water-intensive crops
- Monoculture
- Lack of recycling
What is blue water?
Freshwater found in rivers, lakes, reservoirs, groundwater aquifers.
What is green water?
Portion of rainwater absorbed by soil and used by plants through evapotranspiration (does not runoff).
What is grey water?
Wastewater from domestic activities (used blue water) such as washing machines, doing laundry, bathing.
What is black water?
Wastewater from toilets (used blue or treated grey water) that contains faecal matter and urine.
How is grey water managed?
- 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
How is black water managed?
Black water requires intensive treatment and the release into blue water; filtering; chemicals; etc. to remove pathogens etc.
Define water footprint.
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).
Define blue water footprint and provide an example
- 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)
Define green water footprint and provide an example
- Volume of rainwater absorbed by soil and consumed by plants through evapotranspiration during the production of a products
- Example: agricultural purposes (natural irrigation)
Define grey water footprint
- 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)
Define black water footprint
There is no black water footprint because by definition it is included in the blue water footprint.
How can green and blue water fooprints be indirectly affected by climate change?
- 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
Name 2 example functions and roles of green water
- Sustaining natural ecosystems
- Securing land carbon sinks
- Maintaining regional climates
- Supporting plant growth
What was the critique of the original water Planetary Boundary?
Only includes blue water
Apart from the six-subboundaries, what was the other suggested solution for an updated Water Planetary Boundary?
Distinguish between blue and green water.
What was the conclusion of the ecological status by the EU Water Framework DIrective?
60% of water bodies are in moderate/poor/bad ecological condition
Which product was “responsible” for the depletion of the Aral Sea?
Cotton
Name 2 solutions that could have prevented the depletion of the Aral Sea.
- Eficient irrigation techniques
- Usage of mulch
- Conscious consumer choices
- Organic cotton
- Hemp
Name 2 solution to avoid unequal water access and consumption in Cape Town.
- Income adjusted pricing
- Community engagement
- Connection between levels of government
