Freshwater Change and the Hydrologic Cycle (module 3)

Question 1

Give the % of Earth’s water that is freshwater and the % of freshwater that is easily accessible for human use

Answer 1

• 3% of Earth’s surface water is freshwater
• 0.009% of Earth’s surface water is usable and available

Question 2

Explain where most accessible water comes from globally, and where Vancouver’s water supply comes from

Answer 2

Vancouver - Capilano, Seymour, Coquitlam watershed
Globally - surface water sources such as rivers, lakes, and reservoirs, snow and land ice, glaciers, ice sheets, ice caps, ponds, streams

Question 3

Label the natural hydrologic cycle with respect to the stores/pools of Earth’s water and the main processes/fluxes that move water through the cycle

Answer 3

Stores- oceans, ice and snow, groundwater, surface water, lakes, atmosphere
Main fluxes - evaporation, transpiration, sublimation, condensation, precipitation, infiltration, runoff, surface flow

Question 4

Give at least 2 examples of ways in which human actions can alter the natural hydrologic cycle

Answer 4

• Urbanization (less infiltration, increased surface runoff)
• Dams ( altered flow dynamics)
• Deforestation (less infiltration)
• Accelerating ice discharge

Question 5

Identify and give an example of the three causes of major regional trends in freshwater storage

Answer 5

• Climate Change ex. changes in precipitation patterns, temperature, and evaporation can impact freshwater storage in a region
• Human activities ex. dam construction impacts downstream water availability
• Land use changes ex. urbanization, reduces infiltration

Question 6

Distinguish between “blue water” and “green water” and explain why the freshwater planetary boundary was updated in 2022 to include green water

Answer 6

Blue water - Freshwater available for human use (rivers, lakes, reservoirs)
Green water - Freshwater available for ecological functions (terrestrial precipitation, evaporation, and soil moisture)
- approach to water resource management that considers the connections of terrestrial ecosystems, land use practices, and freshwater availability

Question 7

Identify the control variables and planetary boundaries for global freshwater use as suggested in 2015 and for green water as suggested in 2022

Answer 7

2015 - Global (max amount of consumption freshwater) - 4000 km3/yr
- Basin (freshwater withdrawal as % of mean monthly river flow) - low flow (25%), intermediate (30%), high-flow (55%)
- 2600 km3/yr
2022 - root-zone soil moisture (<10% of ice-free land area on which root-zone soil moisture is wetter or drier than normal variability in any month of the year)
- 18%

Question 8

List the steps of the scientific method

Answer 8

• observation
• question
• hypothesis
• experiment
• control/experimental setup
• analysis
• conclusion

Question 9

Where is Groundwater stored

Answer 9

Aquifers
- only accessible by drilling or pumping from wells