Chapter 4.1 Flashcards
What is meant by the Earth’s water budget?
A quantitative estimate of the distribution and movement of water within the hydrological cycle.
What percentage of the Earth’s water is freshwater?
Only about 2.5–3% of Earth’s water is freshwater.
Where is most of the Earth’s freshwater stored?
69% in glaciers and ice sheets, 30% as groundwater.
What percentage of Earth’s total water is stored in the atmosphere?
Only about 0.001%.
Define the term ‘turnover time’ and list it for oceans, ice caps, groundwater, rivers, and the atmosphere.
Turnover time is the average time a water molecule spends in a store. Oceans: 37,000 yrs; Ice caps: 16,000 yrs; Groundwater: 300 yrs; Rivers: 12–20 days; Atmosphere: 9 days.
How can water be both a renewable and a non-renewable resource?
It’s renewable if replenished naturally (e.g., rivers), non-renewable if in slow-recharging sources (e.g., aquifers, ice caps).
What are the main components (stores and flows) of the hydrological cycle?
Stores (e.g., oceans, glaciers) and flows (e.g., evaporation, precipitation, runoff).
What are the driving forces behind the movement of water in the hydrological cycle?
Solar radiation and gravity.
Name five major water stores in the hydrological cycle.
Oceans, lakes, groundwater, glaciers and ice caps, atmosphere.
What is the difference between a transfer and a transformation in the water cycle?
Transfers involve water movement in the same state; transformations involve a change of state.
Give three examples of transfers in the water cycle.
Surface runoff, infiltration, streamflow.
Give three examples of transformations in the water cycle.
Evaporation, condensation, freezing.
Define the terms: infiltration, percolation, and surface runoff.
Infiltration: water enters soil; Percolation: water moves through rocks; Runoff: water flows over land.
Explain the processes of evaporation, condensation, and transpiration.
Evaporation: liquid to gas; Condensation: gas to liquid; Transpiration: water loss through plants.
Why is the global water cycle considered a closed system?
Because no water enters or leaves the Earth, only energy flows in/out.
How does a local water system differ from the global system?
Local systems are open with matter and energy entering/leaving.
What is meant by maximum sustainable yield in water systems?
The highest rate water can be used without reducing future availability.
How do seasonal variations affect water inputs and outputs?
They influence precipitation, runoff, and evaporation.
List three human activities that withdraw water from natural systems.
Domestic use, agriculture, industry.
What are some common pollutants humans discharge into water?
Fertilizers, sewage, chemicals.
How does urbanisation affect water flow and availability?
It increases runoff, reduces infiltration, and raises flood risk.
What is canalisation and how does it affect water systems?
It’s the straightening of rivers in concrete channels; speeds flow, reduces storage.
How do dams and dykes impact water systems?
They alter flow, create reservoirs, and affect ecosystems.
What effects does diverting rivers have on the environment?
It can reduce flow downstream and change habitats.
