The Concepts Of System And Mass Balance

Question 1

What is the scale of stores in the global water cycle?

Answer 1

Oceans - 97%
Icecaps - 2%
Groundwater - 1%
Rivers & lakes - 0.01%
Soil moisture - 0.01%
Atmospheric moisture - 0.01%

Question 2

How does the water cycle impact humans?

Answer 2

Humans - Rely on water to live
Settlements - Where we build settlements
Food chain - Lack of water affects animals affects food chain

Question 3

Why are groundwater reserves important?

Answer 3

Source of 33% of water within households and business
Drinking water for 90% of rural population
42% of irrigation water is from groundwater
2005, 23% of freshwater in US came from groundwater
Requires work to access but can supply water needs of people, unlike surface water

Question 4

How does urbanisation affect groundwater?

Answer 4

Waste water can be used for irrigation or recharge aquifers.
Solid waste disposal pollutes groundwater.
Urban growth means housing built in areas used for solid waste disposal
E.g. Merida, Mexico, obtains 240 million litres per day from limestone aquifer. No sewage system, aquifer is now contaminated

Question 5

How does agriculture affect groundwater?

Answer 5

Reduced long term viability of irrigated agriculture
E.g. High Plains of Texas, pre 1930s, groundwater system was stable. Used at rapid rate to supply irrigation schemes. In under 50 years, water level declined by 30-50mm in Lubbock, Texas. Aquifer narrowed by +50%

Question 6

How does industry affect groundwater?

Answer 6

Worst polluters tend to be smaller enterprises, e.g. paper, textiles etc.
Acids, oils, fuels discharged directly into groundwater
E.g. London, due to 46% deduction in groundwater abstraction water table in tertiary beds has risen by 20m. Rise results in increase in spring and river flows, surface water flooding and pollution of surface water