3.6 Water

Question 1

Describe methods of water supply and the proportions of water used for agriculture, domestic and industrial purposes in countries at different levels of economic development

Answer 1

LEDC: directly from rivers, lakes, ponds
MEDC: storage systems (dams/reservoirs), desalination, water recycling

Climate:
rain-fed- uses less water
irrigated farming: more water used

Development

rich: higher consumption
poor: lower consumption

Industrialisation
factories use a lot of water

Question 2

explain why there are water shortages in some areas and demonstrate that careful management is required to ensure future supplies

Answer 2

Reasons for water shortages:

• Limited supply: not enough rivers/lakes
• Drought: prolonged period of reduced rainfall
• Global warming: hotter-more droughts
• Pop growth: higher demand (+people= +water)
• Overconsumption: rich use more water
• Irrigation (more people = more farming in dry areas)
• Conflicts (going to get water is risky)

Management:

• Conservation: low flush toilets, low use machines, different plants
• Recycling: re-cleaning water
• Increasing supply: more reservoirs, drill holes
• Improve cleanliness
• Water pricing: charge more = people use less
• Desalination: there’s plenty of sea water

Impact of lack of access to clean water:

• Water borne diseases: cholera, diarrhoea
• Long/dangerous journey to collect (mainly young girls in danger and miss school to travel long distance for water)
• Food supply: can’t grow crops
• Cleaning/sanitation impacts: won’t use water for cleaning if you dont have a lot of it
• Less industries: factories need water supply

Question 3

case study

Water supply in a country or area

Answer 3

California

Key facts:

• 80% of water for farming
• 60% of rain in N Carolina, but 60% of people in S Carolina
• Drought conditions for 3 years

Places:
- San Joachim and Sacramento rivers + delta
Sierra Nevada mountains
- Hetch Tetchy reservoir
- Owens valley reservoir and pumping station
- Los Angeles
- Central valley

Where water comes from:

• Rainfall /mainly snow) in the Sierra Nevada mountains in the N of state
• Snow melt into the main rivers in spring
• Natural store from 2 main rivers in the San Joachim and Sacrament delta near San Francisco
• Captured in large dams and reservoirs all over mountain areas (Hetch Hetchy, Owens valley)
• Transported to cities, e.g. los angeles
• Also transported from Colorado river
• Some desalination in San Diego
• Now water recycling
• Some boreholes, wells

Who uses

• Mainly irrigated farming in central valley (80%)
• Huge increase in demand - pop growth
• Industrial use in factories
• Recreational use, sailing, swimming
• Environmental use for survival of ecosystems, e.g. smelt fish in danger of extinction

Management;

• Conserve in farming
• Drip irrigation instead of sprinklers
• Low water needing crops, e.g. almonds, citrus fruits
• Line irrigation canals with plastic to prevent underground loss
• Conserve domestically
• Low flow showers and toilets and machines
• High water pricing
• Change garden plants to plants that used less water
• Water recycling
• Desalination
• Build more dams, reservoirs, to catch more water