Western USA: Water supply

4.3 What factors affect the supply and use of resources?

Background: Western USA covers 60% of the US, holding 40% of the population and recieving 25% of rainfall - Therefore demand exceeds the supply.

Factors affecting supply:

• Low amounts of rainfall because of the Meditteranean climate.
• Excessive pumping of aquifers.
• Deforestation has reduced evapotranspiration.
• High evaporation from…