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Desertification in South-west
USA…read more

Slide 2

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Physical causes of desertification:
· The climate of SW USA includes a range of different
extremes: 100-125 f in the summer to sub-zero in the
northernmost region.
· There are 2 deserts in the Southwest region of the US:
- Mojave and Sonoran deserts.
· Effect of climate change is causing dry zones to
expand. ­ As in the SW region the winter storms
primarily replenish groundwater, as the summer temp
gets longer, this leads to water stress.
· Air temp has increased in past century = reduction in
· Temp increases = reduction in soil mosture…read more

Slide 3

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Link climate and water…read more

Slide 4

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Human causes of desertification:
· SW region including some of the fastest growing states
(e.g. Las Vegas in Nevada will reach 3.5 m residents by
2012 ­ 330,000 moved there in past 5 years).
· Yet large cities such as Phoenix, exist due to large
water transfer projects. (e.g. Pumping aquifers).
· Las Vegas depends on Colorado river yet due to
reduced snowpack (climate) there will be shortages. It
is technically a desert.
· Water from agriculture is going to urban usage. In
summer this increases due to e.g. Air conditioning and
lawns.…read more

Slide 5

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Slide 6

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Human causes of desertification:
· Population growth = Increased energy
consumption = Increased water consumption (8
gallons of water powers 1kw in Arizona).
· Biggest usage of groundwater goes towards
IRRIGATION : Around 80% groundwater used for it
in Arizona and other western states.
· Groundwater has to be used in conjunction with
Colorado and Rio Grande to meet demands.
· Mining groundwater has led to subsidence in
some areas (e.g. San Joaquin valley).…read more

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