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The Aral Sea has been shrinking since the 1960's. In the late 1950's the Soviet government
diverted much of the water from rivers that flowed to the Aral Sea for irrigation of
agriculture for cotton and rice.
By 2007 the sea had declined to just 10% its original size and split into separate lakes and its
level fell by up to 40M.
Fishing industries collapsed and destroyed the livelihoods of 60,000 people.
Health problems are caused by wind-blown salt from the dried out sea bed, which has
contaminated water supplies. Weapons testing, industrial projects and pesticide runoff has
increased water pollution.
Biodiversity of marine life has reduced significantly.
The water table has risen increasing salinity and pollution in the water.
Land has become infertile and people may not be able to feed themselves so will have to
There is now an ongoing effort in Kazakhstan to save and replenish the North Aral Sea. As
part of this effort, a dam project was completed in 2005; in 2008, the water level in this lake
had risen by 24 m. Salinity has dropped, and fish are again found in sufficient numbers for
some fishing to be viable. However, the outlook for the remnants of the South Aral Sea
Much of the Californian is arid with an average precipitation of between 200-500mm
65% of that precipitation is lost though evaporation and precipitation. And 13% flows out to
sea, leaving only 22% for human use.
Rainfall falls in clusters leaving dry arid seasons.
Mountain chains run parallel to the coast and prevent moist air reaching inland. The moist air
is forced upwards and condenses form relief rainfall.
The south only receives 100mm of rainfall due to the rain shadow effect-The Mountains
block the passage of rain-producing weather systems, casting a "shadow" of dryness behind
Most of the major rivers are fed by snowmelt from the Sierra Nevada Mountains.
A high pressure system over the Pacific Ocean blocks moist air currents from reaching
El Nino events bring above average run off and flooding to the south west, while La Nina
events bring drought- droughts have reduced groundwater supplies.
Demand for water is increasing as the population increases; it is predicted to reach 50 million
The demand exceeds supplies.
There is a spatial imbalance, with the south being more heavily populated but only receiving
25% of precipitation.
Demand from Las Vegas, Los Angeles, San Diego, Phoenix, Tucson and San Bernardino.
Due to California's booming economy :
1. Wetland have been drained, natural habitats altered and fish stocks depleted.
2. Waterways have become polluted
3. Over extraction has increased salinity.
4. The Bay Delta region and the Salton Sea have become environmental disaster zones
and the Colorado River has significantly reduced.
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In 1901 the Alamo Canal was begun to bring irrigation water from the Colorado River to the
farmers of the Imperial Valley in Southern California, however much if it passed through
Mexico causing political tensions.
The All American Canal on American land was built to secure a water supply for California's
growing agricultural industry.
Pressures are rising on the Colorado:
1. Mexico takes 10% of the Colorado's flow.
2. States in the lower Basin take 50% and the upper basin falls short of 10%.
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An agricultural sump- it acts as a receiving basin for runoff from irrigated farmlands, formed
when the canal banks collapsed allowing the Colorado River to fill a natural hollow with water
creating a large lake which supported biodiversity. However it is now threatened.
1. Water mixes with pesticides having irrigated cotton plants.
2. Salinization due to evaporation.
3. Eutrophication killing the fish.
4. Industrial pollutants.
The Salton Sea Restoration
Reducing fertiliser run off to prevent eutrophication.…read more
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Dams built will reduce flow to them until their reservoirs fill up they fear they could withhold
water for political reasons.
They reviewed the scheme in 2004 and amended the IIisu dam which damaged surrounding
settlements and the environment. However some people in the Kurdish village were forced
Turkey has agreed to release water from IIisu for Syria.…read more