In the recent past the Aral Sea represented a unique natural object – saline lake-sea with a surface area covering more than 60 thousand square kilometers and a volume of about 1000 cubical kilometers, and having high biological productivity.
The Aral Sea is located in northern deserted part of Central Asia, within the borders of Uzbekistan and Kazakhstan, and related to the river basin of the same name. By size the Aral Sea occupied the fourth place in the world among lakes with just the Caspian Sea, Lake Superior (Canada, USA), Lake Victoria (Tanzania, Kenya, Uganda) ahead and the second place among intercontinental enclosed lakes keeping only the Caspian Sea ahead; that is why people referred it as the Sea. The surface water level of the Aral Sea in natural conditions used to reach 53m above the sea level, which is almost 80m higher than the present level of the Caspian Sea. It had sizes stood for 428km in length and 234 km in width, with a maximum depth of 69 m; water volume accounted for 1064 km3.
Continentality and aridity are the main features of climate fluctuations in the area. In northern parts of the region the climate is continental; in southern parts it is subtropical. The average annual amplitudes of air temperature reach 33–36 degrees. During the long hot summer, average temperatures reach 26–33 degrees Celsius. In winter cold air masses penetrate and reduce the temperature. In northern deserts the average January temperature is 10-15 degrees below; in the south it could be above 0. The annual precipitation accounts for 20–120mm.
In the period from 1960 to 1990 the major programmes on land development were undertaken in the region; as a result, the territory of irrigated lands doubled and reached 8 mln ha, while the annual water withdrawals increased from 63 to 117km3. The Aral Sea started to shallow every year, because waters of the rivers of Syrdarya and Amudarya were practically used to satisfy the economic needs. The desert water reservoir was almost deprived of water flow and became a giant vaporizer.
As a result, by 1989 the annual river flow to the Aral Sea reduced dramatically reaching only 9-12km3, and constitutes much less in present period, the water area divided in the two basic, but not equal parts – Large sea and Small sea – connected through the strait of Berg. By 2009 the sea water level dropped down about 25m, the water surface reduced more than 2 times, and the water volume reduced 10 times, indicators compared to those of 1960s.
|Satellite image of the Aral Sea, 2009 and 1960s shoreline - National Aeronautics and Space Administration, 2010|
The first islands to connect with the land, since the Aral Sea started to shrink, were the islands of Akpetkin; and the gulfs that used to separate them turned into salt-marshes. In 1990 the island of Kokaral disappeared; it linked up with the land, and the gulf of Saryshyganak vanished. The gulf of Berg which used to separate Large Aral from Small Aral also disappeared. The area of other islands started to grow. In 10 years all the islands linked up between each other and divided Large Aral into two parts: western part and eastern part.
|Dynamics of water surface decrease in 2000s - National Aeronautics and Space Administration, 2008|
|Most recent satelite image of the Aral Sea - National Aeronautics and Space Administration, 2010|
As a result of the Aral Sea drying out and of the influence of other processes (the economic decline of 1990s, the population growth in the region, climate change impact) the ecological and socio-economic situation in the Aral Sea region deteriorated catastrophically, and became essentially complicated in the whole Region of the Aral Sea Basin.
According to most researchers and experts, restoration of the whole sea to the level of 1960s is seen as impossible in near future. In 1990-s it had been decided to make an attempt for saving at least Northern part of the sea (Small sea or Small Aral) within the “Syrdarya Control and Northern Aral Sea” Project. Within the First phase of the project implementation in 2003-2005 Kazakhstan built Kokaral dam from Kokaral peninsula to the Syrdarya delta, which separated Small Aral from the rest part (Large Aral); hydrotechnical gate in a dam can pass the excess of water in order to regulate the level of the reservoir.
|Kok-Aral dam (straight of Berg), 2006 - Western Michigan University, 2009. Source: Japan Aerospace Exploration Agency (JAXA), 2006|
As a result the flow from Syrdarya River accumulates in Small Aral; water level in Small Aral reached 40-42m. Water salinity reduced which allows breeding some commercial varieties of fish. In 2007 fish catch in Small Aral amounted 1910 tons, of which share of flounder is 640 tons, while rest of it presented freshwater species.
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