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The history of the Aral Sea

11 Sep

Aral riverAral Sea endothelial salt lake in Central Asia, on the limit between Kazakhstan and Uzbekistan. Since the 1960s of the XX century the sea level (and the amount of water in it) is declining rapidly due to diversion of water from the main supply of the Amudarya and Syrdarya.

Prior to the shoaling of the Aral Sea was the fourth largest lake in the world. Over-extraction of water for irrigation of agricultural land in the world has made the fourth-largest lake, the sea, above the rich life in the barren desert.

What is happening to the Aral Sea – a real ecological disaster, the blame for which lies with the Soviet government? At the moment the shrinking Aral Sea has gone 100 miles from his former coastline near the town of Muynak in Uzbekistan.

Almost all of the water flow into the Aral Sea provides the Amu Darya and Syr Darya. For millennia, it happened that the channel Amu took the side of the Aral Sea (the Caspian Sea), causing a reduction in the size of the Aral Sea. However, with the return of the river Aral invariably restored in the former borders. Today on intensive irrigation of cotton and rice fields takes up a large part of the flow of the two rivers, which dramatically reduces the flow of water to their delta and, accordingly, in the sea itself. Precipitation in the form of rain and snow, as well as underground sources give the Aral Sea is much less water than it is lost by evaporation, resulting in a water volume of the lake, the sea is reduced and the salinity increases.

In the Soviet Union, the deteriorating state of the Aral Sea was hidden for decades, until 1985, when MS Gorbachev made this ecological disaster public. In the late 1980’s. level had dropped so much that the whole sea was divided into two parts: the northern Small Aral Sea and the southern Big Aral. By 2007, in the southern part clearly recorded deep western and eastern shallow waters, as well as the remains of a small single bay. Large Aral volume decreased from 708 to only 75 km3, and the salinity of the water increased from 14 to more than 100 g / l. With the collapse of the USSR in 1991, the Aral Sea was divided between the newly formed states: Kazakhstan and Uzbekistan. Thus, ended the grand Soviet plan for the transfer of water here far Siberian rivers, and spread competition for melting water. We can only that failed to complete the project for the transfer of Siberian Rivers, because we do not know what would have followed this disaster.

Drainage water coming from the fields in the direction of Syrdarya and Amudarya caused deposits of pesticides and various other agricultural chemicals that appear in some places to 54 thousand miles? Former sea bottom covered with salt. Dust storms spread salt, dust and chemicals at a distance of 500 km. Sodium bicarbonate, sodium chloride and sodium sulfate airborne and destroy or slow the development of natural vegetation and crops. The local population suffers from a high incidence of respiratory disease, anemia, cancer of the larynx, and esophagus, as well as digestive disorders. Frequent liver and kidney disease, eye disease.

The drying up of the Aral Sea had severe consequences. Due to a sharp decrease in river flow ceased spring floods, who supplied the marshes the Amudarya and Syrdarya rivers with fresh water and fertile sediments. The number of fish species living there dropped from 32 to 6 – the result of increasing salinity, loss of spawning and feeding areas (which are preserved in the main only in river deltas). In 1960 fish catch reached 40 tons, by the mid-1980s. Local commercial fishing simply ceased to exist, and was lost for more than 60 thousand related jobs. The most common inhabitant remained Black Sea turbot, adapted to life in the sea water and brought here back in 1970. However, by 2003, in the Big Aral Sea disappeared and she could not stand salinity of more than 70 g / l – in 2-4 times more than usual for her marine environment.

Shipping in the Aral Sea has stopped because water receded for many kilometers from the major local ports: the city of Aral in the north and in the south of the city Muynak. And to maintain the navigability of the increasingly long channels to ports was too costly. With lowering of the water level in both parts of the Aral Sea has fallen and the water table, thus accelerating the process of desertification areas. By the mid-1990s. instead of lush green trees, shrubs and grasses on the banks of the old sea could be seen only occasional tufts xerophytes and halophytes – plants adapted to saline soils and dry habitats. That it retained only half the native species of mammals and birds. Within 100 miles of the original coastline climate change: it became hotter in summer and colder in winter, reduced the level of humidity (or decreased rainfall), and decreased the length of the growing season were more likely to occur drought

Despite the vast watershed, the Aral Sea is almost does not get water because of the irrigation canals, which, as the photo below, taking water from the Amu Darya and Syr Darya for hundreds of kilometers of their flow through several countries. Among other consequences – the extinction of many species of animals and plants

However, if you turn to the history of the Aral Sea, the sea has dried up, and the back again in the old bank. So, what was the Aral last few centuries and how to change its size?

In the historical period there were significant fluctuations in the level of the Aral Sea. So, the bottom of the indentation found the remains of trees that grew on the site. In the middle of the Cenozoic era (21 million years ago) was connected to the Aral Sea Caspian Sea. Until 1573 the sleeve Uzboy Amu into the Caspian Sea, and the river Turgay – the Aral Sea. The map, compiled Greek scholar Claudius Ptolemy (1800 years ago), shows the Aral Sea and the Caspian Sea, in the Zarafshan River flow into the Caspian and Amu Darya. In the late 16th and early 17th centuries, due to a drop in sea level formed the island Barsakelmes, Kaskakulan, Kozzhetpes, Uyaly, Biyiktau, Renaissance. River Zhanadarya from 1819 to 1823 Kuandarya ceased to fall into the Aral Sea. Since the beginning of systematic observations (XIX century) and to the middle of XX century, the Aral Sea level changes were insignificant. In the 1950s, the Aral Sea was the fourth largest lake in the world, covering approximately 68 thousand km.kv, its length is 426 km, width – 284 km, maximum depth – 68 m

In 1930 began large-scale construction of irrigation canals in Central Asia, which is particularly intensified in the early 1960s. Since the 1960s, the sea was shallow because the water of the rivers flowing into it, in ever increasing volumes diverted to irrigation. From 1960 to 1990, the area of irrigated land in Central Asia increased from 4.5 million to 7 million hectares. Needs of the economy of the region in the water increased from 60 to 120 km? per year, of which 90% is used for irrigation. Since 1961, the sea level dropped off at an increasing rate from 20 to 80-90 cm / year. Until the 1970s, lived in the Aral Sea 34 species of fish, 20 of them have commercial value. In 1946, the Aral Sea were captured 23 thousand tons of fish in 1980, the figure was 60,000 tons. On the Kazakh part of the Aral Sea fisheries were 5, 1 fish cannery, 45 fish reception points for Uzbek (Karakalpakstan) – 5 of Fisheries, 1 fish cannery, fish reception of more than 20 points.

In 1989, the sea split into two isolated reservoirs – Northern (Small) and South (Large) Aral Sea. For 2003, the surface area of the Aral Sea is about a quarter of the original, and the amount of water – about 10%. By the beginning of the 2000s, the absolute level of water in the sea dropped to a mark of 31 m, 22 m below the initial level of the late 1950s. Fishing is preserved only in the Small Aral Sea, and in the Big Aral Sea due to its high salinity of all the fish died. In 2001, the South Aral Sea was divided into western and eastern parts. In 2008, the Uzbek part of the Sea held exploration (prospecting oil and gas fields). Contractor – the company “Petro Alliance”, the customer – the government of Uzbekistan. In summer 2009, the eastern part of the South (Greater) Aral Sea dried up.

Indented sea left a 54 km2 of dry sea bottom covered with salt, and in some places even deposits of various pesticides and other agricultural chemicals, washed once runoff from local fields. Currently, severe storms spread salt, dust and chemicals at a distance of 500 km. The north and north-east winds adversely affect Saharan Amudarya river delta – the most densely populated, the most economically and ecologically important part of the entire region. Airborne sodium bicarbonate, sodium chloride and sodium sulfate kill or slow the development of natural vegetation and agricultural crops – a bitter irony, that the fields of crop irrigation brought the Aral Sea to its current sorry state.

As pointed out by medical experts, the local population suffers from high incidence of respiratory disease, anemia, cancer of the throat and esophagus, as well as digestive disorders. Frequent liver and kidney disease, not to mention the eye disease.

 
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Posted by on September 11, 2012 in Earth, Historical, Human, Island, Mysterious, Nature, Ocean

 

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