Aral Sea. The Overview.
The Aral Sea (Uzbek: Orol Dengizi; Russian: Аральскοе Мοре) is a landlocked endorheic basin in Central Asia; it lies between Kazakhstan (Aktobe and Kyzylorda provinces) in the north and Karakalpakstan, an autonomous region of Uzbekistan, in the south. The name roughly translates as “Sea of Islands”, referring to more than 1,500 islands of one hectare or more that once dotted its waters. There are now three lakes in the Aral Basin: the North Aral Sea and the eastern and western basins of the South Aral Sea. The maximum depth of the sea is 102 feet (31 m).
It once covered some 26,300 sq mi (68,000 sq km) and was the fourth largest inland body of water in the world.
The shallow Aral Sea was formerly the world’s fourth largest body of inland water. It nestles in the climatically inhospitable heart of Central Asia, to the east of the Caspian Sea. The Aral Sea is of great interest and increasing concern to scientists because of the remarkable shrinkage of its area and volume in the second half of the 20th century. This change is due primarily to the diversion (for purposes of irrigation) of the riverine waters of the Syr Darya and Amu Darya, which discharge into the Aral Sea and are its main sources of inflowing water.
Climate
The Aral Sea area is characterized by a desert-continental climate of wide-ranging air temperatures, cold winters, hot summers, and sparse rainfall. The rate of precipitation—an annual average of 4 inches (100 mm) in all—is only a tiny fraction of the lake’s traditional rate of evaporation. The most significant factors affecting the water balance of the Aral Sea are river flow (accounting for approximately four-fifths of inflow) and evaporation, which formerly took out each year about the same amount of water that the rivers brought in.
Climate may quite considerably influence the long-term variation in the sea’s water level. Over the centuries, variations have exceeded 20 feet (6 metres), while annual and seasonal variations of between 10 feet (3 metres) and less than a foot have been recorded.
History
The Aral Sea depression was formed toward the beginning of the Pleistocene Epoch (about 1,600,000 years ago), when the Earth’s crust subsided and the hollow was filled with water—some of which came from the Syr Darya. In the late Pleistocene Epoch (from about 140,000 until about 10,000 years ago) the depression was inundated for the first time by the Amu Darya, which had temporarily changed its course from the Caspian to the Aral Sea. From the Pleistocene Epoch, the rivers’ combined flow maintained a high water level.
The sea’s northern shore—high in some places, low in others—was indented by several large bays. The low-lying and irregular eastern shores were interrupted in the north by the huge delta of the Syr Darya and in the south were bordered by a wide tract of shallow water. The equally vast Amu Darya delta lay on the lake’s southern shore, and along the lake’s western periphery extended the almost unbroken eastern edge of the 820-foot- (250-metre-) high Ustyurt Plateau.
Sixties years of the twentieth century
By 1960, between 20 and 60 cubic kilometers of water were going each year to the land instead of the sea. Most of the sea’s water supply had been diverted, and in the 1960s the Aral Sea began to shrink.
In 1960 was the world’s fourth-largest lake. The surface of the Aral Sea lay 175 feet (53 meters) above sea level and covered an area of 26,300 square miles (68,000 square km) and a volume of 1100 km³. The Aral Sea’s greatest extent from north to south was almost 270 miles (435 km), while that from east to west was just over 180 miles (290 km). Although the average depth was a shallow 53 feet (16 meters) or so, it descended to a maximum of 226 feet (69 meters) off the western shore.
From about 1960 the Aral Sea’s water level was systematically and drastically reduced because of the diversion of water from the Amu Darya and Syr Darya rivers for purposes of agricultural irrigation. As the Soviet government converted large acreages of pastures or untilled lands in Uzbekistan, Kazakhstan, Turkmenistan, and elsewhere into irrigated farmlands by using the waters of the Amu Darya and Syr Darya, the amount of water from these rivers that reached the Aral Sea dropped accordingly. By the 1980s, during the summer months, the two great rivers virtually dried up before they reached the lake. The Aral Sea began to quickly shrink because of the evaporation of its now-unreplenished waters.
Late eighties of the twentieth century
From 1961 to 1970, the Aral’s sea level fell at an average of 20 cm a year; in the 1970s, the average rate nearly tripled to 50–60 cm per year, and by the 1980s it continued to drop, now with a mean of 80–90 cm each year.
By the late 1980s, the lake had lost more than half the volume of its water. The salt and mineral content of the lake rose drastically because of this, making the water unfit for drinking purposes and killing off the once-abundant supplies of sturgeon, carp, barbel, roach, and other fishes in the lake. The fishing industry along the Aral Sea was thus virtually destroyed. The ports of Aral in the northeast and Muynak in the south were now many miles from the lake’s shore. A partial depopulation of the areas along the lake’s former shoreline ensued. The contraction of the Aral Sea also made the local climate noticeably harsher, with more extreme winter and summer temperatures.
By 1989 the Aral Sea had receded to form two separate parts, the “Greater Sea” in the south and the “Lesser Sea” in the north, each of which had a salinity almost triple that of the sea in the 1950s.
By 1992 the total area of the two parts of the Aral Sea had been reduced to approximately 13,000 square miles (33,800 square km), and the mean surface level had dropped by about 50 feet (15 metres). The governments of the states surrounding the Aral tried to institute policies to encourage less water-intensive agricultural practices in the regions south and east of the lake, thus freeing more of the waters of the Amu Darya and the Syr Darya to flow into the lake and to stabilize its water level. These policies succeeded in reducing water usage somewhat, but not to the level necessary to have a significant impact on the amount of water reaching the Aral Sea. In 1994 these same states—Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan—established a joint committee to coordinate efforts to save the Aral Sea. The difficulty of coordinating any plan between these competing states, however, has hampered progress.
The beginning of the nineties the twentieth century to the present day
By the 1990s Aral Sea continued to drop, now with a mean of 80–90 cm each year.
In 1998 was the world’s eighth-largest lake with an area of 28,687 square km.
In 2003, the South Aral Sea was vanishing faster than predicted. In the deepest parts of the sea, the bottom waters are saltier than the top, and not mixing. Thus, only the top of the sea is heated in the summer, and it evaporates faster than would otherwise be expected. Based on the recent data, the eastern part of the South Aral Sea is expected to be gone within 15 years; the western part could last for another 50-125 years.
As of 2004, the Aral Sea’s surface area was only 17,160 square km, 25% of its original size, and a nearly fivefold increase in salinity had killed most of its natural flora and fauna.
By 2007 Aral Sea had declined to 10% of its original size, splitting into three separate lakes, two of which are too salty to support fish. The southern part of the sea (the Large Aral) had increased to levels in excess of 100 g/L.
By comparison, the salinity of ordinary seawater is typically around 35 g/L; the Dead Sea’s salinity varies between 300 and 350 g/L. The once prosperous fishing industry has been virtually destroyed, and former fishing towns along the original shores have become ship graveyards. With this collapse has come unemployment and economic hardship.
Other useful information
Ustyurt Plateau– plateau in Uzbekistan and Kazakhstan, lying between the Aral Sea and the Amu Darya (river) delta in the east and the Mangyshlak (Tupqarghan) Plateau and the Kara-Bogaz-Gol (Garabogazköl; an inlet of the Caspian Sea) in the west. It has an area of about 77,000 square miles (about 200,000 square km) and an average elevation of about 500 feet (about 150 m), rising to a maximum of 1,200 feet (365 m) in the southwest. At its edges it drops steeply to the Aral Sea and the surrounding plain. The plateau consists of a monotonous desert which provides meagre pasture for camels and sheep. Oil and natural-gas deposits lie west of the plateau.
Irrigation – artificial application of water to land and artificial removal of excess water from land, respectively. Some land requires irrigation or drainage before it is possible to use it for any agricultural production; other land profits from either practice to increase production. Some land, of course, does not need either. Although either practice may be, and both often are, used for nonagricultural purposes to improve the environment, this article is limited to their application to agriculture
Fishing Industry. The Aral Sea fishing industry, which in its heyday had employed some 40,000 and reportedly produced one-sixth of the USSR’s entire fish catch, essentially disappeared; so did the muskrat trapping in the deltas of Amu Darya and Syr Darya, which used to yield as much as 500,000 muskrat pelts a year.
Northern river reversal. Starting in the 1960s, a large scale project was proposed to redirect part of the flow of the rivers of the Ob basin to Central Asia over a gigantic canal system. Refilling of the Aral Sea was considered as one of the project’s main goals. However, due to its staggering costs and the negative public opinion in Russia proper, the federal authorities abandoned the project by 1986.
Aralkum is the name given to the new desert that has appeared on the seabed once occupied by the Aral Sea. It lies to the south and east of what remains of the Aral Sea in Uzbekistan and Kazakhstan. The sands of the Aralkum are made up of a salt-marsh consisting of finely-dispersed sea depositions and remnants of mineral deposits, washed away from irrigated fields. The dusts which originate from it contain pollutants. The desert’s location on a powerful east-west airstream has resulted in pesticides in the dust being found in the blood of penguins in Antarctica. Aral dust has also been found in the glaciers of Greenland, the forests of Norway, and the fields of Russia.
Kok-Aral Dam. The plight of the Aral Sea is frequently described as an environmental catastrophe. There is now an ongoing effort in Kazakhstan to save and replenish what remains of the northern part of the Aral Sea (the Small Aral).
A dam project completed in 2005 has raised the water level of this lake by two metres. Salinity has dropped, and fish are again found in sufficient numbers for some fishing to be viable. The outlook for the far larger southern part of the sea (the Large Aral) remains bleak. The 13 kilometer (8 mile) long dam separating the smaller North Aral Sea from its larger, saltier and more polluted southern part was completed in August 2005.
Since completing the dam, Kazakhstan has been able to keep the water from the Syr Darya River in the North Aral Sea. Newly reconstructed, rebuilt, and rehabilitated waterworks along the Syr Darya are increasing the carrying capacity of the river, filling the Northern Aral Sea and benefiting farmers by irrigating their lands. The North Aral Sea’s surface increased from 2,550 square kilometers (985 square miles) in 2003, the ministry said, to 3,300 square kilometers (1,275 square miles) in 2008.
The environmental problems. By the end of the century the Aral had receded into three separate lakes. The level of the sea had dropped to 125 feet (36 metres) above sea level, and the water volume was reduced by 75 percent of what it had been in 1960. Almost no water from the Amu Darya and the Syr Darya reached the sea, and, unless drastic action were taken, it seemed likely that the Aral Sea could disappear within 20 to 30 years, leaving a large desert in its place. The health costs to people living in the area were beginning to emerge. Hardest hit were the Karakalpaks, who live in the southern portion of the region. Exposed seabeds led to dust storms that blew across the region, carrying a toxic dust contaminated with salt, fertilizer, and pesticides. Health problems occurred at unusually high rates—from throat cancers to anemia and kidney diseases. Infant mortality in the region was among the highest in the world.
In the late 1990s an island in the Aral Sea, Vozrozhdenya, became the centre of environmental concern. The Aral Sea derived its name from the Kyrgyz word Aral-denghiz, “Sea of Islands”—an apt designation, as there were more than 1,000 islands of a size of 2.5 acres (1 hectare) or more strewn across its waters. Many of these islands have joined the mainland with the shrinking size of the sea. By 1999 the sea had receded to a level where only 6 miles (10 km) of water were separating Vozrozhdenya Island from the mainland.
This was of special concern because Vozrozhdenya had been a testing ground for Soviet biological weapons during the Cold War. In addition to testing done there on such agents as tularemia and the bubonic plague, hundreds of tons of live anthrax bacteria were buried on the island in the 1980s. In 1999 still-living anthrax spores were discovered on the site, and scientists feared that when the island was no longer surrounded by water, land vertebrates could carry anthrax to populated areas.