The Aral Sea is the fourth largest lake in the world after the Caspian Sea, Lakes Superior and Victoria. The name Aral Sea appeared at the end of the 17th century. In the Turkic language it sounded like “Aral Tengiz” and meant “island sea” in connection with the island of Barsakelmes, the island Vozrozhdeniya and others formed as a result of lowering the water level.
Not so long ago, by geological standards, about 2.2–2.0 million years ago, two differently directed tectonic processes took place in this place. And if the Ustyurt plateau with calcareous bottom sediments of the Sarmatian Sea gradually rose up, then the territory to the east of it gradually sank and in its place the Aral cavity arose. The second most important processes were deflation and erosion. As a result of the combined activity of tectonic processes, deflation and erosion, a cavity of the Aral Sea 150 meters deep appeared.
Scientists are still arguing how many cycles of transgressions and regressions there were in the history of the Aral Sea. Most believe that the Aral Sea has undergone from five to seven transgressions, the most powerful of which are at the highest elevations, reaching up to 72-73 meters above sea level.
In the Neolithic era, the Amu Darya river broke into Sarykamysh and created a vast lake here. From Lake Sarykamysh, water in the amount of approximately 20% of the Amu Darya river flow flowed through Uzboy into the Caspian Sea. This flow lasted during the 4th-3rd millennium BC and periodically in the 2nd - early 1st millennium BC.
The modern period of watering of the Aral Sea began in the 1st millennium BC, when the flow of the Amu Darya river through the Uzboy into the Caspian Sea stopped, and it began gradually develop the main flow into the Aral Basin along with the Syr Darya river, which flowed through the Zhanadarya and Kuvandarya. About 2600–3000 years ago, the ancient Aral transgression took place. The abundance of water resources and fertile sediments of the Amu Darya river valley led to the emergence in the 8th century BC ancient agricultural state of Khorezm.
Subsequently, periods of watering and shallowing of the Aral Sea alternated with enviable regularity. The transgression is replaced by a deep regression, the sea level dropped to levels close to +30 m. It probably occurred about 1500 years ago and was associated with the rapid development of irrigated agriculture, the creation of irrigation systems and the formation of freshwater lakes with large areas of evaporation in the Amu Darya delta. This regression was called Oxian. The sea retreated to the west and remained only in the trench near the chinks, the central part turned into shallow water densely overgrown with reeds. Under Lake Oxia, the Aral Sea was first mentioned by a Roman historian of the 4th century AD Amyanna Marcellina.
Following the Oxian regression, the Novo-Aral transgression began about 1200 years ago. During this period, the level of the Aral, with minor fluctuations, was at levels of +50- +54 m. But in certain periods associated with breakthroughs of the Amu Darya into Sarykamysh, the Aral lowered its level to +34, +38, +45 m. The remains of two settlements and mausoleums of the Golden Horde era found on the bottom of the Aral Sea are probably associated with these periods of shallowing. The Kerderi Mausoleum, approximately dating from the 11th - 14th centuries, and the fortified settlement of Aral-Asar, dating from the 14th century, were located for a long time at the bottom of the Aral Sea at a depth of 20 meters.
The last stage of development of the Aral transgression begins in the 17th century, when the Amu Darya completely began to flow into the Aral. At the beginning of the 19th century, the level of the Aral Sea was low again. In 1845 and after the 1860s, some increases in sea level were noted in the Baltic altitude system.
In 1849, a Russian expedition led by A. Butakov conducted the first scientific expedition to the Aral Sea. The artist was T. Shevchenko, a famous Ukrainian writer and poet. They mapped the coastline, measured depths, and carried out meteorological and astronomical observations. In 1850, the first map of the Aral Sea was published in Russia.
During the Soviet era, the scale of fish production grew every year. The fishermen's nets caught Aral salmon, barbel, bream, carp, roach, pike perch and other types of fish. In the best years, up to 50 thousand tons of fish were caught in the Aral Sea.
In the early 80s of the 19th century, the level of water became especially low, and therefore researchers of those times came to conclusion about a progressive decrease in water in Central Asia. However, as soon as these conclusions were made, the level of the Aral Sea began to rise. Subsequently, increases and decreases in water levels in the Aral alternated almost every year, but the amplitude of fluctuations during the half-century of the late 19th and early 20th centuries did not exceed three meters between marks of +50 and +53 m due to the alternation of high-water and dry years. This continued until 1961.
In 1961, the natural development of the Aral Sea ended and the subsequent retreat of the sea can be called a period of catastrophic technogenic regression. This is primarily due to the growing needs of agriculture for water, as well as the construction of the Karakum Canal on the Amu Darya - the first part of the canal was opened in 1959. In 1962, when the canal was completed, it began to take 45% of all water from the Amu Darya. Over 33 years, the level has fallen from +53 to +36 m and continues to decline.
As the latest calculations show, the change in the level of the Aral Sea occurs by 23% due to the loss of water for irrigation and household needs, 15% due to climatic factors, 62% of the water goes into the bowels of the earth.
Looking into the recent geological past, it is possible to accurately predict the future of the Aral Sea and its development, when it again turns into a source of powerful soil deflation. Loose soil with a high salt content, picked up by dust storms, falls on the oases of the Aral Sea region and Khorezm.
As of 1998, four stages of sedimentation were distinguished: terrigenous-carbonate, gypsum, mirabilite and halite. The first has already ended, the second stage of accumulation of gypsum sediments began in the early 90s and is currently ongoing. The large sea has finally lost the flow of the Amu Darya river and exists only due to its nutrition by groundwater and scanty precipitation. With high salinity of residual lakes, the intensity of their evaporation will noticeably decrease. The rate of drying of the Aral Sea is significantly slowing down due to a reduction in the water surface area. Due to the high salinity, all the fish in the Aral Sea died and now it is inhabited only by brine shrimp.
The sea split into two parts: the Big Sea (southern part) and the Small Sea (northern part). In future, with the most optimistic forecasts of a rate of sea level decline of 0.2 m per year, it should be expected that by 2040, in place of the Aral Sea, several isolated lakes with a mineralization of more than 200 g/l will appear. They will occupy the central part of the Big Sea, a trench near the chinks and deep areas of the Small Sea. When the level of these lakes drops to 26 m and the salinity exceeds 200 g/l, mirabilite will precipitate in them.
There are no exact measurements for 2024 yet, but approximately the water level is 28 meters above sea level, and the area is only 7 thousand square kilometers. The water level dropped by 26 meters, and the area shrank by 10 times!
This is the fate of the Aral and its future, which has been repeated many times in the past. Someday the Aral Sea will become full again, but, unfortunately, this will not happen in our century. In place of the sea, the Aralkum desert with its own ecosystem was formed, which people are trying to improve by planting saxaul and other desert plant species.
The Small Sea, known as the northern Aral, is located on the territory of Kazakhstan. In 1989, it separated from the Greater Aral and retained acceptable salinity due to the flow of the Syr Darya. Since the early 1990s, attempts have been made to block the outflow of Syr Darya waters into the Greater Aral to raise the water level, reduce its salinity, and also improve the environmental situation in the country through the construction of an earthen dam. In 2005, in order to preserve the Small Aral Sea, a new Kok-Aral dam and Aklak hydroelectric complex were built to regulate the flow of the Syr Darya.
