Which ocean does the Caspian Sea belong to? Caspian Sea: description, depth, width, interesting facts. Recreational resources of the Caspian Lake

The Caspian Sea is the most big lake On the Earth. It is called the sea because of its size and bed, which is built like an ocean basin. The area is 371,000 square meters, the depth is 1025 m. The list of rivers flowing into the Caspian Sea includes 130 names. The largest of them are: Volga, Terek, Samur, Sulak, Ural and others.

Caspian Sea

It took 10 million years before the Caspian Sea was formed. The reason for its formation is that the Sarmatian Sea, having lost contact with the World Ocean, was divided into two bodies of water, which were called the Black and Caspian Seas. Between the latter and the World Ocean there are thousands of kilometers of waterless route. It is located at the junction of two continents - Asia and Europe. Its length in the north-south direction is 1200 km, west-east - 195-435 km. The Caspian Sea is an internal endorheic basin of Eurasia.

Near the Caspian Sea, the water level is below the level of the World Ocean, and it is also subject to fluctuations. According to scientists, this is due to many factors: anthropogenic, geological, climatic. Currently, the average water level reaches 28 m.

The river network and wastewater are unevenly distributed along the coast. A few rivers flow into part of the sea from the northern side: Volga, Terek, Ural. From the west - Samur, Sulak, Kura. The east coast is characterized by the absence of permanent watercourses. Differences in space in the flow of water that rivers bring to the Caspian Sea are important geographical feature of this reservoir.

Volga

This river is one of the largest in Europe. In Russia it ranks sixth in size. In terms of drainage area, it is second only to Siberian rivers flowing into the Caspian Sea, such as the Ob, Lena, Yenisei, and Irtysh. The source from where the Volga begins is taken to be a spring near the village of Volgoverkhovye, Tver Region, on the Valdai Hills. Now at the source there is a chapel that attracts the attention of tourists who are proud to step over the very beginning of the mighty Volga.

A small fast stream gradually gains strength and becomes a huge river. Its length is 3690 km. The source is 225 m above sea level. Among the rivers flowing into the Caspian Sea, the largest is the Volga. Its path runs through many regions of our country: Tver, Moscow, Nizhny Novgorod, Volgograd and others. The territories through which it flows are Tatarstan, Chuvashia, Kalmykia and Mari El. The Volga is home to millionaire cities - Nizhny Novgorod, Samara, Kazan, Volgograd.

Volga Delta

The main channel of the river is divided into channels. A certain shape of the mouth is formed. It's called delta. Its beginning is the place where the Buzan branch separates from the Volga river bed. The delta is located 46 km north of the city of Astrakhan. It includes channels, branches, and small rivers. There are several main branches, but only Akhtuba is navigable. Among all the rivers of Europe, the Volga has the largest delta, which is a rich fishing region in this basin.

It lies 28 m lower than ocean level. The mouth of the Volga is the location of the southernmost Volga city of Astrakhan, which in the distant past was the capital of the Tatar Khanate. Later, at the beginning of the 18th century (1717), Peter 1 gave the city the status of “capital of the Astrakhan province.” During his reign, the city's main attraction, the Assumption Cathedral, was built. Its Kremlin is made of white stone brought from the capital of the Golden Horde, Saraya. The mouth is divided by branches, the largest of which are: Bolda, Bakhtemir, Buzan. Astrakhan is a southern city located on 11 islands. Today it is a city of shipbuilders, sailors and fishermen.

The Volga currently needs protection. For this purpose, a reserve was established in the place where the river flows into the sea. The delta of the Volga, the largest river flowing into the Caspian Sea, is replete with unique flora and fauna: sturgeon, lotuses, pelicans, flamingos and others. Immediately after the revolution of 1917, a law was passed on their protection by the state as part of the Astrakhan Nature Reserve.

Sulak River

It is located in Dagestan and flows through its territory. It is fed by the waters of melted snow that flow from the mountains, as well as by tributaries: Maly Sulak, Chvakhun-bak, Akh-su. Water also enters Sulak through a canal from the Aksai and Aktash rivers.

The source is formed by the confluence of two rivers that originate in the basins: Didoiskaya and Tushinskaya. The length of the Sulak River is 144 km. Her pool has enough large area- 15,200 square meters. It flows through a canyon with the same name as a river, then through the Akhetlinsky gorge and finally reaches the plane. Rounding the Agrakhan Bay from the south, Sulak flows into the sea.

The river provides Kaspiysk and Makhachkala with drinking water; hydroelectric power stations, urban settlements Sulak and Dubki are located on it, as well as small town Kizilyurt.

Samur

The river received this name not by chance. The name translated from the Caucasian language (one of them) means “middle”. Indeed, the waterway along the Samur River marks the border between the states of Russia and Azerbaijan.

The sources of the river are glaciers and springs originating in the spurs of the Caucasus Range on the northeastern side, not far from Guton Mountain. The height above sea level is 3200 m. Samur has a length of 213 km. The height at the headwaters and the mouth differs by three kilometers. The drainage basin has an area of ​​almost five thousand square meters.

The places where the river flows are narrow gorges located between high mountains made of clayey shales and sandstones, which is why the water here is muddy. The Samur basin has 65 rivers. Their length reaches 10 km or more.

Samur: valley and its description

The valley of this river in Dagestan is the most densely populated area. Near the mouth is Derbent, the oldest city in the world. The banks of the Samur River are home to twenty or more species of relict flora. Endemic, endangered and rare species listed in the Red Book.

In the river delta there is a relict forest, which is the only one in Russia. The liana forest is a fairy tale. Huge trees of the rarest and most common species grow here, intertwined with vines. The river is rich in valuable fish species: mullet, pike perch, pike, catfish and others.

Terek

The river received its name from the Karachay-Balkar peoples who lived along its banks. They called it “Terk Suu”, which means “swift water”. The Ingush and Chechens called it Lomeki - “mountain water”.

The beginning of the river is the territory of Georgia, the Zigla-Khokh glacier is a mountain located on the slope of the Caucasus ridge. It is located under glaciers all year round. One of them melts when sliding down. A small stream is formed, which is the source of the Terek. It is located at an altitude of 2713 m above sea level. The length of the river flowing into the Caspian Sea is 600 km. When it flows into the Caspian Sea, the Terek is divided into many branches, resulting in the formation of a vast delta, its area is 4000 square meters. In some places it is very swampy.

The riverbed in this place changed several times. The old branches have now been converted into canals. The middle of the last century (1957) was marked by the construction of the Kargaly hydroelectric complex. It is used to supply water to the canals.

How is the Terek replenished?

The river has a mixed supply, but for the upper reaches, water from melting glaciers plays an important role; they fill the river. In this regard, 70% of the flow occurs in spring and summer, that is, at this time the water level in the Terek is highest, and the lowest is in February. The river freezes if the winters are characterized by a harsh climate, but the ice cover is unstable.

The river is not clean and transparent. The turbidity of the water is high: 400-500 g/m3. Every year the Terek and its tributaries pollute the Caspian Sea, pouring into it from 9 to 26 million tons of various suspended matter. This is explained by the rocks that make up the shores, which are clayey.

Estuary Terek

The Sunzha is the largest tributary flowing into the Terek, the lower reaches of which are measured from this river. By this time, the Terek flows for a long time through the flat terrain, leaving the mountains located behind the Elkhotov Gate. The bottom here is made of sand and pebbles, the current slows down, and in some places stops altogether.

The mouth of the Terek River has an unusual appearance: the bed here is raised above the valley, along appearance resembles a canal, which is fenced with a high embankment. The water level becomes higher than the land level. This phenomenon is due to natural causes. Since the Terek is a turbulent river, it brings sand and stones in large quantities from the Caucasus Range. Considering that the current in the lower reaches is weak, some of them settle here and do not reach the sea. For residents of this area, sediment is both a threat and a blessing. When they are washed away by water, floods of great destructive power occur, this is very bad. But in the absence of floods, the soils become fertile.

Ural River

In ancient times (until the second half of the 18th century) the river was called Yaik. It was renamed in the Russian way by decree of Catherine the Second in 1775. Just at this time, the Peasant War, the leader of which was Pugachev, was suppressed. The name has been preserved to this day in the Bashkir language, and is official in Kazakhstan. The Urals are the third longest in Europe; only the Volga and Danube are larger rivers.

The Urals originate in Russia, on the slope of the Round Hill of the Uraltau ridge. The source is a spring gushing out of the ground at an altitude of 637 m above sea level. At the beginning of its journey, the river flows in a north-south direction, but after encountering a plateau along the way, it makes a sharp turn and continues to flow in a north-west direction. However, beyond Orenburg its direction changes again to the southwest, which is considered the main one. Having overcome a winding path, the Urals flows into the Caspian Sea. The length of the river is 2428 km. The mouth is divided into branches and tends to become shallow.

The Ural is a river along which the natural water boundary between Europe and Asia passes, with the exception of the upper reaches. It is an inland European river, but its headwaters are east of Ural ridge are the territory of Asia.

The importance of the Caspian rivers

The rivers flowing into the Caspian Sea are of great importance. Their waters are used for human and animal consumption, domestic, agricultural and industrial needs. Hydroelectric power stations are built on rivers, the energy of which is in demand by people for various purposes. River basins are full of fish, algae, and shellfish. Even in ancient times, people chose river valleys for future settlements. And now cities and towns are being built on their banks. The rivers are plied by passenger and transport ships, performing important tasks for transporting passengers and cargo.

, Kazakhstan, Turkmenistan, Iran, Azerbaijan

Geographical position

Caspian Sea - view from space.

The Caspian Sea is located at the junction of two parts of the Eurasian continent - Europe and Asia. The length of the Caspian Sea from north to south is approximately 1200 kilometers (36°34"-47°13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46°-56° c. d.).

The Caspian Sea is conventionally divided according to physical and geographical conditions into 3 parts - Northern Caspian, Middle Caspian and Southern Caspian. The conditional border between the Northern and Middle Caspian runs along the line of the island. Chechen - Cape Tyub-Karagansky, between the Middle and Southern Caspian Sea - along the line of the island. Residential - Cape Gan-Gulu. The area of ​​the Northern, Middle and Southern Caspian Sea is 25, 36, 39 percent, respectively.

Coast of the Caspian Sea

Coast of the Caspian Sea in Turkmenistan

The territory adjacent to the Caspian Sea is called the Caspian region.

Peninsulas of the Caspian Sea

• Ashur-Ada
• Garasu
• Zyanbil
• Khara-Zira
• Sengi-Mugan
• Chygyl

Bays of the Caspian Sea

• Russia (Dagestan, Kalmykia and Astrakhan region) - in the west and northwest, the length of the coastline is about 1930 kilometers
• Kazakhstan - in the north, northeast and east, the length of the coastline is about 2320 kilometers
• Turkmenistan - in the southeast, the length of the coastline is about 650 kilometers
• Iran - in the south, the length of the coastline is about 1000 kilometers
• Azerbaijan - in the southwest, the length of the coastline is about 800 kilometers

Cities on the Caspian Sea coast

On the Russian coast there are cities - Lagan, Makhachkala, Kaspiysk, Izberbash and the most Southern City Russia Derbent. Astrakhan is also considered a port city of the Caspian Sea, which, however, is not located on the shores of the Caspian Sea, but in the Volga delta, 60 kilometers from north coast Caspian Sea.

Physiography

Area, depth, volume of water

The area and volume of water in the Caspian Sea varies significantly depending on fluctuations in water levels. At a water level of −26.75 m, the area is approximately 371,000 square kilometers, the volume of water is 78,648 cubic kilometers, which is approximately 44% of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface level. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated from the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. The predominant plants in the Caspian Sea are algae - blue-green, diatoms, red, brown, characeae and others, and flowering plants - zoster and ruppia. In origin, the flora is predominantly of Neogene age, but some plants were brought into the Caspian Sea by humans deliberately or on the bottoms of ships.

History of the Caspian Sea

Origin of the Caspian Sea

Anthropological and cultural history of the Caspian Sea

Finds in the Khuto u cave south coast The Caspian Sea indicates that man lived in these areas approximately 75 thousand years ago. The first mentions of the Caspian Sea and the tribes living on its coast are found in Herodotus. Around the V-II centuries. BC e. Saka tribes lived on the Caspian coast. Later, during the period of settlement of the Turks, in the period of the 4th-5th centuries. n. e. Talysh tribes (Talysh) lived here. According to ancient Armenian and Iranian manuscripts, Russians sailed the Caspian Sea from the 9th-10th centuries.

Research of the Caspian Sea

Research of the Caspian Sea was started by Peter the Great, when, on his order, an expedition was organized in 1714-1715 under the leadership of A. Bekovich-Cherkassky. In the 1720s, hydrographic research was continued by the expedition of Karl von Werden and F. I. Soimonov, and later by I. V. Tokmachev, M. I. Voinovich and other researchers. At the beginning of the 19th century, instrumental surveys of the shores were carried out by I. F. Kolodkin, in the mid-19th century. - instrumental geographical survey under the direction of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary research on the hydrology and hydrobiology of the Caspian Sea was carried out under the leadership of N. M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power, geological research by I.M. Gubkin and other Soviet geologists was actively carried out in the Caspian Sea, mainly aimed at searching for oil, as well as research to study the water balance and level fluctuations of the Caspian Sea.

Economy of the Caspian Sea

Mining of oil and gas

Many oil and gas fields are being developed in the Caspian Sea. Proven oil resources in the Caspian Sea are about 10 billion tons, total oil and gas condensate resources are estimated at 18-20 billion tons.

Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf near Baku. In the second half of the 19th century, oil production began on an industrial scale on the Absheron Peninsula, and then in other territories.

Shipping

Shipping is developed in the Caspian Sea. There are ferry crossings on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with Sea of ​​Azov through the Volga, Don and Volga-Don Canal rivers.

Fishing and seafood production

Fishing (sturgeon, bream, carp, pike perch, sprat), caviar production, as well as seal fishing. More than 90 percent of the world's sturgeon catch occurs in the Caspian Sea. In addition to industrial mining, illegal fishing of sturgeon and their caviar flourishes in the Caspian Sea.

Recreational resources

Natural environment of the Caspian coast with sandy beaches, mineral waters and healing mud in the coastal zone creates good conditions for rest and treatment. At the same time, according to the degree of development of resorts and the tourism industry Caspian coast noticeably loses to the Black Sea coast of the Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coasts of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. Azerbaijan is actively developing resort area in the Baku region. A world-class resort has now been created in Amburan, another modern tourist complex is being built in the area of ​​the village of Nardaran, holidays in the sanatoriums of the villages of Bilgah and Zagulba are very popular. A resort area is also being developed in Nabran, in northern Azerbaijan. However high prices, in general, the low level of service and lack of advertising lead to the fact that Caspian resorts almost no foreign tourists. The development of the tourism industry in Turkmenistan is hampered by a long-term policy of isolation; in Iran, Sharia law, due to which mass recreation foreign tourists on the Caspian coast of Iran is impossible.

Ecological problems

Environmental problems of the Caspian Sea are associated with water pollution as a result of oil production and transportation on the continental shelf, the flow of pollutants from the Volga and other rivers flowing into the Caspian Sea, the life activity of coastal cities, as well as the flooding of individual objects due to rising levels of the Caspian Sea. Predatory production of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeon and to forced restrictions on their production and export.

International status of the Caspian Sea

Legal status of the Caspian Sea

After the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of resources of the Caspian shelf - oil and gas, as well as biological resources. Negotiations took place for a long time between Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran insisted on dividing the Caspian by one fifth between all Caspian states.

In relation to the Caspian Sea, the key is the physical-geographical circumstance that it is a closed inland body of water that does not have a natural connection with the World Ocean. Accordingly, the norms and concepts of international maritime law, in particular, the provisions of the UN Convention on the Law of the Sea of ​​1982, should not be automatically applied to the Caspian Sea. Based on this, in relation to the Caspian Sea it would be unlawful to apply such concepts as “territorial sea”, “exclusive economic zone", "continental shelf", etc.

The current legal regime of the Caspian Sea was established by the Soviet-Iranian treaties of 1921 and 1940. These treaties provide for freedom of navigation throughout the sea, freedom of fishing with the exception of ten-mile national fishing zones and a ban on vessels flying the flag of non-Caspian states sailing in its waters.

Negotiations about legal status The Caspian Sea is currently ongoing.

Delineation of sections of the Caspian seabed for subsoil use

The Russian Federation concluded an agreement with Kazakhstan on delimiting the bottom of the northern part of the Caspian Sea in order to exercise sovereign rights to subsoil use (dated July 6, 1998 and the Protocol thereto dated May 13, 2002), an agreement with Azerbaijan on delimiting adjacent areas of the bottom of the northern part of the Caspian Sea (dated September 23, 2002), as well as the trilateral Russian-Azerbaijani-Kazakh agreement on the junction point of the demarcation lines of adjacent sections of the Caspian Sea bottom (dated May 14, 2003), which established geographical coordinates dividing lines limiting the areas of the seabed within which the parties exercise their sovereign rights in the field of exploration and production of mineral resources.

Caspian Sea - the largest lake on Earth, endorheic, located at the junction of Europe and Asia, called a sea because of its size, as well as because its bed is composed of oceanic-type crust. The water in the Caspian Sea is salty, from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data it was 27.16 m below sea level. The area of ​​the Caspian Sea is currently approximately 371,000 km², the maximum depth is 1025 m.

Geographical position

The Caspian Sea is located at the junction of two parts of the Eurasian continent - Europe and Asia. The length of the Caspian Sea from north to south is approximately 1200 kilometers (36°34"-47°13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46°-56° c. d.). The Caspian Sea is conventionally divided according to physical and geographical conditions into 3 parts - the Northern Caspian, the Middle Caspian and the Southern Caspian. The conditional border between the Northern and Middle Caspian runs along the line of the island. Chechen - Cape Tyub-Karagansky, between the Middle and Southern Caspian Sea - along the line of the island. Residential - Cape Gan-Gulu. The area of ​​the Northern, Middle and Southern Caspian Sea is 25, 36, 39 percent, respectively.

The length of the coastline of the Caspian Sea is estimated at approximately 6500-6700 kilometers, with islands - up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low-lying and smooth. In the northern part, the coastline is indented by water channels and islands of the Volga and Ural deltas, the banks are low and swampy, and the water surface in many places is covered with thickets. On east coast Limestone coasts predominate, adjacent to semi-deserts and deserts. The most winding shores are on the western coast in the area of ​​the Absheron Peninsula and on the eastern coast in the area of ​​the Kazakh Gulf and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian region.

Peninsulas of the Caspian Sea

Large peninsulas of the Caspian Sea:

• Agrakhan Peninsula
• The Absheron Peninsula, located on the western coast of the Caspian Sea in the territory of Azerbaijan, at the northeastern end Greater Caucasus, on its territory the cities of Baku and Sumgayit are located
• Buzachi
• Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory is the city of Aktau
• Miankale
• Tyub-Karagan

Islands of the Caspian Sea

There are about 50 large and medium-sized islands in the Caspian Sea with total area approximately 350 square kilometers. Largest islands:

• Ashur-Ada
• Garasu
• Boyuk-Zira
• Zyanbil
• Cure Dashi
• Khara-Zira
• Ogurchinsky
• Sengi-Mugan
• Seal
• Seal Islands
• Chechen
• Chygyl

Bays of the Caspian Sea

Large bays of the Caspian Sea:

• Agrakhan Bay
• Kizlyar Bay
• Dead Kultuk (formerly Komsomolets, formerly Tsesarevich Bay)
• Kaydak
• Mangyshlaksky
• Kazakh
• Kenderli
• Turkmenbashi (bay) (formerly Krasnovodsk)
• Turkmen (bay)
• Gizilagach (formerly Kirov Bay)
• Astrakhan (bay)
• Hasan-kuli
• Gizlar
• Hyrcanus (formerly Astarabad)
• Anzeli (formerly Pahlavi)
• Kara-Bogaz-Gol

Rivers flowing into the Caspian Sea-130 rivers flow into the Caspian Sea, of which 9 rivers have a delta-shaped mouth. Large rivers flowing into the Caspian Sea are the Volga, Terek, Sulak, Samur (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Atrek (Turkmenistan), Sefidrud (Iran) and others. The largest river flowing into the Caspian Sea is the Volga, its average annual flow is 215-224 cubic kilometers. The Volga, Ural, Terek, Sulak and Emba provide up to 88-90% of the annual flow into the Caspian Sea.

Physiography

Area, depth, volume of water- the area and volume of water in the Caspian Sea varies significantly depending on fluctuations in water level. At a water level of −26.75 m, the area is approximately 371,000 square kilometers, the volume of water is 78,648 cubic kilometers, which is approximately 44% of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface level. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated from the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations- the water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past three thousand years, the magnitude of the change in the water level of the Caspian Sea has reached 15 meters. According to archeology and written sources, a high level of the Caspian Sea is recorded at the beginning of the 14th century. Instrumental measurements of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out since 1837, during which time the highest water level was recorded in 1882 (−25.2 m), the lowest in 1977 (−29.0 m), with Since 1978, the water level has risen and in 1995 reached −26.7 m; since 1996, a downward trend has emerged again. Scientists associate the reasons for changes in the water level of the Caspian Sea with climatic, geological and anthropogenic factors. But in 2001, sea level began to rise again, and reached −26.3 m.

Water temperature- water temperature is subject to significant latitudinal changes, most clearly expressed in winter, when the temperature varies from 0-0.5 °C at the ice edge in the north of the sea to 10-11 °C in the south, that is, the water temperature difference is about 10 ° C. For shallow water areas with depths less than 25 m, the annual amplitude can reach 25-26 °C. On average, the water temperature off the west coast is 1-2 °C higher than that on the east, and in the open sea the water temperature is 2-4 °C higher than off the coasts.

Water composition- the salt composition of the waters of the closed Caspian Sea differs from the oceanic one. There are significant differences in the ratios of concentrations of salt-forming ions, especially for waters in areas directly influenced by continental runoff. The process of metamorphization of sea waters under the influence of continental runoff leads to a decrease in the relative content of chlorides in the total amount of salts of sea waters, an increase in the relative amount of carbonates, sulfates, calcium, which are the main components in chemical composition river waters. The most conservative ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ions. In the Caspian Sea, the content of calcium and magnesium cations is almost two times higher than in the Sea of ​​Azov, and the sulfate anion is three times higher.

Bottom relief- the relief of the northern part of the Caspian Sea is a shallow undulating plain with banks and accumulative islands, the average depth of the Northern Caspian Sea is 4-8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle Caspian. The Middle Caspian is quite deep, the water depth in the Derbent depression reaches 788 meters. The Absheron threshold separates the Middle and Southern Caspian Seas. The Southern Caspian is considered deep-sea; the water depth in the South Caspian depression reaches 1025 meters from the surface of the Caspian Sea. Shell sands are widespread on the Caspian shelf, deep-sea areas are covered with silty sediments, and in some areas there is an outcrop of bedrock.

Climate- the climate of the Caspian Sea is continental in the northern part, temperate in the middle and subtropical in the southern part. In winter average monthly temperature air temperature varies from −8…−10 in the northern part to +8…+10 in the southern part, in summer - from +24…+25 in the northern part to +26…+27 in the southern part. The maximum temperature of +44 degrees was recorded on the east coast. The average annual precipitation is 200 millimeters, ranging from 90-100 millimeters in the arid eastern part to 1,700 millimeters along the southwestern subtropical coast. Evaporation of water from the surface of the Caspian Sea is about 1000 millimeters per year, the most intense evaporation in the area of ​​the Absheron Peninsula and in the eastern part of the South Caspian Sea is up to 1400 millimeters per year. The average annual wind speed is 3-7 meters per second, the wind rose is dominated by north winds. In the autumn and winter months, winds become stronger, with wind speeds often reaching 35-40 meters per second. The most windy territories are the Absheron Peninsula, the environs of Makhachkala and Derbent, where the most high wave 11 meters high.

Currents- water circulation in the Caspian Sea is associated with drainage and winds. Because the most of The drainage falls on the Northern Caspian Sea, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current divides into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

Economic development of the Caspian Sea

Mining of oil and gas-Many oil and gas fields are being developed in the Caspian Sea. Proven oil resources in the Caspian Sea are about 10 billion tons, total oil and gas condensate resources are estimated at 18-20 billion tons. Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf near Baku. In the second half of the 19th century, oil production began on an industrial scale on the Absheron Peninsula, and then in other territories. In 1949, oil was first produced at Neftyanye Kamni from the bottom of the Caspian Sea. So, on August 24 of this year, Mikhail Kaverochkin’s team began drilling a well, which yielded the long-awaited oil on November 7 of the same year. In addition to oil and gas production, salt, limestone, stone, sand, and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.

Shipping- Shipping is developed in the Caspian Sea. There are ferry crossings on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with the Sea of ​​Azov through the Volga, Don and Volga-Don Canal rivers.

Fishing and seafood production-fishing (sturgeon, bream, carp, pike perch, sprat), caviar production, as well as seal fishing. More than 90 percent of the world's sturgeon catch occurs in the Caspian Sea. In addition to industrial mining, illegal fishing of sturgeon and their caviar flourishes in the Caspian Sea.

Legal status of the Caspian Sea- after the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of the resources of the Caspian shelf - oil and gas, as well as biological resources. For a long time, negotiations were ongoing between the Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran insisted on dividing the Caspian by one-fifth between all Caspian states. The current legal regime of the Caspian was established by the Soviet-Iranian treaties of 1921 and 1940 These treaties provide for freedom of navigation throughout the sea, freedom of fishing with the exception of ten-mile national fishing zones and a ban on vessels flying the flag of non-Caspian states sailing in its waters. Negotiations on the legal status of the Caspian Sea are currently ongoing.

The Caspian Sea is the largest lake on our planet, which is located in a depression of the earth’s surface (the so-called Aral-Caspian Lowland) on the territory of Russia, Turkmenistan, Kazakhstan, Azerbaijan and Iran. Although they consider it as a lake, because it is not connected with the World Ocean, but by the nature of the formation processes and history of origin, by its size, the Caspian Sea is a sea.

The area of ​​the Caspian Sea is about 371 thousand km 2. The sea, stretching from north to south, has a length of about 1200 km and an average width of 320 km. The length of the coastline is about 7 thousand km. The Caspian Sea is located 28.5 m below the level of the World Ocean and its greatest depth is 1025 m. There are about 50 islands in the Caspian Sea, mostly small in area. The large islands include such islands as Tyuleniy, Kulaly, Zhiloy, Chechen, Artem, Ogurchinsky. There are also many bays in the sea, for example: Kizlyarsky, Komsomolets, Kazakhsky, Agrakhansky, etc.

The Caspian Sea is fed by more than 130 rivers. Largest quantity water (about 88% of the total flow) is brought by the rivers Ural, Volga, Terek, Emba, which flow into northern part seas. About 7% of the runoff comes from large rivers Kura, Samur, Sulak and small ones flowing into the sea on the west coast. The rivers Heraz, Gorgan, and Sefidrud flow into the southern Iranian coast, bringing only 5% of the flow. Not a single river flows into the eastern part of the sea. The water in the Caspian Sea is salty, its salinity ranges from 0.3‰ to 13‰.

Shores of the Caspian Sea

The shores have different landscapes. The shores of the northern part of the sea are low and flat, surrounded by low-lying semi-desert and somewhat elevated desert. In the south, the shores are partly low-lying, bordered by the coastal lowland small area, behind which the Elburz ridge runs along the coast, which in some places comes close to the coast. In the west, the Greater Caucasus ranges approach the coast. In the east there is an abrasion coast, carved out of limestone, and semi-desert and desert plateaus approach it. The coastline changes greatly due to periodic fluctuations in water levels.

The climate of the Caspian Sea is different:

Continental in the north;

Moderate in the middle

Subtropical in the south.

At the same time, there are severe frosts and snowstorms on the northern shore, while fruit trees and magnolias bloom on the southern shore. In winter, strong storm winds rage at sea.

On the coast of the Caspian Sea there are big cities, ports: Baku, Lankaran, Turkmenbashi, Lagan, Makhachkala, Kaspiysk, Izberbash, Astrakhan, etc.

The fauna of the Caspian Sea is represented by 1809 species of animals. More than 70 species of fish are found in the sea, including: herring, gobies, stellate sturgeon, sturgeon, beluga, white fish, sterlet, pike perch, carp, bream, roach, etc. Of the marine mammals, only the smallest in the world, the Caspian seal, is found in the lake. not found in other seas. The Caspian Sea lies on the main migratory route of birds between Asia, Europe and the Middle East. Every year, about 12 million birds fly over the Caspian Sea during migration, and another 5 million usually winter here.

Vegetable world

The flora of the Caspian Sea and its coast includes 728 species. Basically, the sea is inhabited by algae: diatoms, blue-greens, red, characeae, brown and others, of the flowering ones - rupee and zoster.

The Caspian Sea is rich in natural resources; many oil and gas fields are being developed in it; in addition, limestone, salt, sand, stone and clay are also mined here. The Caspian Sea is connected by the Volga-Don Canal with the Sea of ​​Azov, and shipping is well developed. A lot of different fish are caught in the reservoir, including more than 90% of the world's sturgeon catch.

The Caspian Sea is also a recreation area; on its shores there are holiday homes, tourist centers and sanatoriums.

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V. N. MIKHAILOV

The Caspian Sea is the largest on the planet closed lake. This body of water is called the sea for its huge size, brackish water and a regime similar to the sea. The level of the Caspian Sea-lake lies much lower than the level of the World Ocean. At the beginning of 2000, it was around -27 abs. m. At this level, the area of ​​the Caspian Sea is ~ 393 thousand km2 and the volume of water is 78,600 km3. The average and maximum depths are 208 and 1025 m, respectively.

The Caspian Sea stretches from south to north (Fig. 1). The Caspian Sea washes the shores of Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran. The reservoir is rich in fish, its bottom and shores are rich in oil and gas. The Caspian Sea has been studied quite well, but many mysteries remain in its regime. The most characteristic feature of a reservoir is the instability of the level with sharp drops and rises. The last increase in the level of the Caspian Sea occurred before our eyes from 1978 to 1995. It gave rise to many rumors and speculation. Numerous publications appeared in the press talking about catastrophic floods and an environmental disaster. They often wrote that the rise in the level of the Caspian Sea led to the flooding of almost the entire Volga delta. What is true in the statements made? What is the reason for this behavior of the Caspian Sea?

WHAT HAPPENED TO THE CASPIAN IN THE XX CENTURY

Systematic observations of the level of the Caspian Sea began in 1837. In the second half of the 19th century, the average annual values ​​of the Caspian Sea level were in the range from – 26 to – 25.5 abs. m and had a slight downward trend. This trend continued into the 20th century (Fig. 2). In the period from 1929 to 1941, sea level dropped sharply (by almost 2 m - from - 25.88 to - 27.84 abs. m). In subsequent years, the level continued to fall and, having decreased by approximately 1.2 m, reached in 1977 the lowest level during the observation period - 29.01 abs. m. Then the sea level began to rise rapidly and, having risen by 2.35 m by 1995, reached 26.66 abs. m. In the next four years, the average sea level dropped by almost 30 cm. Its average levels were - 26.80 in 1996, - 26.95 in 1997, - 26.94 in 1998 and - 27.00 abs. m in 1999.

The decrease in sea level in 1930-1970 led to the shallowing of coastal waters, the extension of the coastline towards the sea, the formation wide beaches. The latter was perhaps the only positive consequence of the drop in level. There were significantly more negative consequences. As the level dropped, the areas of feeding grounds for fish stocks in the northern Caspian Sea decreased. The shallow-water estuarine coastal area of ​​the Volga began to quickly become overgrown with aquatic vegetation, which worsened the conditions for the passage of fish to spawn in the Volga. Fish catches have sharply decreased, especially valuable species: sturgeon and sterlet. Shipping began to suffer due to the fact that the depths in the approach channels decreased, especially near the Volga delta.

The rise in levels from 1978 to 1995 was not only unexpected, but also led to even greater negative consequences. After all, both the economy and the population of coastal areas have already adapted to the low level.

Many sectors of the economy began to suffer damage. Significant areas were in the flood and flood zone, especially in the northern (plain) part of Dagestan, Kalmykia and the Astrakhan region. The cities of Derbent, Kaspiysk, Makhachkala, Sulak, Kaspiysky (Lagan) and dozens of other smaller settlements suffered from the rise in level. Significant areas of agricultural land are flooded and submerged. Roads and power lines, engineering structures of industrial enterprises and public utilities are being destroyed. A threatening situation has developed with fish farming enterprises. Abrasion processes in the coastal zone and the influence of surges have intensified sea ​​water. In recent years, the flora and fauna of the seaside and coastal zone of the Volga delta have suffered significant damage.

Due to the increase in depth in the shallow waters of the Northern Caspian and the reduction in the areas occupied by aquatic vegetation in these places, the conditions for the reproduction of stocks of anadromous and semi-anadromous fish and the conditions for their migration to the delta for spawning have somewhat improved. However, the predominance of negative consequences from rising sea levels has led to talk of an environmental catastrophe. The development of measures to protect national economic facilities and settlements from the advancing sea began.

HOW UNUSUAL IS THE CURRENT BEHAVIOR OF THE CASPIAN SEA?

Research into the life history of the Caspian Sea can help answer this question. Of course, there are no direct observations of the past regime of the Caspian Sea, but there is archaeological, cartographic and other evidence for historical time and the results of paleogeographic studies covering a longer period.

It has been proven that during the Pleistocene (the last 700-500 thousand years), the level of the Caspian Sea underwent large-scale fluctuations in the range of about 200 m: from -140 to + 50 abs. m. During this period of time, four stages are distinguished in the history of the Caspian Sea: Baku, Khazar, Khvalyn and Novo-Caspian (Fig. 3). Each stage included several transgressions and regressions. The Baku transgression occurred 400-500 thousand years ago, sea level rose to 5 abs. m. During the Khazar stage, there were two transgressions: early Khazar (250-300 thousand years ago, maximum level 10 abs. m) and late Khazar (100-200 thousand years ago, highest level -15 abs. m). The Khvalynian stage in the history of the Caspian Sea included two transgressions: the largest during the Pleistocene period, the Early Khvalynian (40-70 thousand years ago, maximum level 47 absolute meters, which is 74 m higher than the modern one) and the Late Khvalynian (10-20 thousand years ago, rise level up to 0 abs. m). These transgressions were separated by the deep Enotayev regression (22-17 thousand years ago), when sea level dropped to -64 abs. m and was 37 m lower than the modern one.

Rice. 4. Fluctuations in the level of the Caspian Sea over the past 10 thousand years. P is the natural range of fluctuations in the level of the Caspian Sea under climatic conditions characteristic of the sub-Atlantic Holocene era (risk zone). I-IV - stages of the New Caspian transgression; M - Mangyshlak, D - Derbent regression

Significant fluctuations in the level of the Caspian Sea also occurred during the New Caspian stage of its history, which coincided with the Holocene (the last 10 thousand years). After the Mangyshlak regression (10 thousand years ago, the level dropped to – 50 abs. m), five stages of the New Caspian transgression were noted, separated by small regressions (Fig. 4). Following fluctuations in sea level—its transgressions and regressions—the outline of the reservoir also changed (Fig. 5).

Over historical time (2000 years), the range of change in the average level of the Caspian Sea was 7 m – from – 32 to – 25 abs. m (see Fig. 4). The minimum level in the last 2000 years was during the Derbent regression (VI-VII centuries AD), when it decreased to – 32 abs. m. During the time elapsed after the Derbent regression, the average sea level changed in an even narrower range - from – 30 to – 25 abs. m. This range of level changes is called the risk zone.

Thus, the level of the Caspian Sea has experienced fluctuations before, and in the past they were more significant than in the 20th century. Such periodic fluctuations are a normal manifestation of the unstable state of a closed reservoir with variable conditions at the outer boundaries. Therefore, there is nothing unusual in the decrease and increase in the level of the Caspian Sea.

Fluctuations in the level of the Caspian Sea in the past, apparently, did not lead to irreversible degradation of its biota. Of course, sharp drops in sea level created temporary unfavorable conditions, for example for fish stocks. However, as the level rose, the situation corrected itself. Natural conditions coastal zone (vegetation, bottom animals, fish) experience periodic changes along with sea level fluctuations and, apparently, have a certain margin of stability and resistance to external influences. After all, the most valuable sturgeon stock has always been in the Caspian basin, regardless of sea level fluctuations, quickly overcoming temporary deterioration in living conditions.

Rumors that rising sea levels caused floods throughout the Volga delta were not confirmed. Moreover, it turned out that the increase in water levels even in the lower part of the delta is inadequate to the magnitude of the sea level rise. The increase in water level in the lower part of the delta during the low-water period did not exceed 0.2-0.3 m, and during the flood it almost did not appear at all. At the maximum level of the Caspian Sea in 1995, the backwater from the sea extended along the deepest branch of the delta, Bakhtemiru, no more than 90 km, and along other branches no more than 30 km. Therefore, only the islands on the seashore and the narrow coastal strip of the delta were flooded. Flooding in the upper and middle parts of the delta was associated with high floods in 1991 and 1995 (which is a normal phenomenon for the Volga delta) and with the unsatisfactory condition of protective dams. The reason for the weak influence of sea level rise on the regime of the Volga delta is the presence of a huge shallow coastal zone, which dampens the impact of the sea on the delta.

As for the negative impact of sea level rise on the economy and life of the population in the coastal zone, the following should be recalled. At the end of the last century, sea level was higher than it is now, and this was not perceived as ecological catastrophy. And before the level was even higher. Meanwhile, Astrakhan has been known since the middle of the 13th century, and here in the 13th - mid-16th centuries the capital of the Golden Horde, Sarai-Batu, was located. These and many others settlements on the Caspian coast did not suffer from high levels, since they were located on elevated places and during abnormal flood levels or surges, people temporarily moved from low places to higher places.

Why is it that now the consequences of sea level rise, even to lower levels, are perceived as a catastrophe? The reason for the enormous damage suffered by the national economy is not the rise in level, but the thoughtless and short-sighted development of a strip of land within the mentioned risk zone, freed (as it turned out, temporarily!) from under sea level after 1929, that is, when the level decreased below the mark - 26 abs. m. The buildings erected in the risk zone, naturally, turned out to be flooded and partially destroyed. Now that a territory developed and polluted by humans is being flooded, a dangerous situation is indeed being created. ecological situation, the source of which is not natural processes, but unreasonable economic activity.

ABOUT THE REASONS FOR CASPIAN LEVEL FLUCTUATIONS

When considering the reasons for fluctuations in the level of the Caspian Sea, it is necessary to pay attention to the confrontation between two concepts in this area: geological and climatic. Significant contradictions in these approaches emerged, for example, at the international conference "Caspian-95".

According to the geological concept, the causes of changes in the level of the Caspian Sea include processes of two groups. The processes of the first group, according to geologists, lead to changes in the volume of the Caspian basin and, as a consequence, to changes in sea level. Such processes include vertical and horizontal tectonic movements of the earth’s crust, accumulation bottom sediments and seismic phenomena. The second group includes processes that, as geologists believe, affect the underground flow into the sea, either increasing or decreasing it. Such processes are called periodic extrusion or absorption of waters that saturate bottom sediments under the influence of changing tectonic stresses (changes in periods of compression and extension), as well as technogenic destabilization of the subsurface caused by oil and gas production or underground nuclear explosions. It is impossible to deny the fundamental possibility of the influence of geological processes on the morphology and morphometry of the Caspian basin and underground flow. However, at present, the quantitative connection of geological factors with fluctuations in the level of the Caspian Sea has not been proven.

There is no doubt that tectonic movements played a decisive role in the initial stages of the formation of the Caspian basin. However, if we take into account that the Caspian Sea basin is located within a geologically heterogeneous territory, which results in a periodic rather than linear nature of tectonic movements with repeated changes in sign, then one should hardly expect a noticeable change in the capacity of the basin. The tectonic hypothesis is also not supported by the fact that coastlines New Caspian transgressions on all sections of the Caspian coast (with the exception of certain areas within the Absheron archipelago) are at the same level.

There is no reason to believe that the cause of fluctuations in the level of the Caspian Sea is a change in the capacity of its depression due to the accumulation of sediments. The rate of filling of the basin with bottom sediments, among which the main role is played by river discharges, is estimated, according to modern data, to be about 1 mm/year or less, which is two orders of magnitude less than the currently observed changes in sea level. Seismic deformations, which are noted only near the epicenter and attenuate at close distances from it, cannot have any significant effect on the volume of the Caspian basin.

As for the periodic large-scale discharge of groundwater into the Caspian Sea, its mechanism is still unclear. At the same time, this hypothesis is contradicted, according to E.G. Maevu, firstly, the undisturbed stratification of silt waters, indicating the absence of noticeable migrations of water through the thickness of bottom sediments, and secondly, the absence of proven powerful hydrological, hydrochemical and sedimentation anomalies in the sea, which should have accompanied large-scale discharge of groundwater that could influence changes in the level of the reservoir.

The main proof of the insignificant role of geological factors at present is the convincing quantitative confirmation of the plausibility of the second, climatic, or more precisely, water-balance concept of Caspian level fluctuations.

CHANGES IN THE COMPONENTS OF THE CASPIAN WATER BALANCE AS THE MAIN REASON FOR FLUCTUATIONS IN ITS LEVEL

For the first time, fluctuations in the level of the Caspian Sea were explained by changes climatic conditions(more specifically river flow, evaporation and precipitation on the sea surface) also E.Kh. Lentz (1836) and A.I. Voeikov (1884). Later, the leading role of changes in the components of the water balance in sea level fluctuations was proven again and again by hydrologists, oceanologists, physical geographers and geomorphologists.

The key to most of the studies mentioned is the development of a water balance equation and the analysis of its components. The meaning of this equation is as follows: the change in the volume of water in the sea is the difference between the incoming (river and underground runoff, precipitation on the sea surface) and outgoing (evaporation from the sea surface and outflow of water into the Kara-Bogaz-Gol Bay) components of the water balance. The change in the level of the Caspian Sea is the quotient of the change in the volume of its waters divided by the area of ​​the sea. The analysis showed that the leading role in the water balance of the sea belongs to the ratio of the runoff of the Volga, Ural, Terek, Sulak, Samur, Kura rivers and visible or effective evaporation, the difference between evaporation and precipitation on the sea surface. Analysis of the components of the water balance revealed that the largest contribution (up to 72% of the variance) to the level variability is made by the influx of river water, and more specifically, the zone of runoff formation in the Volga basin. As for the reasons for the change in the Volga runoff itself, many researchers believe that they are associated with the variability of atmospheric precipitation (mainly winter) in the river basin. And the precipitation regime, in turn, is determined by atmospheric circulation. It has long been proven that the latitudinal type of atmospheric circulation contributes to an increase in precipitation in the Volga basin, and the meridional type contributes to a decrease.

V.N. Malinin revealed that the root cause of moisture entering the Volga basin should be sought in the North Atlantic, and specifically in the Norwegian Sea. It is there that an increase in evaporation from the sea surface leads to an increase in the amount of moisture transferred to the continent and, accordingly, to an increase in atmospheric precipitation in the Volga basin. The latest data on the water balance of the Caspian Sea, obtained by employees of the State Oceanographic Institute R.E. Nikonova and V.N. Bortnik, are given with clarifications by the author in table. 1. These data provide convincing evidence that the main causes of both the rapid drop in sea level in the 1930s and the sharp rise in 1978-1995 were changes in river flow, as well as visible evaporation.

Bearing in mind that river flow is one of the main factors influencing the water balance and, as a consequence, the level of the Caspian Sea (and the Volga flow provides at least 80% of the total river flow into the sea and about 70% of the incoming part of the Caspian water balance), It would be interesting to find a connection between sea level and the flow of the Volga alone, measured most accurately. Direct correlation of these quantities does not give satisfactory results.

However, the connection between sea level and Volga runoff is clearly visible if we take into account the river flow not for every year, but take the ordinates of the difference integral runoff curve, that is, the sequential sum of normalized deviations of annual runoff values ​​from the long-term average value (norm). Even a visual comparison of the course of the average annual levels of the Caspian Sea and the difference integral curve of the Volga runoff (see Fig. 2) allows us to identify their similarities.

Over the entire 98-year period of observations of the Volga runoff (the village of Verkhnee Lebyazhye at the top of the delta) and sea level (Makhachkala), the correlation coefficient between the sea level and the ordinates of the difference integral runoff curve was 0.73. If we discard years with small changes in level (1900-1928), then the correlation coefficient increases to 0.85. If we take for analysis a period with a rapid decline (1929-1941) and a rise in level (1978-1995), then the overall correlation coefficient will be 0.987, and separately for both periods 0.990 and 0.979, respectively.

The above calculation results fully confirm the conclusion that during periods of a sharp decrease or rise in sea level, the levels themselves are closely related to the runoff (more precisely, to the sum of its annual deviations from the norm).

A special task is to assess the role of anthropogenic factors in fluctuations in the level of the Caspian Sea, and first of all, the reduction of river flow due to irreversible losses due to the filling of reservoirs, evaporation from the surface of artificial reservoirs, and water intake for irrigation. It is believed that since the 40s, irreversible water consumption has steadily increased, which has led to a reduction in the influx of river water to the Caspian Sea and an additional decrease in its level compared to the natural one. According to V.N. Malinin, by the end of the 80s, the difference between the actual sea level and the restored (natural) reached almost 1.5 m. At the same time, the total irrecoverable water consumption in the Caspian basin was estimated in those years at 36-45 km3/year (of which the Volga accounted for about 26 km3/year). If it were not for the withdrawal of river flow, sea level rise would have begun not in the late 70s, but in the late 50s.

The increase in water consumption in the Caspian basin by 2000 was predicted first to 65 km3/year, and then to 55 km3/year (36 of which were accounted for by the Volga). Such an increase in irrevocable losses of river flow should have reduced the level of the Caspian Sea by more than 0.5 m by 2000. In connection with assessing the impact of irreversible water consumption on the level of the Caspian Sea, we note the following. Firstly, estimates in the literature of the volumes of water intake and losses due to evaporation from the surface of reservoirs in the Volga basin are apparently significantly overestimated. Secondly, forecasts for the growth of water consumption turned out to be erroneous. The forecasts included the pace of development of water-consuming sectors of the economy (especially irrigation), which not only turned out to be unrealistic, but also gave way to a decline in production in recent years. In fact, as A.E. points out. Asarin (1997), by 1990, water consumption in the Caspian basin was about 40 km3/year, and has now decreased to 30-35 km3/year (in the Volga basin up to 24 km3/year). Therefore, the “anthropogenic” difference between the natural and actual sea level is currently not as great as predicted.

ABOUT POSSIBLE FLUCTUATIONS IN THE CASPIAN SEA LEVEL IN THE FUTURE

The author does not set himself the goal of analyzing in detail the numerous forecasts of fluctuations in the level of the Caspian Sea (this is an independent and difficult task). The main conclusion from assessing the results of forecasting Caspian level fluctuations can be drawn as follows. Although the forecasts were based on completely different approaches (both deterministic and probabilistic), there was not a single reliable forecast. The main difficulty in using deterministic forecasts based on the sea water balance equation is the lack of development of the theory and practice of ultra-long-term climate change forecasts over large areas.

When sea levels dropped in the 1930s to 1970s, most researchers predicted they would fall further. In the last two decades, when sea level rise began, most forecasts predicted an almost linear and even accelerating rise in sea level to -25 and even -20 abs. m and higher at the beginning of the 21st century. Three circumstances were not taken into account. Firstly, the periodic nature of fluctuations in the level of all closed reservoirs. The instability of the Caspian Sea level and its periodic nature is confirmed by an analysis of its current and past fluctuations. Secondly, at a sea level close to – 26 abs. m, the flooding of large bays-sors on the north-eastern coast of the Caspian Sea - Dead Kultuk and Kaydak, as well as low-lying areas in other places on the coast - will begin to flood, which have dried out at low levels. This would lead to an increase in the area of ​​shallow waters and, as a consequence, to an increase in evaporation (up to 10 km3/year). At a higher sea level, the outflow of water into Kara-Bogaz-Gol will increase. All this should stabilize or at least slow down the level increase. Thirdly, level fluctuations under the conditions of the modern climatic era (the last 2000 years), as shown above, are limited by the risk zone (from – 30 to – 25 abs. m). Taking into account the anthropogenic decrease in runoff, the level is unlikely to exceed the level of 26-26.5 abs. m.

The decrease in average annual levels in the last four years by a total of 0.34 m may indicate that in 1995 the level reached its maximum (- 26.66 abs. m), and a change in the trend of the Caspian level. In any case, the prediction is that sea level is unlikely to exceed 26 absolute. m, apparently, is justified.

In the 20th century, the level of the Caspian Sea changed within 3.5 m, first falling and then rising sharply. This behavior of the Caspian Sea is the normal state of a closed reservoir as an open dynamic system with variable conditions at its inlet.

Each combination of incoming (river flow, precipitation on the sea surface) and outgoing (evaporation from the surface of a reservoir, outflow into the Kara-Bogaz-Gol Bay) components of the Caspian water balance corresponds to its own level of equilibrium. Since the components of the water balance of the sea also change under the influence of climatic conditions, the level of the reservoir fluctuates, trying to reach an equilibrium state, but never reaches it. Ultimately, the trend of changes in the Caspian Sea level in given time depends on the ratio of precipitation minus evaporation in the catchment area (in the basins of the rivers feeding it) and evaporation minus precipitation above the reservoir itself. There is actually nothing unusual about the recent rise in the Caspian sea level by 2.3 m. Such level changes have happened many times in the past and have not caused irreparable damage to the natural resources of the Caspian Sea. The current rise in sea level has become a disaster for the economy of the coastal zone only because of the unreasonable development by man of this risk zone.

Vadim Nikolaevich Mikhailov, Doctor of Geographical Sciences, Professor of the Department of Land Hydrology, Faculty of Geography, Moscow State University, Honored Scientist of the Russian Federation, Full Member of the Academy of Water Sciences. Area of ​​scientific interests – hydrology and water resources, interaction of rivers and seas, deltas and estuaries, hydroecology. Author and co-author of about 250 scientific works, including 11 monographs, two textbooks, four scientific and methodological manuals.