I rested somehow in the camp. It's no secret that almost every day there are competitions for the entertainment of children and youth. So. Was we have quiz. Question: "Which lake is the largest?" One guy of about fifteen was the first to raise his hand and answer: "Baikal." The strangest thing was that his answer was counted as correct! How so? Isn't the Caspian Sea the most big lake? Now I will explain to you.

How to distinguish the sea from the lake

I will list several signs by which a body of water is defined as a sea.

1. Rivers can flow into the sea.

2. The outer sea has direct access to the ocean.

3. If the sea is inland, then it is connected by straits with other seas or directly with the ocean.

Is the Caspian Sea suitable for the parameters of the sea

Need to check, does the Caspian Sea have signs of a sea. into it really rivers flow, but they flow into many bodies of water: seas, lakes, oceans, and other rivers. The Caspian Sea is surrounded from all sides dry land. Is it really inland sea? Then it should be connected to the Black or Azov seas some strait. Strait too No. Exactly due to the lack of access to the World Ocean, the Caspian Sea is considered a lake.

“But why was it then called the sea, if it is a lake?”- you ask. Answer very simple: due to his large size and salinity. Indeed, The Caspian Sea is several times larger than the Sea of ​​Azov and almost the same size as the Baltic Sea..

Excellent! The quiz issue has been resolved. Soap judge!!!

Well then I told, that the Caspian Sea in fact - lake. Now I want to you provide small compilation interesting facts about this lake.

1. The Caspian Sea is below sea level (-28 m), which once again proves that this is a lake.

2. BC around the lake area lived nomadic Caspian tribes,in honor of which he was nicknamed the Caspian.

3. It the deepest enclosed body of water on the planet.

4. Many believe that the name of the group "Caspian cargo" is related to the Caspian Sea. In a way they are right No). Actually the expression "Caspian cargo" can refer to any illegal cargo.

5.Caspian Sea Good suitable for tourism. Under the USSR, a large number of sanatoriums were built here. Today same here you can see many hotels, water parks and beaches.

The Caspian Sea is the largest lake on planet Earth. It is called the sea because of its size and bed, which is folded 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 was formed. The reason for its formation is that the Sarmatian Sea, which lost its connection with the World Ocean, was divided into two reservoirs, which were called the Black and Caspian Seas. Between the latter and the World Ocean stretch thousands of kilometers of waterless path. 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 drainless basin of Eurasia.

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

The network of rivers and sewage is unevenly distributed along the coast. Few rivers flow into the part of the sea from the north 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 is an important geographical feature of this reservoir.

Volga

This river is one of the largest in Europe. In Russia, it ranks sixth in size. Regarding the catchment area, it is second only to the Siberian rivers flowing into the Caspian Sea, such as the Ob, Lena, Yenisei, Irtysh. For the source, from where the Volga originates, the key is taken near the village of Volgoverkhovye, Tver Region, on the Valdai Upland. Now there is a chapel at the source, which attracts the attention of tourists, for whom it is a pride 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. Her 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 the location of millionaire cities - Nizhny Novgorod, Samara, Kazan, Volgograd.

Volga Delta

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

It lies 28 m lower than the 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 "the capital of the province of Astrakhan." During his reign, the main attraction of the city, the Assumption Cathedral, was built. Its Kremlin is made of white stone, brought from the capital of the Golden Horde, the city of Saray. 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.

Currently, the Volga needs protection. For this purpose, a reserve has been established at the place where the river flows into the sea. The delta of the Volga, the largest river flowing into the Caspian Sea, abounds in 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 Reserve.

Sulak River

It is located in Dagestan, flows through its territory. It feeds on the waters of melted snows that flow down from the mountains, as well as tributaries: Small 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: Didoyskaya and Tushinskaya. The length of the Sulak River is 144 km. Her pool has enough large area- 15,200 square meters. It flows through the canyon with the same name as the river, then through the Akhetlinsky gorge and finally comes to the plane. Going around the Agrakhan Bay from the south side, Sulak flows into the sea.

The river provides drinking water for Kaspiysk and Makhachkala, and is home to hydroelectric power stations, the urban-type settlements of Sulak and Dubki, and the small town of Kizilyurt.

Samur

The river got its name not by chance. The name translated from the Caucasian language (one of them) means "middle". Indeed, the border between the states of Russia and Azerbaijan is marked along the waterway along the Samur River.

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

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

Samur: the valley and its description

The valley of this river in Dagestan is the most densely populated region. Derbent is located near the mouth - ancient city peace. The banks of the Samur River are home to twenty or more species of relict representatives of the flora. Endemic, endangered and rare species listed in the Red Book grow here.

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

Terek

The river got its name from the Karachay-Balkar peoples who lived along its banks. They called it "Terk Suu", which means "rushing water" in translation. 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 a slope Caucasian ridge. It is 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. At the confluence with the Caspian, the Terek is divided into many branches, as a result of which a vast delta is formed, its area is 4000 square meters. In some places it is very swampy.

The course in this place has changed several times. The old arms have now been turned 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 channels.

How is the Terek replenished?

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

The river is not distinguished by cleanliness and transparency. The turbidity of the water is large: 400-500 g/m 3 . Every year, the Terek and its tributaries pollute the Caspian Sea, pouring into it from 9 to 26 million tons of various suspensions. This is due to the rocks of which the shores are composed, and they are clayey.

Terek mouth

The Sunzha is the largest tributary flowing into the Terek, the lower reaches of which are measured precisely from this river. By this time, the Terek flows for a long time over the flat terrain, leaving the mountains located behind the Elkhot Gates. The bottom here is composed 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 channel here is elevated above the valley, in appearance it resembles a canal, which is fenced with a high embankment. The water level rises above the land level. This phenomenon is due to a natural cause. Since the Terek is a stormy river, it brings sand and stones from the Caucasian ridge to in large numbers. Given that the current in the lower reaches is weak, some of them settle here and do not reach the sea. For the inhabitants of the area, sediments are both a threat and a boon. 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 into the Russian style by the decree of Catherine II in 1775. Just at this time, the Peasant War was suppressed, the leader of which was Pugachev. The name is still preserved in the Bashkir language, and in Kazakhstan it is official. The Urals are the third longest in Europe, only the Volga and the Danube are larger than this river.

The Ural originates in Russia, on the slope of the Kruglyaya Sopka 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 meeting a plateau on the way, it makes a sharp turn and continues to flow in a north-westerly direction. However, beyond Orenburg, its direction again changes to the southwestern, which is considered the main one. Having overcome the winding path, the Ural flows into the Caspian Sea. The length of the river is 2428 km. The mouth is divided into branches and tends to shallow.

The Ural is a river along which the natural water boundary between Europe and Asia passes, with the exception of the upper reaches. This is an internal European river, but its upper reaches to the east of the Ural Range are the territory of Asia.

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 needs, agricultural and industrial needs. Hydroelectric power plants are being built on the rivers, the energy of which is in demand by man for various purposes. River basins are full of fish, algae, shellfish. Even in ancient times, people chose river valleys for future settlements. And now cities and towns are being built on their banks. Rivers ply passenger and transport ships, performing important tasks for the transport of passengers and goods.

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42° N sh. 51° E d. HGI AMOL

Caspian Sea- the largest enclosed body of water on Earth, which can be classified as the largest drainless lake, or as a full-fledged sea, due to its size, and also due to the fact that its bed is composed of an oceanic type of earth's crust. Located at the crossroads of Europe and Asia. The water in the Caspian is brackish, - 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.

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Subtitles

Etymology

Geographical position

The Caspian Sea is located at the crossroads of Europe and Asia. The length of the 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 ° in d.).

According to the physical and geographical conditions, the Caspian Sea is conditionally divided into three parts - the North Caspian (25% of the sea area), the Middle Caspian (36%) and the South Caspian (39%). The conditional border between the North and Middle Caspian runs along the line Chechen Island - Cape Tyub-Karagan, between the Middle and South Caspian - along the line Chilov Island - Cape Gan-Gulu.

Coast

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

peninsulas

• Absheron peninsula, located on the western coast of the Caspian in the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, the cities of Baku and Sumgayit are located on its territory
• Mangyshlak, located on the east coast of the Caspian Sea, on the territory of Kazakhstan, on its territory is the city of Aktau

Islands

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

gulfs

• Dead Kultuk (former Komsomolets, former Tsesarevich Bay)
• Kenderly
• Turkmenbashi  (bay) (former Krasnovodsk)
• Turkmen (bay)
• Gyzylagach (former bay named after Kirov)
• Astrakhan (bay)
• Gyzlar
• Hyrcanus (former Astarabad)
• Anzali (former Pahlavi)

Kara-Bogaz-Gol

At east coast is salt Lake Kara-Bogaz-Gol, which until 1980 was a bay-lagoon of the Caspian Sea, connected to it by a narrow strait. In 1980, a dam was built separating Kara-Bogaz-Gol from the Caspian Sea, in 1984 a culvert was built, after which the level of Kara-Bogaz-Gol dropped by several meters. In 1992, the strait was restored, through which water leaves the Caspian Sea to Kara-Bogaz-Gol and evaporates there. Every year, 8-10 cubic kilometers of water (according to other sources - 25 cubic kilometers) and about 15 million tons of salt enter Kara-Bogaz-Gol from the Caspian Sea.

Rivers flowing into the Caspian Sea

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

Caspian Sea Basin

coastal states

According to the Intergovernmental Economic Conference of the Caspian States:

The Caspian Sea washes the shores of five coastal states:

Cities on the coast of the Caspian Sea

On the Russian coast there are cities - Lagan, Makhachkala, Kaspiysk, Izberbash, Dagestan Lights and the most Southern City Russian Derbent. port city The Caspian Sea is also considered Astrakhan, which, however, is not located on the shores of the Caspian Sea, but in the Volga delta, 60 kilometers from the northern coast of 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 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. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, char and others, of flowering - zoster and ruppia. By origin, the flora refers mainly to the Neogene age, however, some plants were brought into the Caspian Sea by man consciously, or on the bottoms of ships.

History of the Caspian Sea

Origin of the Caspian Sea

The Caspian Sea is of oceanic origin - its bed is composed of an oceanic type of earth's crust. 13 million liters n. the formed Alps separated the Sarmatian Sea from the Mediterranean. 3.4 - 1.8 million liters. n. (Pliocene) there was the Akchagyl Sea, the deposits of which were studied by N. I. Andrusov. It was originally formed on the site of the dried up Pontic Sea, from which Lake Balakhani remained (on the territory of the southern Caspian). The Akchagyl Sea evolves into the Apsheron Sea, which covers the Caspian Sea and floods the territories of Turkmenistan and the Lower Volga region.

In the early Neopleistocene, after the Turkyan regression (-150 to -200 m), corresponding to the magnetic inversion of Matuyama-Brunhes, there were isolated Early Baku and Late Baku (level up to 20 m) basins with a runoff (about 400 thousand years ago). In the middle Neopleistocene, there were basins: Urundzhik (up to -15 m), early Khazar early (200 thousand years ago), early Khazar middle (level up to 35-40 m) and early Khazar late. In the late Pleistocene, there was an isolated late Khazar basin (level up to -10 m, 100 thousand years ago), which, after a slight regression, was replaced by the Hyrcanian basin. After the Atelier regression (-120 - -140 m), approx. 17 thousand liters n. the early Khvalynian transgression began - up to + 50 m (the Manych-Kerch Strait functioned), which was interrupted by the Elton regression. The Early Khvalynsky II basin (level up to 50 m) was replaced by the Enotaevskaya regression (from -45 to -110 m). OK. 13.4-13.1 thousand liters. n. the late Khvalynian transgression (0 m) began, which was replaced in the Holocene (about 9-7 thousand years ago) by the Mangyshlak regression (from -50 to -90 m). The Novo-Caspian basin was brackish (11-13‰), warm-water and isolated (level up to -19 m).

Anthropological and cultural history of the Caspian Sea

Shipping

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

Fishing and seafood

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

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and therapeutic mud in the coastal zone creates good conditions for rest and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the 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 coast of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. Azerbaijan is actively developing resort area in the Baku region. At the moment, a world-class resort has been created in Amburan, another modern tourist complex is being built near the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also being developed in Nabran, in the north of Azerbaijan. However, high prices, a generally low level of service and the lack of advertising lead to the fact that there are almost no foreign tourists in the Caspian resorts. The development of the tourism industry in Turkmenistan is hampered by a long policy of isolation, in Iran - by Sharia law, due to which the mass vacation of foreign tourists on the Caspian coast of Iran is impossible.

Environmental problems

Environmental problems The Caspian Sea is 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 vital activity of coastal cities, as well as the flooding of individual facilities due to the rise in the level of the Caspian Sea. Predatory harvesting of sturgeons and their caviar, rampant poaching lead to a decrease in the number of sturgeons and forced restrictions on their production and export.

Legal status of the Caspian Sea

After the collapse of the USSR, the division of the Caspian Sea has long been and still remains the subject of unsettled disagreements related to the division of the resources of the Caspian shelf - oil and gas, as well as biological resources. For a long time there were negotiations 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 - on dividing the Caspian along one fifth between all the Caspian states.

With regard to the Caspian Sea, the key is the physical and geographical circumstance that it is a closed inland water body 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 1982 UN Convention on the Law of the Sea, should not automatically apply to the Caspian Sea. Based on this, it would be unlawful to apply such concepts as “territorial sea”, “exclusive economic zone”, “continental shelf”, etc. to the Caspian Sea.

Caspian Sea

The Caspian Sea is the largest lake on Earth, located at the junction of Europe and Asia, called the sea because of its size. The Caspian Sea is an endorheic lake, and the water in it is salty, from 0.05% near the mouth of the Volga to 11-13% in the southeast. The water level is subject to fluctuations, at present - about 28 m below the level of the World Ocean. The area of ​​the Caspian Sea is currently approximately 371,000 sq. km, the maximum depth is 1025 m.

The length of the coastline of the Caspian Sea is estimated at about 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 coastline it is indented by water channels and islands of the Volga and Ural deltas, the shores are low and swampy, and the water surface is covered with thickets in many places. The east coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding coasts are on the west coast in the area of ​​the Apsheron Peninsula and on the east coast in the area of ​​the Kazakh Gulf and Kara-Bogaz-Gol.

130 rivers flow into the Caspian Sea, of which 9 rivers have a mouth in the form of a delta. Large rivers flowing into the Caspian Sea are the Volga, Terek (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Samur (Russian border with Azerbaijan), Atrek (Turkmenistan) and others.

The Caspian Sea washes the shores of five coastal states:

Russia (Dagestan, Kalmykia and Astrakhan region) - in the west and northwest, the length of the coastline is 695 kilometers Kazakhstan - in the north, northeast and east, the length of the coastline is 2320 kilometers Turkmenistan - in the southeast, the length of the coastline is 1200 kilometers Iran - in the south, the length of the coastline - 724 kilometers of Azerbaijan - in the southwest, the length of the coastline is 955 kilometers

Water temperature

It is subject to significant latitudinal changes, most pronounced 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. The average water temperature at west coast 1 - 2 °C higher than that of the eastern, and in the open sea the water temperature is 2 - 4 °C higher than that of the coasts.

The climate of the Caspian Sea is continental in the northern part, temperate in the middle part and subtropical in the southern part. In winter, the average monthly temperature of the Caspian varies from -8 -10 in the northern part to +8 - +10 in the southern part, in summer period- from +24 - +25 in the northern part to +26 - +27 in the southern part. The maximum temperature recorded on the east coast is 44 degrees.

Animal world

The fauna of the Caspian is represented by 1809 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian Sea, and most of the world's stocks of sturgeon are concentrated in it, as well as such freshwater fish as vobla, carp, pike perch. The Caspian Sea is the habitat of such fish as carp, mullet, sprat, kutum, bream, salmon, perch, pike. The Caspian Sea is also inhabited by a marine mammal - the Caspian seal.

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, char and others, of flowering - zoster and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were brought into the Caspian Sea by man either consciously or on the bottoms of ships.

Oil and gas

Many oil and gas fields are being developed in the Caspian Sea. The proven oil resources in the Caspian Sea are about 10 billion tons, the total resources of oil and gas condensate 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. In the second half of the 19th century, oil production began on an industrial scale on the Absheron Peninsula, and then on other territories.

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.

The Caspian Sea is inland and is located in a vast continental depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows it to be called a lake, but it has all the features of the sea, since it had connections with the ocean in past geological epochs.

The area of ​​the sea is 386.4 thousand km2, the volume of water is 78 thousand m3.

The Caspian Sea has a vast drainage basin, with an area of ​​about 3.5 million km2. The nature of landscapes, climatic conditions and types of rivers are different. Despite its vastness, only 62.6% of its area is in waste areas; about 26.1% - for drainless. The area of ​​the Caspian Sea itself is 11.3%. 130 rivers flow into it, but almost all of them are located in the north and west (and the eastern coast does not have a single river reaching the sea at all). The largest river in the Caspian basin is the Volga, which provides 78% of the river water entering the sea (it should be noted that more than 25% of the Russian economy is located in the basin of this river, and this undoubtedly determines many other features of the waters of the Caspian Sea), as well as the Kura River , Zhaiyk (Ural), Terek, Sulak, Samur.

In physical and geographical terms and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional boundary between the northern and middle parts runs along the line of Chechen Island–Cape Tyub-Karagan, between the middle and southern parts - along the line of Zhiloy Island–Cape Kuuli.

The shelf of the Caspian Sea, on average, is limited to depths of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at about 500–600 m, in the southern part, where it is very steep, at 700–750 m.

The northern part of the sea is shallow, its average depth is 5–6 m, the maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom relief is complicated by the presence of banks, islands, furrows.

The middle part of the sea is a separate basin, an area maximum depths which - the Derbent depression - is shifted to the western coast. The average depth of this part of the sea is 190 m, the greatest is 788 m.

The southern part of the sea is separated from the middle part by the Apsheron threshold, which is a continuation of the Greater Caucasus. Depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian basin with a maximum sea depth of 1025 m is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.

The shores of the Caspian Sea are diverse. In the northern part of the sea, they are quite strongly indented. Here are the bays of Kizlyar, Agrakhan, Mangyshlak and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy, Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islets and channels, which often change their position. Many small islands and banks are located on other parts of the coastline.

The middle part of the sea has a relatively flat coastline. On the western coast, on the border with the southern part of the sea, the Apsheron Peninsula is located. To the east of it, the islands and banks of the Apsheron archipelago stand out, of which the most large island Residential. The eastern shore of the Middle Caspian is more indented, the Kazakh Bay stands out here with the Kenderli Bay and several capes. The largest bay of this coast is Kara-Bogaz-Gol.

South of the Absheron Peninsula are the islands of the Baku archipelago. The origin of these islands, as well as some banks off the eastern coast of the southern part of the sea, is associated with the activity of underwater mud volcanoes lying at the bottom of the sea. On east coast the large bays of Turkmenbashi and Turkmensky are located, and near it is the island of Ogurchinsky.

One of the most striking phenomena of the Caspian Sea is the periodic variability of its level. In historical times, the Caspian Sea had a lower level than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) of the sea level, the amplitude of its fluctuations has been almost 4 m, from -25.3 m in the eighties of the XIX century. to -29 m in 1977. In the last century, the level of the Caspian Sea has changed significantly twice. In 1929 it stood at a mark of about -26 m, and since it had been close to this mark for almost a century, this position of the level was considered as a long-term or secular average. In 1930, the level began to decline rapidly. Already by 1941, it had dropped by almost 2 m. This led to the drying up of vast coastal areas of the bottom. The decrease in the level, with its small fluctuations (short-term insignificant rises in the level in 1946-1948 and 1956-1958), continued until 1977 and reached the mark of -29.02 m, i.e., the level took the lowest position for last 200 years.

In 1978, contrary to all forecasts, the sea level began to rise. As of 1994, the level of the Caspian Sea was at -26.5 m, that is, in 16 years the level has risen by more than 2 m. The rate of this rise is 15 cm per year. The level increment in some years was higher, and in 1991 it reached 39 cm.

The general fluctuations in the level of the Caspian Sea are superimposed by its seasonal changes, the average long-term of which reaches 40 cm, as well as surge phenomena. The latter are especially pronounced in the Northern Caspian. The northwestern coast is characterized by large surges created by the prevailing, especially in the cold season, storms of eastern and southeastern directions. Over the past decades, a number of large (more than 1.5–3 m) surges have been observed here. A particularly large surge with catastrophic consequences was noted in 1952. Fluctuations in the level of the Caspian Sea cause great damage to the states surrounding its water area.

Climate. The Caspian Sea is located in the temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since the sea stretches for almost 1200 km from north to south.

In the Caspian region, various circulation systems interact, however, easterly winds prevail throughout the year (the influence of the Asian high). The position at rather low latitudes provides a positive balance of heat inflow, so the Caspian Sea serves as a source of heat and moisture for passing air masses for most of the year. The average annual temperature in the northern part of the sea is 8–10°С, in the middle part - 11–14°С, in the southern part – 15–17°С. However, in the northernmost parts of the sea, the average January temperature is from –7 to –10°C, and the minimum temperature during arctic air intrusions is up to –30°C, which determines the formation of the ice cover. In summer, rather high temperatures dominate over the entire region under consideration - 24–26°C. Thus, the Northern Caspian is subject to the most sharp temperature fluctuations.

The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, and most of it falls on the cold season of the year (from October to March). However, the Northern Caspian differs in this respect from the rest of the basin: here the average annual precipitation is less (only 137 mm for the western part), and the distribution over the seasons is more even (10–18 mm per month). In general, we can talk about proximity climatic conditions to the arid ones.

Water temperature. The distinctive features of the Caspian Sea (great differences in depths in different parts of the sea, the nature of the bottom relief, isolation) have a certain influence on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be considered as homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and South Caspian, surface and deep masses separated by a transitional layer can be distinguished. In the Northern Caspian and in the surface layers of the Middle and Southern Caspian, the water temperature varies over a wide range. In winter, temperatures vary from north to south from less than 2 to 10°С, the water temperature near the western coast is 1–2°С higher than near the eastern one, in the open sea the temperature is higher than near the coasts: by 2–3°С in the middle part and by 3–4°С in the southern part of the sea. In winter, the temperature distribution is more uniform with depth, which is facilitated by the winter vertical circulation. In moderate and harsh winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing.

In summer, the temperature varies in space from 20 to 28°C. The highest temperatures are observed in the southern part of the sea; temperatures are also quite high in the well-warmed shallow North Caspian. The zone of distribution of the lowest temperatures is adjacent to the east coast. This is due to the rise of cold deep waters to the surface. Temperatures are also relatively low in the poorly heated deep-water central part. In the open areas of the sea, in late May–early June, the formation of a temperature jump layer begins, which is most clearly expressed in August. Most often it is located between 20 and 30 m in the middle part of the sea and 30 and 40 m in the south. In the middle part of the sea, due to the surge near the eastern coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature during the year is about 4.5°C in the middle part and 5.8–5.9°C in the south.

Salinity. Salinity values ​​are determined by such factors as river runoff, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts of the Northern Caspian and between the Northern and Middle Caspian, the bottom topography, which determines the location of waters with different salinity, mainly along the isobaths, evaporation, which ensures the shortage of fresh water and the inflow of more saline ones. These factors collectively affect the seasonal differences in salinity.

The Northern Caspian can be considered as a reservoir of constant mixing of river and Caspian waters. The most active mixing occurs in the western part, where both river and Central Caspian waters directly enter. In this case, horizontal salinity gradients can reach 1‰ per 1 km.

The eastern part of the Northern Caspian is characterized by a more uniform salinity field, since most of the river and sea (Middle Caspian) waters enter this area of ​​the sea in a transformed form.

According to the values ​​of horizontal salinity gradients, in the western part of the Northern Caspian, a river-sea contact zone can be distinguished with water salinity from 2 to 10‰, in the eastern part from 2 to 6‰.

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea waters, with runoff playing a decisive role. The intensification of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated waters coming from the coast in summer is 10–15°C higher than that of the bottom ones.

In the deep basins of the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of ​​the Apsheron threshold, where it is 1.6‰ in the surface layer and 2.1‰ at the 5 m horizon.

The decrease in salinity along the western coast of the South Caspian in the 0–20 m layer is caused by the runoff of the Kura River. The influence of the Kura runoff decreases with depth; at the horizons of 40–70 m, the range of salinity fluctuations is no more than 1.1‰. Along the entire western coast to the Absheron Peninsula stretches a strip of desalinated water with a salinity of 10–12.5‰ coming from the Northern Caspian.

In addition, salinity increases in the South Caspian due to the removal of saline waters from bays and inlets on the eastern shelf under the action of southeasterly winds. In the future, these waters are transferred to the Middle Caspian.

In the deep layers of the Middle and South Caspian, salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep part of the South Caspian, the upper boundary of waters with increased salinity drops to 250 m. Obviously, vertical mixing of waters is difficult in these parts of the sea.

Surface water circulation. Currents in the sea are mainly wind-driven. In the western part of the Northern Caspian, currents of the western and eastern quarters are most often observed, in the eastern - southwestern and southern. The currents caused by the runoff of the Volga and Ural rivers can be traced only within the estuarine coast. The prevailing current velocities are 10–15 cm/s, in the open areas of the Northern Caspian maximum speeds about 30 cm/s.

In the coastal areas of the middle and southern parts of the sea, in accordance with the wind directions, currents of the northwestern, northern, southeastern and southern directions, currents often occur off the east coast east direction. Along the western coast of the middle part of the sea, the most stable currents are southeast and south. Current velocities are on average about 20–40 cm/s, the maximum ones reach 50–80 cm/s. Other types of currents also play a significant role in the circulation of sea waters: gradient, seiche, inertial ones.

ice formation. The Northern Caspian is covered with ice annually in November, the area of ​​the freezing part of the water area depends on the severity of the winter: in severe winters, the entire Northern Caspian is covered with ice, in soft ice it stays within the 2–3 meter isobath. The appearance of ice in the middle and southern parts sea ​​falls on December-January. Near the eastern coast, ice is of local origin, near the western coast - most often brought from the northern part of the sea. In severe winters, shallow bays freeze off the eastern coast of the middle part of the sea, coasts and landfast ice form off the coast, and drift ice spreads to the Absheron Peninsula in abnormally cold winters off the western coast. The disappearance of the ice cover is observed in the second half of February–March.

Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of regularities.
The central part of the Northern Caspian is characterized by a fairly uniform distribution of oxygen. An increased oxygen content is found in the areas of the pre-estuary seashore of the Volga River, a lower one - in the southwestern part of the Northern Caspian.

In the Middle and South Caspian, the highest oxygen concentrations are confined to coastal shallow areas and pre-estuary seashores of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.).

In the deep-water regions of the Caspian Sea, the main pattern is preserved in all seasons - a decrease in oxygen concentration with depth.
Due to the autumn-winter cooling, the density of the waters of the North Caspian increases to a value at which it becomes possible for the flow of North Caspian waters with a high oxygen content along the continental slope to significant depths of the Caspian Sea.

The seasonal distribution of oxygen is mainly related to the annual course and seasonal ratio of production-destruction processes occurring in the sea.

In spring, the production of oxygen in the process of photosynthesis quite significantly covers the decrease in oxygen due to a decrease in its solubility with an increase in water temperature in spring.

In the areas of the estuarine coasts of the rivers feeding the Caspian Sea, in spring there is a sharp increase in the relative oxygen content, which in turn is an integral indicator of the intensification of the photosynthesis process and characterizes the degree of productivity of the mixing zones of sea and river waters.

In summer, due to significant warming of water masses and activation of photosynthesis processes, the leading factors in the formation of the oxygen regime in surface waters are photosynthetic processes, in near-bottom waters - biochemical oxygen consumption by bottom sediments.

Due to the high temperature of the waters, the stratification of the water column, the large influx of organic matter and its intense oxidation, oxygen is quickly consumed with its minimal entry into the lower layers of the sea, as a result of which an oxygen deficiency zone is formed in the Northern Caspian. Intensive photosynthesis in the open waters of the deep-water regions of the Middle and South Caspian covers the upper 25-meter layer, where oxygen saturation is more than 120%.

In autumn, in the well-aerated shallow water areas of the Northern, Middle and Southern Caspian, the formation of oxygen fields is determined by the processes of water cooling and the less active, but still ongoing process of photosynthesis. The oxygen content is rising.

The spatial distribution of nutrients in the Caspian Sea reveals the following patterns:

• increased concentrations of biogenic substances characterize areas of pre-estuary coastlines of rivers that feed the sea and shallow areas of the sea subject to active anthropogenic influence(Baku Bay, Turkmenbashi Bay, water areas adjacent to Makhachkala, Fort Shevchenko, etc.);
• The Northern Caspian, which is a vast mixing zone of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
• in the Middle Caspian, the cyclonic nature of the circulation contributes to the upwelling of deep waters with a high content of nutrients into the overlying layers of the sea;
• in the deep water areas of the Middle and South Caspian, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.

The dynamics of nutrient concentrations during the year in the Caspian Sea is influenced by such factors as seasonal fluctuations in the biogenic runoff into the sea, the seasonal ratio of production-destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter time in the Northern Caspian, the processes of winter vertical circulation in the deep sea areas.

In winter, a significant area of ​​the Northern Caspian is covered with ice, but biochemical processes are actively developing in the under-ice water and ice. The ice of the Northern Caspian, being a kind of accumulator of biogenic substances, transforms these substances entering the sea from and from the atmosphere.

As a result of the winter vertical circulation of waters in the deep-sea regions of the Middle and Southern Caspian in the cold season, the active layer of the sea is enriched with nutrients due to their supply from the underlying layers.

Spring for the waters of the North Caspian is characterized by a minimum content of phosphates, nitrites and silicon, which is explained by the spring outbreak of phytoplankton development (silicon is actively consumed by diatoms). High concentrations of ammonium and nitrate nitrogen, characteristic of the waters of a large area of ​​the Northern Caspian during floods, are due to intensive flushing by river waters.

In the spring season, in the area of ​​water exchange between the Northern and Middle Caspian in the subsurface layer, with the maximum oxygen content, the content of phosphates is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.

In the South Caspian, the distribution of nutrients in spring is basically similar to their distribution in the Middle Caspian.

In the summertime, the waters of the Northern Caspian reveal a redistribution of various forms of biogenic compounds. Here, the content of ammonium nitrogen and nitrates significantly decreases, while at the same time there is a slight increase in the concentrations of phosphates and nitrites and a rather significant increase in the concentration of silicon. In the Middle and South Caspian, the concentration of phosphates has decreased due to their consumption in the process of photosynthesis and the difficulty of water exchange with the deep water accumulation zone.

In autumn, in the Caspian Sea, due to the cessation of the activity of some types of phytoplankton, the content of phosphates and nitrates increases, and the concentration of silicon decreases, as an autumn outbreak of diatoms occurs.

Oil has been produced on the shelf of the Caspian Sea for more than 150 years.

Currently, large reserves of hydrocarbons are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons of oil equivalent (of which 132 million tons of oil and 78 billion m3 of gas), on the shelf of the Northern Caspian - 1 billion tons of oil .

In total, about 2 billion tons of oil have already been produced in the Caspian.

Losses of oil and products of its processing during extraction, transportation and use reach 2% of the total volume.

The main sources of pollutants, including oil products, entering the Caspian Sea are carry-over with river runoff, discharge of untreated industrial and agricultural effluents, domestic wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, transportation of oil by sea. 90% of pollutants with river runoff are concentrated in the Northern Caspian, industrial effluents are confined mainly to the area of ​​the Apsheron Peninsula, and increased oil pollution of the Southern Caspian is associated with oil production and oil exploration drilling, as well as active volcanic activity(mud) in the zone of oil and gas bearing structures.

From the territory of Russia, about 55 thousand tons of oil products enter the Northern Caspian every year, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.

The thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange and threatens the death of hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg/l, for phytoplankton - 0.1 mg/l.

The development of oil and gas resources of the bottom of the Caspian Sea, the estimated reserves of which are estimated at 12–15 billion tons of standard fuel, will become the main factor in the anthropogenic load on the ecosystem of the sea in the coming decades.

Caspian autochthonous fauna. The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, mollusks, etc.

arctic views. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire fauna of the Caspian (mysids, sea cockroach, white salmon, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna is crustaceans (71.4%), which easily tolerate desalination and live on great depths The Middle and Southern Caspian (from 200 to 700 m), since the lowest water temperatures (4.9–5.9 ° C) are kept here throughout the year.

mediterranean views. These are 2 types of mollusks, needle-fish, etc. At the beginning of the 20s of our century, the mollusk mitilyastra penetrated here, later 2 types of shrimp (with mullets, during their acclimatization), 2 types of mullet and flounder. Some Mediterranean species entered the Caspian after the opening of the Volga-Don Canal. Mediterranean species play a significant role in the fish food base of the Caspian Sea.

Freshwater fauna (228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, cyprinids, as well as rotifers).

sea ​​views. These are ciliates (386 forms), 2 species of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropod molluscs (74 species and subspecies), bivalve mollusks (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most unique brackish water bodies on the planet.

The Caspian Sea provides more than 80% of the world's sturgeon catch, most of which falls on the North Caspian.

To increase the catches of sturgeon, which dropped sharply during the years of sea level drop, a set of measures is being implemented. Among them - a complete ban on sturgeon fishing in the sea and its regulation in rivers, an increase in the scale of factory breeding of sturgeons.

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