What flows into the Caspian Sea. Resources of the Caspian Sea

, Kura

Caspian Sea- the largest closed body of water on Earth, which can be classified as the largest closed lake, or as a full-fledged sea, due to its size, as well as due to the fact that its bed is composed of an oceanic type of crust. Located at the junction 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 was 27.16 m below sea level. The area of ​​the Caspian Sea is currently about 371,000 km², the maximum depth is 1025 m.

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Etymology

Geographical position

The Caspian Sea is located at the junction of Europe and Asia. The length of the sea from north to south is about 1200 kilometers (36 ° 34 "-47 ° 13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46 ° -56 ° E etc.).

According to 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 of Chechen Island - Cape Tyub-Karagan, between the Middle and South Caspian - along the line of Chilov Island - Cape Gan-Gulu.

Coast

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

Peninsula

• Absheron Peninsula, located on the western coast of the Caspian Sea on the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory are the cities of Baku and Sumgait
• Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory there is the city of Aktau

Islands

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

The largest islands:

Gulfs

Large bays:

Kara-Bogaz-Gol

Near the eastern coast is the salt lake Kara-Bogaz-Gol, which until 1980 was a lagoon-bay 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 several meters. In 1992, the strait was restored, along it the water leaves the Caspian Sea to Kara-Bogaz-Gol and evaporates there. Every year from the Caspian Sea, Kara-Bogaz-Gol receives 8-10 cubic kilometers of water (according to other sources - 25 cubic kilometers) and about 15 million tons of salt.

Rivers flowing into the Caspian Sea

130 rivers flow into the Caspian Sea, 9 of which have delta-shaped estuaries. Large rivers flowing into the Caspian Sea are 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 into the Caspian Sea.

Basin of the Caspian Sea

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, Dagestanskie Ogni and the southernmost city of 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 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 the fluctuations in the water level. With 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 above its surface. 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 according to the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian 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, charovy and others, from flowering plants - zostera and ruppia. In origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into the Caspian Sea by humans deliberately, or on the bottoms of ships.

History

Origin

The Caspian Sea is of oceanic origin - its bed is composed of oceanic crust. 13 million liters. n. the formed Alps separated the Sarmatian Sea from the Mediterranean. 3.4 - 1.8 million liters. n. (Pliocene) the Akchagyl Sea existed, the deposits of which were investigated by N.I. Andrusov. Originally formed on the site of the dried-up Pontic Sea, from which Lake Balakhany remained (on the territory of the southern Caspian Sea). The Akchagyl transgression was replaced by the Domashka regression (a drop of 20 - 40 m from the level of the Akchagyl basin), accompanied by strong desalination of sea waters, which is due to the termination of the supply of sea (oceanic) waters from the outside. After a short Domashkin regression at the beginning of the Quaternary period (Eopleistocene), the Caspian is almost restored in the form of the Absheron Sea, which covers the Caspian and floods the territories of Turkmenistan and the Lower Volga region. At the beginning of the Absheron transgression, the basin turns into a brackish water body. The Absheron Sea exists from 1.7 to 1 million years ago. The beginning of the Pleistocene in the Caspian Sea was marked by a long and deep Türkyan regression (-150 m to -200 m), corresponding to the Matuyama-Brunhes magnetic inversion (0.8 million years ago). The water mass of the Türkyan basin with an area of ​​208 thousand km² was concentrated in the South Caspian and part of the Middle Caspian basins, between which there was a shallow strait in the area of ​​the Apsheron threshold. In the Early Neopleistocene, after the Türkyan regression, there existed an isolated Early Bakinsky basin and a late Bakinsky (level up to 20 m) drainage basin (about 400 ka BP). The Venedian (Mishovdag) regression divided the Baku and Urundzhik (Middle Neopleistocene, up to −15 m) transgressions at the end of the Early - beginning of the Late Pleistocene (basin area - 336 thousand km²). A large deep Cheleken regression (up to −20 m), corresponding to the optimum of the Likhvin interglacial (350-300 thousand years ago), was noted between the marine Urundzhik and Khazar deposits. In the Middle Neopleistocene, there were basins: the Early Khazar Early (200 thousand years ago), the Early Khazar Middle (level up to 35-40 m), and the Early Khazar Late. In the Late Neopleistocene, there was an isolated Late Khazar basin (level up to -10 m, 100 ka), after which a small Cherniyarsk regression of the second half - the end of the Middle Pleistocene (thermoluminescent dates 122-184 ka) occurred, in in turn, replaced by the Girkan (Gyurgyan) basin.

The deep long-term Atelian regression of the mid-late Pleistocene at the initial stage had a level of −20 - −25 m, at the maximum stage −100 - −120 m, at the third stage - −45 - −50 m. At the maximum, the basin area is reduced to 228 thousand km² ... After atelier regression (−120 - −140 m), approx. 17 thousand liters n. the early Khvalynian transgression began - up to + 50 m (the Manych-Kerch Strait was functioning), which was interrupted by the Elton regression. The Early Khvalynian II basin (level up to 50 m) was replaced at the beginning of the Holocene by a short-term Enotai regression (from −45 to −110 m), coinciding in time with the end of the Preboreal and the beginning of the Boreal. Enotaevskaya regression was replaced by late Khvalynian transgression (0 m). The late Khvalynian transgression was replaced in the Holocene (about 9-7 thousand years ago or 7.2-6.4 thousand years ago) by the Mangyshlak regression (from -50 to -90 m). The Mangyshlak regression was replaced in the first phase of interglacial cooling and humidification (Atlantic period) by the Novocaspian transgression. The Novocaspian basin was brackish water (11-13 ‰), warm water and isolated (level up to −19 m). At least three cycles of transgressive-regressive phases in the development of the Novo-Caspian basin have been recorded. The Dagestan (Gousan) transgression previously belonged to the initial stage of the New Caspian epoch, however, the absence of the leading Novocaspian form in its sediments Cerastoderma glaucum (Cardium edule) provides a basis for its separation into an independent transgression of the Caspian. Izberbash regression, separating the Dagestan and the New Caspian transgressions of the Caspian proper, occurred in the interval between 4.3 and 3.9 thousand years ago. Judging by the structure of the Turali section (Dagestan) and the data of radiocarbon analysis, transgressions were recorded twice - about 1900 and 1700 years ago.

Anthropological and cultural history of the Caspian Sea

Shipping

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

Fishing and seafood production

Fishing (sturgeon, bream, carp, pike perch, sprat), caviar and 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 sturgeon and their caviar is flourishing in the Caspian Sea.

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and curative mud in the coastal area creates good conditions for recreation and treatment. At the same time, in terms of the development of resorts and tourism industry, the Caspian coast is noticeably inferior 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. A resort area in the Baku region is actively developing in Azerbaijan. At the moment, a world-class resort has been created in Amburan, another modern tourist complex is being built in the area of ​​the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also developing in Nabran, in the north of Azerbaijan. However, high prices, generally low level of service and 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 hindered by a long-term policy of isolation, in Iran - by Sharia law, which makes it impossible for foreign tourists to spend mass vacations on the Caspian coast of Iran.

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 influx of pollutants from the Volga and other rivers flowing into the Caspian Sea, the life of coastal cities, as well as flooding of certain objects due to the rise in the level of the Caspian Sea. Predatory hunting 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.

Legal status

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 Caspian shelf resources - oil and gas, as well as biological resources. For a long time, negotiations were going on 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 by one fifth between all the Caspian states.

With regard to the Caspian, 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 be automatically applied to the Caspian Sea. Based on this, in relation to the Caspian it would be inappropriate 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 ships flying the flag of non-Caspian states in its waters.

Negotiations on the legal status of the Caspian are ongoing.

Delimitation of sections of the seabed of the Caspian Sea for the purpose of subsoil use

The Russian Federation signed 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 to it dated May 13, 2002), an agreement with Azerbaijan on delimiting adjacent sections 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 delimitation lines of adjacent sections of the seabed of the Caspian Sea (dated May 14, 2003), which established the geographic coordinates of the dividing lines delimiting the sections of the seabed, within which the parties exercise their sovereign rights in the field of exploration and production of mineral resources.

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 and smooth. In the northern part, the coastline is cut by water streams 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 eastern coast is dominated by limestone shores 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 Bay and Kara-Bogaz-Gol.

Peninsulas of the Caspian Sea

Major peninsulas of the Caspian Sea:
* Agrakhan Peninsula
* Absheron Peninsula, located on the western coast of the Caspian Sea in the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory are the cities of Baku and Sumgait
* Buzachi
* Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory there is the city of Aktau.
* Miancale
* Tub-Karagan

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

The largest islands:

* Ashur-Ada
* Garasu
* Gum
* Dash
* Zira (island)
* Zyanbil
* Kur Dasha
* Hara-Zira
* Sengi-Mugan
* Chechnya (island)
* Chygyl

Large bays of the Caspian Sea:

* Agrakhan Gulf,
* Komsomolets (bay),
* Mangyshlak,
* Kazakh (bay),
* Turkmenbashi (bay) (former Krasnovodsk),
* Turkmen (bay),
* Gizilagach,
* Astrakhan (bay)
* Gyzlar
* Hyrcanus (formerly Astarabad) and
* Anzeli (formerly Pahlavi).

Rivers flowing into the Caspian Sea

130 rivers flow into the Caspian Sea, 9 of which have delta-shaped estuaries. 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 largest river flowing into the Caspian Sea is the Volga, its average annual runoff is 215-224 cubic kilometers. The Volga, Ural, Terek and Emba provide up to 88 - 90% of the annual runoff of the Caspian Sea.

Basin of the Caspian Sea

The area of ​​the Caspian Sea basin is approximately 3.1 - 3.5 million square kilometers, which is approximately 10 percent of the world's territory of enclosed water basins. The length of the Caspian Sea basin from north to south is about 2500 kilometers, from west to east - about 1000 kilometers. The Caspian Sea basin covers 9 states - Azerbaijan, Armenia, Georgia, Iran, Kazakhstan, Russia, Uzbekistan, Turkey and Turkmenistan.

Coastal states

The Caspian Sea washes the shores of five coastal states:
* Russia (Dagestan, Kalmykia and the Astrakhan region) - in the west and northwest, the length of the coastline is 695 kilometers
* Kazakhstan - in the north, north-east 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 is 724 kilometers
* Azerbaijan - in the southwest, the length of the coastline is 955 kilometers

Cities on the coast of the Caspian Sea

The largest city - port on the Caspian Sea - Baku, the capital of Azerbaijan, which is located in the southern part of the Absheron Peninsula and employs 2,070 thousand people (2003). Other large Azerbaijani Caspian cities are Sumgait, which is located in the northern part of the Absheron Peninsula, and Lankaran, which is located near the southern border of Azerbaijan. To the South-East of the Absheron Peninsula, there is a village of oil workers Neftyanye Kamni, whose structures are located on artificial islands, overpasses and technological sites.

Large Russian cities - the capital of Dagestan Makhachkala and the southernmost city of Russia Derbent - are located on the western coast of the Caspian Sea. 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 the northern coast of the Caspian Sea.

On the eastern coast of the Caspian Sea is the Kazakh city - the port of Aktau, in the north in the Ural delta, 20 km from the sea, the city of Atyrau is located, south of Kara-Bogaz-Gol on the northern coast of the Krasnovodsk Bay - the Turkmen city of Turkmenbashi, formerly Krasnovodsk. Several Caspian cities are located on the southern (Iranian) coast, the largest of which is Anzali.

Area, depth, volume of water

The area and volume of water in the Caspian Sea varies significantly depending on the fluctuations in the water level. With a water level of -26.75 m, the area was approximately 392,600 square kilometers, the volume of water was 78,648 cubic kilometers, which is approximately 44 percent of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters above its surface. 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 according to the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian 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 3 thousand years, the amplitude of changes in the water level of the Caspian Sea was 15 meters. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuation have been conducted since 1837, during this time the highest water level was recorded in 1882 (-25.2 m), the lowest in 1977 (-29.0 m) , since 1978 the water level has been rising and in 1995 reached the level of -26.7 m, since 1996 there has been a tendency for the level of the Caspian Sea to decrease again. Scientists associate the reasons for the change in the water level of the Caspian Sea with climatic, geological and anthropogenic factors.

Water temperature

The water temperature 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 difference in water temperature is about 10 ° C. For shallow areas with depths less than 25 m, the annual amplitude can reach 25-26 ° C. On average, the water temperature near the western coast is 1–2 ° C higher than that of the east coast, and in the open sea the water temperature is 2–4 ° C higher than that near the coasts. By the nature of the horizontal structure of the temperature field in the annual cycle of variability, three time segment in the upper 2-meter layer. From October to March, the water temperature increases in the southern and eastern, which is especially well traced in the Middle Caspian. Two stable quasi-latitude zones can be distinguished, where temperature gradients are increased. This is, firstly, the border between the North and Middle Caspian, and, secondly, between the Middle and South. At the ice edge, in the northern frontal zone, the temperature in February-March increases from 0 to 5 ° C, in the southern frontal zone, in the area of ​​the Apsheron sill, from 7 to 10 ° C. During this period, the least cooled waters are in the center of the South Caspian, which form a quasi-stationary core.

In April-May, the area of ​​minimum temperatures moves to the Middle Caspian, which is associated with a faster warming up of waters in the shallow northern part of the sea. True, at the beginning of the season in the northern part of the sea, a large amount of heat is spent on ice melting, but already in May the temperature here rises to 16-17 ° C. In the middle part, the temperature at this time is 13-15 ° C, and in the south it increases to 17-18 ° C.

Spring water warming evens out the horizontal gradients, and the temperature difference between the coastal areas and the open sea does not exceed 0.5 ° C. The heating of the surface layer, which begins in March, disturbs the uniformity in the temperature distribution with depth; in June-September, there is a horizontal uniformity in the temperature distribution in the surface layer. In August, which is the month of greatest warming, the water temperature throughout the sea is 24-26 ° C, and in the southern regions it rises to 28 ° C. In August, the water temperature in shallow bays, for example, in Krasnovodsk, can reach 32 ° C. The main feature of the water temperature field at this time is upwelling. It is observed annually along the entire eastern coast of the Middle Caspian and partially penetrates even into the South Caspian.

The rise of cold deep waters occurs with varying intensity as a result of the influence of the northwestern winds prevailing in the summer season. The wind in this direction causes the outflow of warm surface waters from the coast and the rise of colder waters from the intermediate layers. The upwelling begins in June, but it reaches its highest intensity in July-August. As a result, a decrease in temperature is observed on the water surface (7-15 ° C). Horizontal temperature gradients reach 2.3 ° C at the surface and 4.2 ° C at a depth of 20 m.

The upwelling focus is gradually shifting from 41-42 ° north. latitude in June, to 43-45 ° north. latitude in September. Summer upwelling is of great importance for the Caspian Sea, fundamentally changing the dynamic processes in the deep water area. In the open areas of the sea in late May - early June, a layer of temperature jump begins, which is most pronounced in August. Most often, it is located between the horizons of 20 and 30 m in the middle part of the sea and 30 and 40 m in the southern part. Vertical temperature gradients in the jump layer are very significant and can reach several degrees per meter. In the middle part of the sea, as a result of the drive off the eastern coast, the shock layer rises close to the surface.

Since in the Caspian Sea there is no stable baroclinic layer with a large supply of potential energy, similar to the main thermocline of the World Ocean, then with the termination of the prevailing winds causing upwelling, and with the onset of autumn-winter convection in October-November, a rapid restructuring of the temperature fields to the winter regime occurs. In the open sea, the water temperature in the surface layer drops in the middle to 12-13 ° C, in the southern part to 16-17 ° C. In the vertical structure, the shock layer is eroded due to convective mixing and disappears by the end of November.

Water composition

The salt composition of the waters of the enclosed Caspian Sea differs from that of the ocean. There are significant differences in the ratios of the concentrations of salt-forming ions, especially for the waters of areas under the direct influence of 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 the chemical composition of river waters. The most conservative ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ions. In the Caspian, the content of calcium and magnesium cations is almost two times higher than in the Sea of ​​Azov, and the content of sulfate anions is three times higher. The salinity of the water changes especially sharply in the northern part of the sea: from 0.1 units. psu in the mouth areas of the Volga and the Urals up to 10-11 units. psu on the border with the Middle Caspian.

Mineralization in shallow salty bays-kultuk can reach 60-100 g / kg. In the Northern Caspian, during the entire ice-free period from April to November, a salinity front of a quasi-latitude location is observed. The greatest desalination associated with the spread of river runoff over the sea area is observed in June. The formation of the salinity field in the North Caspian is greatly influenced by the wind field. In the middle and southern parts of the sea, salinity fluctuations are small. Basically, it is 11.2-12.8 units. psu, increasing southerly and easterly. Salinity increases insignificantly with depth (by 0.1-0.2 psu units).

In the deep-water part of the Caspian Sea, in the vertical salinity profile, there are characteristic isohaline troughs and local extrema in the area of ​​the eastern continental slope, which indicate the processes of bottom sliding of waters salinizing in the eastern shallow waters of the South Caspian. The salinity value also strongly depends on the sea level and (which is interconnected) on the volume of continental runoff.

Bottom relief

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

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, the average monthly temperature of the Caspian Sea 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 highest temperature recorded on the east coast is 44 degrees.

Average annual rainfall is 200 millimeters per year, from 90-100 millimeters in the arid eastern part to 1,700 millimeters off the southwestern subtropical coast. Evaporation of water from the surface of the Caspian Sea is about 1000 millimeters per year, the most intense evaporation is in the area of ​​the Absheron Peninsula and in the eastern part of the South Caspian - up to 1400 millimeters per year.

Winds often blow on the territory of the Caspian Sea, their average annual speed is 3-7 meters per second, northern winds prevail in the wind rose. In the autumn and winter months, the winds increase, the speed of the winds often reaches 35-40 meters per second. The most windy areas are the Apsheron Peninsula and the vicinity of Makhachkala - Derbent, where the highest wave was recorded - 11 meters.

Currents

The circulation of waters in the Caspian Sea is associated with runoff and winds. Since most of the runoff is in the North Caspian, northern currents prevail. The intense northern current carries water from the North Caspian along the western coast to the Absheron Peninsula, where the current splits into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

Animal world

The fauna of the Caspian Sea is represented by 1809 species, of which 415 are vertebrates. There are 101 species of fish registered in the Caspian world, and most of the world's sturgeon stocks, as well as freshwater fish such as roach, carp, and pike perch, are concentrated in the Caspian world. The Caspian Sea is a habitat for such fish as carp, mullet, sprat, kutum, bream, salmon, perch, pike. The Caspian Sea is also home to a marine mammal - the Caspian seal. Since March 31, 2008, 363 dead seals have been found on the coast of the Caspian Sea in Kazakhstan.

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, charovy and others, and of flowering plants - zostera and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into the Caspian Sea by humans deliberately or on the bottoms of ships.

Origin of the Caspian Sea

The Caspian Sea is of oceanic origin - its bed is composed of oceanic crust. It was formed about 10 million years ago, when the closed Sarmatian Sea, which lost contact with the world's oceans about 70 million years ago, split into two parts - the "Caspian Sea" and the Black Sea.

Anthropological and cultural history of the Caspian Sea

Finds in the Khuto cave off the southern coast of the Caspian Sea indicate that people lived in these parts about 75 thousand years ago. The first mentions of the Caspian Sea and tribes living on its coast are found at Herodotus. Approximately in the V-II centuries. BC NS. the tribes of the Saks lived on the coast of the Caspian. Later, during the period of the settlement of the Turks, during the IV-V centuries. n. NS. Talysh tribes (Talysh) lived here. According to ancient Armenian and Iranian manuscripts, Russians sailed in the Caspian Sea from the 9th - 10th centuries.

Exploration of the Caspian Sea

The exploration of the Caspian Sea was started by Peter the Great, when, on his order, in 1714-1715, an expedition was organized under the leadership of A. Bekovich-Cherkassky. In the 1820s, hydrographic research was continued by I. F. Soyomov, and later by I. V. Tokmachev, M. I. Voinovich and other researchers. At the beginning of the 19th century, instrumental survey of the banks was carried out by I.F.Kolodkin, in the middle of the 19th century. - instrumental geographic 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 has been conducted under the leadership of N.M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power in the Caspian Sea, geological research by I. M. Gubkin and other Soviet geologists was actively carried out, mainly aimed at finding oil, as well as research to study the water balance and fluctuations in the level of the Caspian Sea.

Mining of 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 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. In the second half of the 19th century, oil production began in industrial volumes on the Absheron Peninsula, then in 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.

Shipping

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

Fishing and seafood production

Fishing (sturgeon, bream, carp, pike perch, sprat), caviar and 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 sturgeon and their caviar is flourishing in the Caspian Sea.

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and curative mud in the coastal area creates good conditions for recreation and treatment. At the same time, in terms of the development of resorts and tourism industry, the Caspian coast is noticeably inferior 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.

Ecological problems

The environmental problems of the Caspian Sea are associated with water pollution as a result of oil production and transportation on the continental shelf, the influx of pollutants from the Volga and other rivers flowing into the Caspian Sea, the vital activity of coastal cities, as well as flooding of certain objects due to the rise in the level of the Caspian Sea. Predatory hunting 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.

Frontier dispute over the 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 going on 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 one fifth of each between all the Caspian states. In 2003, Russia, Azerbaijan and Kazakhstan signed an agreement on the partial division of the Caspian Sea along the median line.

Coordinates: 42.622596 50.041848

The Caspian Sea is simultaneously considered both an endless lake and a full-fledged sea. The confusion stems from brackish waters and a marine-like hydrological regime.

The Caspian Sea is located on the border of Asia and Europe. Its area is about 370 thousand km 2, the maximum depth is just over one kilometer. The Caspian Sea is conditionally divided into three almost equal parts: South (39% of the area), Middle (36%) and North (25%).

The sea washes simultaneously the Russian, Kazakh, Azerbaijani, Turkmen and Iranian shores.

Shore of the Caspian Sea(Caspian Sea region) has a length of about 7 thousand kilometers, if you count together with the islands. In the north, the low seashore is covered with swamps and thickets, and has multiple water channels. The eastern and western coasts of the Caspian have a winding shape, in some places the shores are covered with limestone.

There are many islands in the Caspian: Dash-Zira, Kyur Dashi, Dzhambaysky, Boyuk-Zira, Gum, Chigil, Khere-Zira, Zenbil, Ogurchinsky, Tyuleniy, Ashur-Ada, etc. Peninsulas: Mangyshlak, Tyub-Karagan, Apsheronsky and Miankale. Their total area is approximately 400 km 2.

It flows into the Caspian Sea more than a hundred different rivers, the most significant are the Ural, Terek, Volga, Atrek, Emba, Samur. Almost all of them provide the sea with 85–95% of the annual drainage.

The largest bays of the Caspian: Kaidak, Agrakhan, Kazakh, Dead Kultuk, Turkmenbashi, Mangyshlak, Gyzlar, Girkan, Kaidak.

Caspian climate

The Caspian Sea is located in three climatic zones at once: subtropical climate in the south, continental in the north and temperate in the middle. In winter, the average temperature varies from -10 to +10 degrees, while in summer the air warms up to about +25 degrees. During the year, precipitation falls from 110 mm in the east and up to 1500 mm in the west.

The average wind speed is 3‒7 m / s, but in autumn and winter it often increases to 35 m / s. The most drained areas are the coastal areas of Makhachkala, Derbent and the Absheron Peninsula.

Caspian Sea water temperature ranges from zero to +10 degrees in winter, and from 23 to 28 degrees in the summer months. In some coastal shallow waters, the water can warm up to 35-40 degrees.

Only the northern part of the sea is subject to freezing, but in especially cold winters, the coastal zones of the middle part are added to it. The ice cover appears in November and disappears only in March.

Problems of the Caspian Region

Water pollution is one of the main environmental problems in the Caspian. Oil production, various harmful substances from flowing rivers, waste from nearby cities - all this negatively affects the state of sea water. Additional troubles are created by poachers, whose actions reduce the number of fish of certain species found in the Caspian Sea.

Sea level rise is also causing serious financial damage to all Caspian countries.

According to conservative estimates, the restoration of destroyed buildings and the implementation of comprehensive measures to protect the coast from flooding cost tens of millions of dollars.

Cities and resorts on the Caspian Sea

The largest city and port washed by the waters of the Caspian Sea is Baku. Among other settlements of Azerbaijan, located in close proximity to the sea, are Sumgait and Lankaran. On the eastern shores there is the city of Turkmenbashi, and about ten kilometers away by the sea is the large Turkmen resort of Avaza.

On the Russian side, the following cities are located on the sea coast: Makhachkala, Izberbash, Derbent, Lagan and Kaspiysk. Astrakhan is often called a port city, although it is located about 65 kilometers from the northern shores of the Caspian Sea.

Astrakhan

Beach recreation in this region is not provided: along the sea coast there are only continuous reed thickets. However, tourists go to Astrakhan not for idle lying on the beach, but for fishing and various types of outdoor activities: diving, riding on catamarans, jet skis, etc. In July and August, excursion ships run across the Caspian Sea.

Dagestan

For a classic seaside vacation, it is better to go to Makhachkala, Kaspiysk or Izberbash - this is where not only good sandy beaches are located, but also worthy recreation centers. The range of entertainment on the seashore from the Dagestan side is quite wide: swimming, therapeutic mud springs, windsurfing, kiting, rock climbing and paragliding.

The only drawback of this area is the underdeveloped infrastructure.

In addition, there is an opinion among some Russian tourists that Dagestan is far from the most peaceful territory that is part of the North Caucasian Federal District.

Kazakhstan

A much calmer environment can be found in the Kazakh resorts of Kuryk, Atyrau and Aktau. The latter is the most popular tourist city in Kazakhstan: there are many good entertainment facilities and comfortable beaches. In summer, the temperature here is very high, reaching up to +40 degrees in the daytime, and dropping only to +30 at night.

The disadvantages of Kazakhstan as a tourist country are the same poor infrastructure and rudimentary transport links between the regions.

Azerbaijan

The best places for recreation on the Caspian coast are Baku, Nabran, Lankaran and other Azerbaijani resorts. Fortunately, everything is fine with the infrastructure in this country: for example, in the area of ​​the Absheron Peninsula, there are several modern comfortable hotels with swimming pools and beaches.

However, in order to enjoy a vacation on the Caspian Sea in Azerbaijan, you need to spend a lot of money. In addition, it is possible to get to Baku quite quickly only by plane - trains rarely run, and the journey from Russia itself takes two or three days.

Tourists should not forget that Dagestan and Azerbaijan are Islamic countries, so all "unbelievers" need to adjust their usual behavior to local customs.

If you follow the simple rules of stay, nothing will spoil your holiday on the Caspian Sea.

The Caspian Sea is one of the largest salt water bodies on Earth, located at the junction of Europe and Asia. Its total area is about 370 thousand square meters. km. The reservoir receives over 100 water streams. The largest rivers flowing into the Volga, Ural, Emba, Terek, Sulak, Samur, Kura, Atrek, Sefidrud.

Volga river - the pearl of Russia

The Volga is a river flowing in the territory of the Russian Federation, partially crosses Kazakhstan. Belongs to the category of the largest and longest rivers on Earth. The total length of the Volga is over 3,500 km. The river originates in the Volgoverkhovye village of the Tver region, located on After that, it continues its movement through the territory of the Russian Federation.

It flows into the Caspian Sea, but does not have a direct outlet to the World Ocean, therefore it is referred to as internal flows. The watercourse receives about 200 tributaries and has more than 150 thousand drains. Today, reservoirs have been built on the river, which allow regulating the flow, due to which fluctuations in the water level have been sharply reduced.

The fishing of the river is varied. Melon growing prevails in the Volga region: the fields are occupied by grain and industrial crops; table salt is mined. Oil and gas fields have been discovered in the Urals region. The Volga is the largest river flowing into the Caspian Sea, therefore it is of great importance for Russia. The main transport facility that allows you to cross this stream is the longest in Russia.

Ural - a river in Eastern Europe

The Ural, like the Volga River, flows on the territory of two states - Kazakhstan and the Russian Federation. The historical name is Yaik. It originates in Bashkortostan at the top of the Uraltau ridge. The Ural River flows into the Caspian Sea. Its pool is the sixth largest in the Russian Federation, and its area is more than 230 sq. km. An interesting fact: the Ural River, contrary to popular belief, belongs to the inner European river, and only its upper course in Russia belongs to Asia.

The mouth of the watercourse is gradually shallowing. At this point, the river is divided into several branches. This feature is typical for the entire length of the channel. During floods, one can observe how the Ural overflows its banks, in principle, like many other rivers in Russia flowing into the Caspian Sea. This is especially observed in places with a gentle coastline. Flooding occurs at a distance of up to 7 meters from the channel.

Emba - the river of Kazakhstan

Emba is a river flowing in the territory of the Republic of Kazakhstan. The name comes from the Turkmen language, literally translates as "the valley of food". The river basin with an area of ​​40 thousand square meters. km. The river begins its journey in the Mugodzhary mountains and, flowing along, is lost among the marshes. Asking which rivers flow into the Caspian Sea, we can say that in full-flowing years the Emba reaches its basin.

Natural resources such as oil and gas are being extracted along the river's coastline. The issue of passing the border between Europe and Asia along the Emba watercourse, as in the case of the river. Ural, an open topic today. The reason for this is a natural factor: the mountains of the Ural ridge, which are the main reference point for drawing borders, disappear, forming a homogeneous terrain.

Terek - mountain water stream

Terek is a river of the North Caucasus. The name is literally translated from Turkic as "poplar". The Terek flows out of the glacier of Mount Zilga-Khokh, located in the Trusov Gorge of the Caucasus Range. passes through the lands of many states: North Ossetia, Georgia, Stavropol Territory, Kabardino-Balkaria, Dagestan and the Chechen Republic. It flows into the Caspian Sea and the Arkhangelsk Gulf. The length of the river is just over 600 km, the basin is about 43 thousand square meters. km. An interesting fact is that every 60-70 years the stream forms a new transit arm, while the old one loses its strength and disappears.

The Terek, like other rivers flowing into the Caspian Sea, is widely used to meet human economic needs: it is used to irrigate arid areas of adjacent lowlands. Also, there are several hydroelectric power plants on the water stream, the total average annual output of which is more than 200 million kWh. In the near future, it is planned to launch new additional stations.

Sulak - water stream of Dagestan

Sulak is a river that connects the Avar Koisu and the Andean Koisu streams. It flows on the territory of Dagestan. It begins in the Main Sulak Canyon and ends its journey in the waters of the Caspian Sea. The main purpose of the river is water supply to two cities of Dagestan - Makhachkala and Kaspiysk. Also, several hydroelectric power plants are already located on the river, it is planned to launch new ones to increase the generated capacity.

Samur - the pearl of South Dagestan

Samur is the second largest river in Dagestan. Literally the name is translated from Indo-Aryan as "abundance of water". It begins at the foot of Mount Guton; it flows into the waters of the Caspian by two branches - Samur and Maly Samur. The total length of the river is just over 200 km.

All rivers flowing into the Caspian Sea are of great importance for the territories through which they flow. Samur is no exception. The main direction of the use of the river is irrigation of lands and provision of residents of nearby cities with drinking water. It is because of this that the hydroelectric complex and a number of the Samur-Divichinsky canal were built.

At the beginning of the 20th century (2010), Russia and Azerbaijan signed an interstate agreement requiring both sides to efficiently use the resources of the Samur River. The same agreement introduced territorial changes between these countries. The border of the two states was moved to the middle of the hydroelectric complex.

Kura is the largest river in Transcaucasia

Asking which rivers flow into the Caspian Sea, I would like to describe the Kura stream. It flows on the ground of three states at once: Turkey, Georgia, Azerbaijan. The length of the stream is more than 1000 km, the total area of ​​the basin is about 200 thousand square meters. km. Part of the basin is located on the territory of Armenia and Iran. The source of the river is in the Turkish province of Kars, and flows into the waters of the Caspian Sea. The path of the river is thorny, laid among hollows and gorges, for which it got its name, which in translation from the Mingrelian language means "gnaw", that is, the Kura is a river, "gnawing" itself even among the mountains.

There are many cities on it, such as Borjomi, Tbilisi, Mtskheta and others. It plays an important role in meeting the economic needs of the inhabitants of these cities: hydroelectric power plants are located, and the Mingechevir reservoir created on the river is one of the main reserves of fresh water for Azerbaijan. Unfortunately, the ecological state of the stream leaves much to be desired: the level of harmful substances is several times higher than the permissible limits.

Features of the Atrek River

Atrek is a river located in Iran and Turkmenistan. It originates in the Turkmen-Kharasan mountains. Due to the active use in economic needs for irrigating land, the river became shallow. For this reason, it reaches the Caspian Sea only during the flood period.

Sefidrud - a high-water river of the Caspian

Sefidrud is a large river of the Iranian state. Initially it was formed by the confluence of two water streams - Kyzyluzen and Shahrud. Now it flows out of the Shabanau reservoir and flows into the depths of the Caspian. The total length of the river is over 700 km. The creation of a reservoir has become a necessity. It made it possible to minimize the risks of flooding, thereby protecting the cities located in the river delta. Water is used for irrigation of lands with a total area of ​​more than 200 thousand hectares of land.

As can be seen from the presented material, the Earth's water resources are in an unsatisfactory state. The rivers flowing into the Caspian Sea are actively used by man to satisfy his needs. And this has a detrimental effect on their condition: the watercourses are depleted and polluted. That is why scientists from all over the world are sounding the alarm and conducting active propaganda, calling for saving and conserving water on Earth.

Caspian Sea is inland and is located in an extensive mainland depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows us to call it a lake, but it has all the features of the sea, since in past geological eras it had connections with the ocean.
Today Russia has access only to the North Caspian and the Dagestan part of the western coast of the Middle Caspian. The waters of the Caspian Sea wash the shores of countries such as Azerbaijan, Iran, Turkmenistan, Kazakhstan.
The sea area 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 the landscapes, climatic conditions and types of rivers are different. Despite the vastness of the drainage basin, only 62.6% of its area is in wastewater areas; about 26.1% - for closed drainage. 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 bank 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 waters entering the sea (it should be noted that more than 25% of Russia's economy is located in the basin of this river, and this undoubtedly determines many hydrochemical and other features of the Caspian Sea waters), as well as rivers Kura, Zhaiyk (Ural), Terek, Sulak, Samur.

Physically and geographically and by the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional border between the northern and middle parts runs along the line of the Chechen island - the Tyub-Karagan cape, between the middle and the south - along the line of the Zhiloy island - Kuuli cape.
The shelf of the Caspian Sea is, on average, limited to a depth of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at a depth of 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, 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, grooves.
The middle part of the sea is a separate basin, the area of ​​maximum depths of 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 Apsheron sill, which is a continuation of the Greater Caucasus. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum depth of 1025 m for the sea is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.

The shores The Caspian Sea is diverse. In the northern part of the sea, they are quite indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea - 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 Absheron Peninsula is located. To the east of it, the islands and banks of the Absheron archipelago stand out, of which the largest is Zhiloy Island. The eastern coast of the Middle Caspian is more indented, here the Kazakh Gulf with Kenderli Bay and several capes stand out. The largest bay on this coast is Kara-Bogaz-Gol.

The islands of the Baku archipelago are located to the south of the Absheron Peninsula. 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 on the bottom of the sea. On the eastern coast there are large bays of Turkmenbashy and Turkmensky, and near the island of Ogurchinsky.

One of the most striking phenomena of the Caspian is the periodic variability of its level. In historical time, the Caspian Sea had a level lower 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) over the sea level, the amplitude of its fluctuations was 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 changed significantly twice. In 1929, it stood at about –26 m, and since it had been close to this mark for almost a century, this level position was considered as mean annual or secular. In 1930, the level began to decline rapidly. By 1941, it had dropped by almost 2 m. This led to the drying up of vast coastal bottom areas. 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 -29.02 m, that is, the level took the lowest position in the 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 rose by more than 2 m. The rate of this rise is 15 cm per year. The increase in the level in some years was higher, and in 1991 it reached 39 cm.

The general fluctuations in the level of the Caspian Sea are superimposed on its seasonal changes, the mean multiyear of which reaches 40 cm, as well as on surges. The latter are especially pronounced in the Northern Caspian. The northwestern coast is characterized by large surges created by the prevailing storms of the eastern and southeastern directions, especially during the cold period of the year. A number of large (more than 1.5–3 m) surges have been observed here over the past decades. An especially 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 temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since from north to south the sea stretches for almost 1200 km.
In the Caspian region, various systems of atmospheric circulation interact, however, during the year, the winds of the eastern points prevail (the influence of the Asian maximum). The position in rather low latitudes provides a positive balance of heat inflow, therefore the Caspian Sea serves as a source of heat and moisture for the passing air masses for most of the year. The average annual air temperature in the northern part of the sea is 8–10 ° С, in the middle - 11–14 ° С, in the southern part - 15–17 ° С. However, in the northernmost regions of the sea, the average January temperature is from –7 to –10 ° С, and the minimum during the invasions of the Arctic air is up to –30 ° С, which determines the formation of the ice cover. In summer, the entire region under consideration is dominated by rather high temperatures - 24–26 ° С. Thus, the North Caspian is subject to the sharpest temperature fluctuations.

The Caspian Sea is characterized by a very small amount of precipitation falling per year - only 180 mm, and most of it falls on the cold season of the year (from October to March). However, the North Caspian Sea differs in this respect from the rest of the basin: here the average annual precipitation is less (for the western part, only 137 mm), and the distribution over the seasons is more even (10–18 mm per month). In general, we can talk about the proximity of climatic conditions to arid ones.
Water temperature. Distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, the nature of the bottom topography, isolation) have a certain impact on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be regarded 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 can be distinguished, separated by a transitional layer. In the North Caspian and in the surface layers of the Middle and South Caspian, the water temperature varies over a wide range. In winter, temperatures change from north to south from less than 2 to 10 ° С, the water temperature near the western coast is 1–2 ° С higher than that of the east, in the open sea the temperature is higher than at 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. During moderate and severe winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing point.

In summer, the temperature changes 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 eastern coast. This is due to the rise to the surface of cold deep waters. Temperatures are also relatively low in the poorly warmed deep-water central part. In the open areas of the sea, in late May – early June, a layer of temperature jump begins, which is most pronounced in August. Most often, it is located between the horizons of 20 and 30 m in the middle part of the sea and 30 and 40 m in the southern part. In the middle part of the sea, due to the drive off the east coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature throughout the year is about 4.5 ° C in the middle and 5.8–5.9 ° C in the southern part.

Salinity. Salinity values ​​are determined by such factors as river runoff, water dynamics, which mainly includes wind and gradient currents, the resulting water exchange between the western and eastern parts of the North Caspian and between the North and Middle Caspian, bottom topography, which determines the location of waters with different salinity, mainly along the isobaths, evaporation, providing a shortage of fresh water and the inflow of more saline ones. These factors collectively affect seasonal differences in salinity.
The North 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 Middle Caspian waters directly flow. In this case, the horizontal salinity gradients can reach 1 ‰ per 1 km.

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

According to the values ​​of the horizontal salinity gradients, it is possible to distinguish in the western part of the North Caspian a river-sea contact zone 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 water arriving in summer from the seaside is 10–15 ° C higher than that of the bottom water.
In the deep-water 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 Apsheron sill area, 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 Kura river runoff. 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, there is a strip of desalinated waters with a salinity of 10–12.5 ‰ coming from the North Caspian.

In addition, in the South Caspian, an increase in salinity occurs when saline waters are carried out from bays and bays on the eastern shelf under the influence of southeastern winds. Subsequently, 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-water part of the South Caspian, the upper boundary of waters with increased salinity drops to 250 m. It is obvious that in these parts of the sea, vertical mixing of waters is difficult.

Surface water circulation. The currents in the sea are mainly wind-driven. In the western part of the Northern Caspian, the currents of the western and eastern quarters are most often observed, in the eastern part, the southwestern and southern ones. The currents caused by the runoff of the Volga and Ural rivers are traced only within the estuarine seashore. The prevailing velocities of currents are 10–15 cm / s, in the open regions of the Northern Caspian the maximum velocities are 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 north-west, north, south-east and south directions are observed, along the east coast currents of the east direction often take place. Along the western coast of the middle part of the sea, the most stable currents are southeastern and southern. The velocities of the currents 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.

Ice formation. The North Caspian is covered with ice annually in November, the area of ​​the freezing part of the water area depends on the severity of winter: in severe winters, the entire North Caspian is covered with ice, in soft ice it is kept within the 2-3 meter isobath. The appearance of ice in the middle and southern parts of the sea occurs in December-January. On the east coast, ice is of local origin, on the west coast - most often brought from the northern part of the sea. In severe winters near the eastern coast of the middle part of the sea, shallow bays freeze, near the coast, coastlines and fast ice form, near the western coast, drifting ice in abnormally cold winters extends to the Absheron Peninsula. The disappearance of the ice cover is observed in the second half of February – March.

On the dynamics of concentrations nutrients During the year, the Caspian Sea is influenced by such factors as seasonal fluctuations of biogenic runoff in the sea, seasonal ratio of production and destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter in the North Caspian, processes of winter vertical circulation in deep-water areas seas.
In winter, a significant water area of ​​the North Caspian is covered with ice, but biochemical processes are actively developing in sub-ice water and in ice. The ice of the North Caspian, being a kind of accumulator of nutrients, transforms these substances entering the sea with river runoff and from the atmosphere.

As a result of the winter vertical circulation of waters in the deep-water regions of the Middle and South 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 Northern 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). The high concentrations of ammonium and nitrate nitrogen, characteristic of the waters of a significant water area of ​​the North Caspian during floods, are due to intensive washing by the river waters of the Volga delta.

In the spring season, in the area of ​​water exchange between the North and Middle Caspian in the subsurface layer, at the maximum oxygen content, the phosphate content 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, redistribution of various forms of biogenic compounds is found in the waters of the Northern Caspian. Here, the content of ammonium nitrogen and nitrates significantly decreases, at the same time there is a slight increase in the concentration of phosphates and nitrites and a rather significant increase in the concentration of silicon. In the Middle and South Caspian, the concentration of phosphates 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 phytoplankton species, the content of phosphates and nitrates increases, while the concentration of silicon decreases, as there is an autumn outbreak of the development of diatoms.

More than 150 years on the shelf of the Caspian Sea oil.
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 cubic meters of gas), on the shelf of the North Caspian - 1 billion tons of oil ...
A total of about 2 billion tons of oil have already been produced in the Caspian Sea.
Losses of oil and products of its processing during extraction, transportation and use reach 2% of the total volume.
Main sources of income pollutants, including oil products, into the Caspian Sea - this is the outflow with river runoff, the discharge of untreated industrial and agricultural wastewater, municipal 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. Places of entry of pollutants with river runoff are 90% concentrated in the North Caspian, industrial effluents are mainly confined to the area of ​​the Absheron Peninsula, and increased oil pollution of the South Caspian is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud volcanism) in the zone of oil and gas structures.

From the territory of Russia, about 55 thousand tons of oil products are annually supplied to the North Caspian, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.
Thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange, threatens the death of the 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 predicted reserves of which are estimated at 12-15 billion tons of standard fuel, in the coming decades will become the main factor of anthropogenic pressure on the ecosystem of the sea.

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

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

Mediterranean views. These are 2 types of mollusks, needle-fish, etc. At the beginning of the 20s of our century, the mithielastr mollusk penetrated here, later 2 types of shrimp (with mullets, upon acclimatization), 2 types of mullets and flounder. Some Mediterranean species entered the Caspian after the opening of the Volga-Don Canal. Mediterranean species play an essential role in the food supply for fish in the Caspian Sea.

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

Marine species. These are ciliates (386 forms), 2 types of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalve molluscs (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most original brackish water bodies of the planet.

The Caspian Sea provides over 80% of the world's sturgeon catches, the bulk of which is in the North Caspian.
To increase catches of sturgeon, which sharply decreased during the years of falling sea level, a set of measures is being carried out. Among them is a complete ban on fishing for sturgeon in the sea and its regulation in rivers, an increase in the scale of factory sturgeon breeding.