Caspian Sea: report. Caspian Sea (lake): rest, photo and map, coasts and countries where the Caspian Sea is located

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, the coastline is indented 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. On the east coast limestone coasts adjoining semi-deserts and deserts predominate. 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.

Peninsulas of the Caspian Sea

Large 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, the cities of Baku and Sumgayit are located on its territory
* Buzachi
* Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory is the city of Aktau.
* Miankale
* Tub-Karagan

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

Most major islands:

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

Large bays of the Caspian Sea:

* Agrakhan Bay,
* Komsomolets (bay),
* Mangyshlak,
* Kazakh (bay),
* Turkmenbashi (Gulf) (former Krasnovodsk),
* Turkmen (bay),
* Gyzylagach,
* Astrakhan (Bay)
* Gyzlar
* Hyrcanus (former Astarabad) and
* Anzali (former Pahlavi).

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. 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 drainage of the Caspian Sea.

Caspian Sea Basin

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 closed water basins. The length of the Caspian Sea basin from north to south is about 2,500 kilometers, from west to east - about 1,000 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 Astrakhan region) - in the west and northwest, length coastline 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, coastline length - 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 - a port on the Caspian Sea - Baku, the capital of Azerbaijan, which is located in the southern part of the Absheron Peninsula and has 2,070 thousand people (2003). Other large Azerbaijani Caspian cities are Sumgayit, 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 the settlement of oil workers Neftyanye Kamni, whose facilities are located on artificial islands, overpasses and technological sites.

Large Russian cities- the capital of Dagestan Makhachkala and the most Southern City Russia's Derbent - 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 east coast The Kazakh city - the port of Aktau is located on the Caspian Sea, in the north in the delta of the Urals, 20 km from the sea, the city of Atyrau is located, south of Kara-Bogaz-Gol on the northern shore of the Krasnovodsk Bay - the Turkmen city of Turkmenbashi, formerly Krasnovodsk. Several Caspian cities are located on the southern (Iranian) coast, the largest of them is Anzali.

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 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 from its surface level. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated from the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

The water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past 3 thousand years, the amplitude of changes in the water level of the Caspian Sea has amounted to 15 meters. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out 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 it reached -26.7 m, since 1996 there has again been a downward trend in the level of the Caspian Sea. Scientists associate the causes of changes in the water level of the Caspian Sea with climatic, geological and anthropogenic factors.

Water temperature

In April-May, the area of minimum temperatures moves to the Middle Caspian, which is associated with faster warming 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 melting ice, but already in May the temperature rises here to 16-17 °C. In the middle part, the temperature at this time is 13-15 °C, and in the south it rises to 17-18 °C.

The spring warming of the water evens out horizontal gradients, and the temperature difference between coastal areas and open sea does not exceed 0.5 °C. The heating of the surface layer, which begins in March, breaks the uniformity in the temperature distribution with depth. In June-September, horizontal uniformity is observed in the temperature distribution in the surface layer. In August, which is the month of the 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 northwestern winds prevailing in the summer season. Wind this direction causes the outflow of warm surface waters from the coast and the rise of colder waters from the intermediate layers. Upwelling starts in June, but it reaches its highest intensity in July-August. As a result, a decrease in temperature (7-15 °C) is observed on the surface of the water. Horizontal temperature gradients reach 2.3 °C at the surface and 4.2 °C at a depth of 20 m.

The center of upwelling is gradually shifting from 41-42° N. latitude in June, to 43-45 ° north. latitude in September. Summer upwelling is of great importance for the Caspian Sea, radically changing the dynamic processes in the deep water area. open areas 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 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 shock layer are very significant and can reach several degrees per meter. In the middle part of the sea, due to the surge near the eastern coast, the shock layer rises close to the surface.

Since there is no stable baroclinic layer in the Caspian Sea with a large potential energy reserve similar to the main thermocline of the World Ocean, with the cessation of the effect of the prevailing winds that cause upwelling, and with the onset of autumn-winter convection in October-November, the temperature fields are rapidly reorganized to the winter regime. In the open sea, the water temperature in the surface layer drops in the middle part to 12-13 °C, in the southern part to 16-17 °C. In the vertical structure, the shock layer is washed out due to convective mixing and disappears by the end of November.

Water composition

Mineralization in shallow saline bays-kultuks can reach 60-100 g/kg. In the Northern Caspian, during the entire ice-free period from April to November, a quasi-latitudinal salinity front 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 Northern 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 in the southern and eastern directions. Salinity increases insignificantly with depth (by 0.1–0.2 psu).

In the deep-water part of the Caspian Sea, in the vertical salinity profile, characteristic isohaline troughs and local extrema are observed in the area of the eastern continental slope, which indicate the processes of near-bottom creep of waters becoming saline in the eastern shallow waters of the South Caspian. The salinity value also strongly depends on sea level and (which is interrelated) on the amount of continental runoff.

Bottom relief

The relief of the northern part of the Caspian is a shallow wavy plain with banks and accumulative islands, the average depth of the Northern Caspian is about 4-8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle. The Middle Caspian is quite deep, the depth of water in the Derbent depression reaches 788 meters. The Apsheron threshold separates the Middle and South Caspian. The South Caspian is considered 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, and in some areas there is an outcrop of bedrock.

Climate

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

The average annual rainfall is 200 millimeters per year, ranging from 90-100 millimeters in the arid eastern part to 1,700 millimeters off the southwestern subtropical coast. The evaporation of water from the surface of the Caspian Sea is about 1000 millimeters per year, the most intense evaporation in the area of the Absheron Peninsula and in the eastern part of the South Caspian is 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, the wind rose is dominated by northern winds. In the autumn and winter months, the winds intensify, the wind speed often reaches 35-40 meters per second. The most windy territories are the Apsheron Peninsula and the environs of Makhachkala - Derbent, where the highest wave was recorded - 11 meters.

currents

The circulation of water in the Caspian Sea is connected with the runoff and winds. Since most of the water flow falls on the Northern Caspian, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current splits into two branches, one of which moves further along West Bank, the other goes to the Eastern Caspian.

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 world, 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. A marine mammal, the Caspian seal, also lives in the Caspian Sea. 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, 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 consciously or on the bottoms of ships.

Origin of the Caspian Sea

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

Anthropological and cultural history of the Caspian Sea

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

Exploration of the Caspian Sea

The exploration of the Caspian Sea was started by Peter the Great, when, on his orders, an expedition was organized in 1714-1715 under the leadership of A. Bekovich-Cherkassky. In the 1820s, hydrographic studies were 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 surveying of the coast was carried out by I.F. Kolodkin, in the middle of the 19th century. - instrumental geographic survey under the guidance of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary research on the hydrology and hydrobiology of the Caspian Sea has been carried out 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 on the study of the water balance and fluctuations in the level of the Caspian Sea.

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.

Shipping

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

Fishing and seafood

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 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 relaxation and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast is noticeably losing Black Sea coast 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 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 objects 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.

Border dispute over the 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 part 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

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

coastline length Caspian Sea estimated at about 6500 - 6700 kilometers, with the islands - up to 7000 kilometers. coast Caspian Sea in most of its territory - low-lying and smooth. In the northern part, the coastline 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.

AT Caspian Sea 130 rivers flow into it, 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.

Map of the Caspian Sea

The Caspian Sea washes the shores of five coastal states:

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 water temperature difference is about 10 °C. For shallow water areas with depths less than 25 m, the annual amplitude can reach 25 - 26 °C. On average, the water temperature near the western coast is 1 - 2 °C higher than that of the eastern coast, and in the open sea the water temperature is 2 - 4 °C higher than near the coasts.

Climate of the Caspian Sea- 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 - 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. AT Caspian Sea 101 species of fish have been registered, and most of the world's sturgeon stocks are concentrated in it, as well as such freshwater fish as roach, carp, pike perch. Caspian Sea- habitat for fish such as carp, mullet, sprat, kutum, bream, salmon, perch, pike. AT Caspian Sea also inhabited by a marine mammal - the Caspian seal.

Vegetable world

Vegetable world Caspian Sea and its coast is represented by 728 species. From plants to Caspian Sea algae predominate - blue-green, diatoms, red, brown, char and others, from flowering ones - zoster and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were brought into Caspian Sea by a person consciously or on the bottoms of ships.

Oil and gas

AT Caspian Sea many oil and gas fields are being developed. Proven oil resources in 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 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, on the coast Caspian Sea and the Caspian shelf, salt, limestone, stone, sand, and clay are also being mined.

Ecological problems

Ecological problems Caspian Sea associated with water pollution as a result of the extraction and transportation of oil on the continental shelf, the flow of pollutants from the Volga and other rivers flowing into Caspian Sea, the vital activity of coastal cities, as well as the flooding of individual facilities due to an increase in the level 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.

CASPIAN SEA (Caspian), the world's largest enclosed body of water, drainless brackish lake. Located on the southern border of Asia and Europe, it washes the shores of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. Because of the size, originality natural conditions and complexity of hydrological processes The Caspian Sea is usually referred to the class of closed inland seas.

The Caspian Sea is located in a vast area of internal flow and occupies a deep tectonic depression. The water level in the sea is at around 27 m below the level of the World Ocean, the area is about 390 thousand km 2, the volume is about 78 thousand km 3. The greatest depth is 1025 m. With a width of 200 to 400 km, the sea is elongated along the meridian for 1030 km.

The largest bays: in the east - Mangyshlak, Kara-Bogaz-Gol, Turkmenbashi (Krasnovodsk), Turkmen; in the west - Kizlyar, Agrakhan, Kyzylagadzh, Baku Bay; in the south - shallow lagoons. There are many islands in the Caspian Sea, but almost all of them are small, with a total area of less than 2 thousand km 2. In the northern part, there are numerous small islands adjacent to the Volga delta; larger ones - Kulaly, Morskoy, Tyuleniy, Chechen. Off the western shores is the Apsheron archipelago, to the south lie the islands of the Baku archipelago, off the eastern coast is the narrow island of Ogurchinsky, elongated from north to south.

The northern shores of the Caspian Sea are low-lying and very sloping, characterized by a wide development of droughts formed as a result of surge phenomena; deltaic shores are also developed here (the deltas of the Volga, the Urals, and the Terek) with an abundant supply of terrigenous material; the Volga delta stands out with extensive reed beds. The western shores are abrasion, to the south of the Absheron Peninsula, mostly accumulative deltaic type with numerous bays and spits. The southern shores are low. The eastern shores are mostly deserted and low-lying, composed of sands.

Relief and geological structure of the bottom.

The Caspian Sea is located in a zone of increased seismic activity. In the city of Krasnovodsk (now Turkmenbashi) in 1895 there was a strong earthquake measuring 8.2 on the Richter scale. Eruptions of mud volcanoes are often observed on the islands and the coast of the southern part of the sea, leading to the formation of new shoals, banks and small islands, which are washed away by waves and reappear.

According to the peculiarities of physical and geographical conditions and the nature of the bottom topography in the Caspian Sea, it is customary to distinguish the Northern, Middle and Southern Caspian. The Northern Caspian is characterized by exceptional shallow water, located completely within the shelf with average depths of 4-5 m. Even small changes in the level here at low coasts lead to significant fluctuations in the area of the water table, so the boundaries of the sea in the northeastern part on small-scale maps are shown by a dotted line. The greatest depths (about 20 m) are observed only near the conditional border with the Middle Caspian, which is drawn along the line connecting Chechen Island (to the north of the Agrakhan Peninsula) with Cape Tyub-Karagan on the Mangyshlak Peninsula. In the relief of the bottom of the Middle Caspian, the Derbent depression stands out (the greatest depth is 788 m). The boundary between the Middle and South Caspian passes over the Apsheron threshold with depths up to 180 m along the line from Chilov Island (to the east of the Absheron Peninsula) to Cape Kuuli (Turkmenistan). The basin of the South Caspian is the most extensive area of the sea with the greatest depths, almost 2/3 of the waters of the Caspian Sea are concentrated here, 1/3 falls on the Middle Caspian, in the North Caspian, due to shallow depths, there is less than 1% of the Caspian waters. In general, the shelf areas (the entire northern part and a wide strip along the eastern coast of the sea) predominate in the bottom relief of the Caspian Sea. The continental slope is most pronounced on the western slope of the Derbent Basin and almost along the entire perimeter of the South Caspian Basin. On the shelf, terrigenous-shell sands, shells, and oolitic sands are common; deep-water areas of the bottom are covered with silty and silty sediments with a high content of calcium carbonate. In some areas of the bottom, Neogene bedrocks are exposed. Mirabilite accumulates in the Ka-ra-Bogaz-Gol Bay.

In tectonic terms, within the Northern Caspian, the southern part of the Caspian syneclise of the East European platform is distinguished, which is framed in the south by the Astrakhan-Aktobe zone, composed of Devonian-Lower Permian carbonate rocks, lying on a volcanic base and containing large deposits of oil and natural combustible gas. Paleozoic folded formations of the Donets-Caspian zone (or the Karpinsky ridge) are pushed onto the syneclise from the southwest, which is a protrusion of the basement of the young Scythian (in the west) and Turan (in the east) platforms, which are separated at the bottom of the Caspian Sea by the Agrakhan-Guryev fault (left shift) of northeast strike. The Middle Caspian mainly belongs to the Turan platform, and its southwestern margin (including the Derbent depression) is a continuation of the Terek-Caspian foredeep of the Greater Caucasus fold system. The sedimentary cover of the platform and trough, composed of Jurassic and younger sediments, contains oil and combustible gas deposits in local uplifts. The Apsheron Sill, which separates the Middle Caspian from the South, is a connecting link of the Cenozoic folded systems of the Greater Caucasus and the Kopetdag. The South Caspian Basin of the Caspian Sea with crust of oceanic or transitional type is filled with a thick (over 25 km) complex of Cenozoic sediments. Numerous large hydrocarbon deposits are concentrated in the South Caspian Basin.

Until the end of the Miocene, the Caspian Sea was a marginal sea of the ancient Tethys Ocean (since the Oligocene, the relic oceanic basin of the Paratethys). By the beginning of the Pliocene, it lost contact with the Black Sea. The Northern and Middle Caspians were drained, and the paleo-Volga valley stretched through them, the delta of which was located in the area of the Apsheron Peninsula. Delta sediments have become the main reservoir of oil and natural combustible gas deposits in Azerbaijan and Turkmenistan. In the late Pliocene, due to the Akchagyl transgression, the area of the Caspian Sea greatly increased and the connection with the World Ocean temporarily resumed. The waters of the sea covered not only the bottom of the modern depression of the Caspian Sea, but also the adjacent territories. In the Quaternary, transgressions (Absheron, Baku, Khazar, Khvalyn) alternated with regressions. The southern half of the Caspian Sea is located in a zone of increased seismic activity.

Climate. The Caspian Sea, strongly elongated from north to south, is located within several climatic zones. In the northern part the climate is temperate continental, on the western coast - temperate warm, southwestern and south coast lie within the subtropics, on the east coast dominated by a desert climate. In winter, over the North and Middle Caspian, the weather is formed under the influence of the Arctic continental and sea air, and the South Caspian is often under the influence of southern cyclones. The weather in the west is unstable rainy, in the east it is dry. In summer, the western and northwestern regions are influenced by the spurs of the Azores atmospheric maximum, and the southeastern regions are influenced by the Iran-Afghan minimum, which together creates dry, stable warm weather. Winds from the north and northwest (up to 40%) and southeast (about 35%) directions prevail over the sea. The average wind speed is about 6 m/s, in central regions sea up to 7 m/s, in the area of the Apsheron Peninsula - 8-9 m/s. Northern storm "Baku Nords" reach speeds of 20-25 m/s. The lowest average monthly air temperatures of -10°С are observed in January-February in the northeastern regions (in the most severe winters they reach -30°С), in the southern regions 8-12°С. In July - August, the average monthly temperatures over the entire sea area are 25-26 °С, with a maximum of up to 44 °С on the east coast. The distribution of atmospheric precipitation is very uneven - from 100 mm per year on the eastern shores to 1700 mm in Lankaran. In the open sea, on average, about 200 mm of precipitation falls annually.

hydrological regime. Changes in the water balance of an enclosed sea strongly affect the change in the volume of water and the corresponding level fluctuations. Average long-term components of the water balance of the Caspian Sea for the 1900-90s (km 3 / cm layer): river runoff 300/77, precipitation 77/20, underground runoff 4/1, evaporation 377/97, runoff in Kara-Bogaz- Goal 13/3, which forms a negative water balance of 9 km 3 or 3 cm layer per year. According to paleogeographic data, over the past 2000 years, the range of fluctuations in the level of the Caspian Sea has reached at least 7 m. -29 m (the lowest position in the last 500 years). The sea surface area has decreased by more than 40 thousand km 2, which exceeds the area Sea of Azov. Since 1978, a rapid rise in level began, and by 1996 a mark of about -27 m relative to the level of the World Ocean was reached. In the modern era, fluctuations in the level of the Caspian Sea are determined mainly by fluctuations in climatic characteristics. Seasonal fluctuations in the level of the Caspian Sea are associated with the uneven flow of river flow (primarily the flow of the Volga), so the lowest level is observed in winter, the highest in summer. Short-term sharp level changes are associated with surge phenomena, they are most pronounced in shallow northern regions and can reach 3-4 m during storm surges. Such surges cause flooding of significant coastal land areas. In the Middle and Southern Caspian, surge fluctuations in the level are on average 10-30 cm, under storm conditions - up to 1.5 m. The frequency of surges, depending on the area, is from one to 5 times a month, the duration is up to one day. In the Caspian, as in any closed reservoir, seiche fluctuations in the level are observed in the form of standing waves with periods of 4-9 hours (wind) and 12 hours (tidal). The magnitude of seiche fluctuations usually does not exceed 20–30 cm.

River flow in the Caspian Sea is distributed extremely unevenly. More than 130 rivers flow into the sea, which, on average, bring about 290 km 3 of fresh water per year. Up to 85% of the river flow falls on the Volga with the Urals and enters the shallow Northern Caspian. The rivers of the western coast - Kura, Samur, Sulak, Terek, etc. - give up to 10% of the runoff. About 5% more fresh water are brought to the South Caspian by the rivers of the Iranian coast. The eastern desert shores are completely devoid of constant fresh water.

The average speed of wind currents is 15-20 cm/s, the highest - up to 70 cm/s. In the North Caspian, the prevailing winds create a flow directed along the northwestern coast to the southwest. In the Middle Caspian, this current merges with the western branch of the local cyclonic circulation and continues to move along the western coast. At the Absheron Peninsula, the current bifurcates. Its part in the open sea flows into the cyclonic circulation of the Middle Caspian, and the coastal part goes around the shores of the South Caspian and turns to the north, joining the coastal current, enveloping the entire eastern coast. The average state of the movement of the Caspian surface waters is often disturbed due to the variability of wind conditions and other factors. Thus, in the northeastern shallow area, a local anticyclonic gyre can occur. Two anticyclonic eddies are often observed in the South Caspian. In the Middle Caspian, during the warm season, steady northwest winds create southward transport along the east coast. In light winds and during calm weather, the currents may have other directions.

Wind waves develop very strongly, since the prevailing winds have a large acceleration length. The excitement develops mainly in the northwestern and southeastern directions. Severe storms are observed in the open waters of the Middle Caspian, in the areas of the city of Makhachkala, the Apsheron Peninsula and the Mangyshlak Peninsula. The average wave height of the greatest frequency is 1-1.5 m, at wind speeds of more than 15 m/s it increases to 2-3 m. 10 m

The water temperature on the sea surface in January - February in the North Caspian is close to freezing (about -0.2 - -0.3 °C) and gradually rises southward to 11 °C off the coast of Iran. In summer, surface waters warm up to 23-28 °С everywhere, except for the eastern shelf of the Middle Caspian, where seasonal coastal upwelling develops in July-August and the water temperature on the surface drops to 12-17 °С. In winter, due to intense convective mixing, the water temperature changes little with depth. In summer, under the upper heated layer at the horizons of 20-30 m, a seasonal thermocline (a layer of sharp temperature change) is formed, separating deep cold waters from warm surface waters. In the bottom layers of water deep sea trenches all year round the temperature remains 4.5-5.5 °C in the Middle Caspian and 5.8-6.5 °C in the South. The salinity in the Caspian Sea is almost 3 times lower than in the open areas of the World Ocean, and averages 12.8-12.9‰. It should be especially emphasized that the salt composition of the Caspian water is not completely identical to the composition of ocean waters, which is explained by the isolation of the sea from the ocean. The waters of the Caspian Sea are poorer in sodium salts and chlorides, but richer in calcium and magnesium carbonates and sulfates due to the unique composition of salts entering the sea with river and underground runoff. The highest salinity variability is observed in the Northern Caspian, where in the estuarine sections of the Volga and the Urals the water is fresh (less than 1‰), and as you move south, the salt content increases to 10-11‰ at the border with the Middle Caspian. The greatest horizontal salinity gradients are characteristic of the frontal zone between sea and river waters. Differences in salinity between the Middle and South Caspian are small, salinity slightly increases from northwest to southeast, reaching 13.6‰ in the Turkmen Gulf (up to 300‰ in Kara-Bogaz-Gol). Salinity changes along the vertical are small and rarely exceed 0.3‰, which indicates good vertical mixing of waters. Water transparency varies over a wide range from 0.2 m in the mouth areas of large rivers to 15-17 m in the central regions of the sea.

According to the ice regime, the Caspian Sea belongs to partially freezing seas. Ice conditions are observed annually only in the northern regions. The Northern Caspian is completely covered with sea ice, the Middle - partially (only in severe winters). Middle border sea ice passes along an arc, turned by a bulge to the north, from the Agrakhan Peninsula in the west to the Tyub-Karagan Peninsula in the east. Usually, ice formation begins in mid-November in the extreme northeast and gradually spreads to the southwest. In January, the entire Northern Caspian is covered with ice, mostly landfast ice (fixed). Drifting ice borders the fast ice with a strip 20-30 km wide. The average thickness of ice is from 30 cm at the southern border to 60 cm in the northeastern regions of the Northern Caspian, in hummocky heaps - up to 1.5 m. The destruction of the ice cover begins in the 2nd half of February. In severe winters, drifting ice is carried to the south, along the western coast, sometimes as far as the Absheron Peninsula. In early April, the sea is completely free of ice cover.

Research History. It is believed that the modern name of the Caspian Sea comes from the ancient tribes of the Caspians, who inhabited the coastal regions in the 1st millennium BC; other historical names: Hyrkan (Irkan), Persian, Khazar, Khvalyn (Khvalis), Khorezm, Derbent. The first mention of the existence of the Caspian Sea dates back to the 5th century BC. Herodotus was one of the first to argue that this reservoir is isolated, that is, it is a lake. In the works of Arab scientists of the Middle Ages, there is information that in the 13-16 centuries the Amu Darya partially flowed into this sea by one of the branches. The well-known numerous ancient Greek, Arabic, European, including Russian, maps of the Caspian Sea until the beginning of the 18th century did not reflect reality and were in fact arbitrary drawings. By order of Tsar Peter I, an expedition was organized in 1714-15 under the leadership of A. Bekovich-Cherkassky, who explored the Caspian Sea, in particular its eastern shores. The first map, on which the contours of the coasts are close to modern ones, was compiled in 1720 using astronomical definitions by Russian military hydrographers F. I. Soymonov and K. Verden. In 1731, Soimonov published the first atlas, and soon the first printed sailing direction of the Caspian Sea. A new edition of the maps of the Caspian Sea with corrections and additions was carried out by Admiral A. I. Nagaev in 1760. The first information on the geology and biology of the Caspian Sea was published by S. G. Gmelin and P. S. Pallas. Hydrographic research in the 2nd half of the 18th century was continued by I.V. Tokmachev, M.I. Voinovich, at the beginning of the 19th century - by A.E. Kolodkin, who was the first to perform instrumental compass survey of the coast. Published in 1807 new map of the Caspian Sea, compiled taking into account the latest inventories. In 1837, systematic instrumental observations of sea level fluctuations began in Baku. In 1847 the first Full description Gulf of Kara-Bogaz-Gol. In 1878, the General Map of the Caspian Sea was published, which reflected the results of the latest astronomical observations, hydrographic surveys, and depth measurements. In 1866, 1904, 1912–13, and 1914–15, under the leadership of N. M. Knipovich, expeditionary studies were carried out in the hydrology and hydrobiology of the Caspian Sea; in 1934, a Commission for the Comprehensive Study of the Caspian Sea was established under the Academy of Sciences of the USSR. A great contribution to the study of the geological structure and oil content of the Apsheron Peninsula and the geological history of the Caspian Sea was made by Soviet geologists I. M. Gubkin, D. V. and V. D. Golubyatnikovs, P. A. Pravoslavlev, V. P. Baturin, S. A . Kovalevsky; in the study of water balance and sea level fluctuations - B. A. Appolov, V. V. Valedinsky, K. P. Voskresensky, L.S. Berg. After the Great Patriotic War, systematic diversified studies were launched in the Caspian Sea, aimed at studying the hydrometeorological regime, biological conditions and the geological structure of the sea.

In the 21st century, two large scientific centers are engaged in solving the problems of the Caspian Sea in Russia. Caspian Marine Research Center (KaspMNIC), established in 1995 by a government decree Russian Federation, conducts research work on hydrometeorology, oceanography and ecology. The Caspian Research Institute of Fisheries (CaspNIRKH) traces its history from the Astrakhan Research Station [established in 1897, since 1930 the Volga-Caspian Scientific Fisheries Station, since 1948 the Caspian Branch of the All-Russian Research Institute of Fisheries and Oceanography, since 1954 the Caspian Research Institute of Marine Fisheries and Oceanography (KaspNIRO), modern name since 1965]. CaspNIRKh is developing the foundations for the conservation and rational use of the biological resources of the Caspian Sea. It consists of 18 laboratories and scientific departments - in Astrakhan, Volgograd and Makhachkala. It has a scientific fleet of more than 20 vessels.

Economic use. The natural resources of the Caspian Sea are rich and varied. Significant hydrocarbon reserves are being actively developed by Russian, Kazakh, Azerbaijani and Turkmen oil and gas companies. There are huge reserves of mineral self-saddle salts in the Kara-Bogaz-Gol Bay. The Caspian region is also known as a massive habitat for waterfowl and near-water birds. About 6 million migratory birds migrate through the Caspian Sea every year. In this regard, the Volga delta, Kyzylagadzh, Northern Cheleken and Turkmenbashi bays are recognized as sites of international rank under the Ramsar Convention. The estuarine sections of many rivers flowing into the sea have unique types of vegetation. The fauna of the Caspian Sea is represented by 1800 animal species, of which 415 species are vertebrates. More than 100 species of fish live in the sea and estuaries of rivers. are of commercial importance sea views- herring, sprat, gobies, sturgeons; freshwater - carp, perch; arctic "invaders" - salmon, white salmon. Major ports: Astrakhan, Makhachkala in Russia; Aktau, Atyrau in Kazakhstan; Turkmenbashi in Turkmenistan; Bandar Torkemen, Bandar Anzeli in Iran; Baku in Azerbaijan.

Ecological state. The Caspian Sea is under a powerful anthropogenic impact due to the intensive development of hydrocarbon deposits and the active development of fishing. In the 1980s, the Caspian Sea produced up to 80% of the world's sturgeon catch. Predatory catches of recent decades, poaching and a sharp deterioration in the ecological situation have put many valuable fish species on the brink of extinction. Habitat conditions have deteriorated not only for fish, but also for birds and marine animals (Caspian seal). The countries washed by the waters of the Caspian Sea are faced with the problem of creating a set of international measures to prevent pollution of the aquatic environment and developing the most effective environmental strategy for the near future. A stable ecological state is noted only in parts of the sea remote from the coast.

Lit.: Caspian Sea. M., 1969; Complex studies of the Caspian Sea. M., 1970. Issue. one; Gul K.K., Lappalainen T.N., Polushkin V.A. The Caspian Sea. M., 1970; Zalogin B. S., Kosarev A. N. Morya. M., 1999; International tectonic map of the Caspian Sea and its framing / Ed. V. E. Khain, N. A. Bogdanov. M., 2003; Zonn I. S. Caspian Encyclopedia. M., 2004.

M. G. Deev; V. E. Khain (geological structure of the bottom).

The territory of Russia is washed by twelve seas belonging to the basins of three oceans. But one of these seas - the Caspian - is often called a lake, which sometimes confuses people who are poorly versed in geography.

Meanwhile, it is really more correct to call the Caspian a lake, not a sea. Why? Let's figure it out.

A bit of geography. Where is the Caspian Sea located?

Occupying an area that exceeds 370,000 square kilometers, the Caspian Sea stretches from north to south, dividing Europe and Asia with its water surface. Its coastline belongs to five different countries: Russia, Kazakhstan, Azerbaijan, Turkmenistan and Iran. Geographers conditionally divide its water area into three parts: Northern (25% of the area), Middle (36% of the area) and South Caspian (39% of the area), which differ in climate, geological setting and natural features. The coastline is mostly flat, indented by river channels, covered with vegetation, and in the northern part, where the Volga flows into the Caspian, it is also swampy.

The Caspian Sea has about 50 large and small islands, about a dozen bays and six large peninsulas. In addition to the Volga, about 130 rivers flow into it, and nine rivers form fairly wide and branched deltas. The annual drainage of the Volga is about 120 cubic kilometers. Together with other large rivers - the Terek, the Urals, the Emba and the Sulak - this accounts for up to 90% of the total annual runoff to the Caspian.

Why is the Caspian called a lake?

The main feature of any sea is the presence of straits connecting it with the ocean. The Caspian is a closed, or endorheic body of water, which receives river water, but does not connect with any ocean.

Its water contains a very small amount of salt compared to other seas (about 0.05%) and is considered slightly salty. Due to the lack of at least one strait connecting with the ocean, the Caspian is often called the largest lake in the world, since the lake is a completely closed reservoir, which is fed only by river water.

International maritime laws do not apply to the waters of the Caspian Sea, and its water area is divided among all countries that adjoin it, in proportion to the coastline.

Why is the Caspian called the sea?

Despite all of the above, most often in geography, as well as in international and domestic documents, the name “Caspian Sea” is used, and not “ Caspian lake". First of all, this is due to the size of the reservoir, which is much more typical for the sea than for the lake. Even, which is much smaller in area than the Caspian, locals often referred to as the sea. There are no other lakes in the world whose shores belong to five different countries at the same time.

In addition, attention should be paid to the structure of the bottom, which near the Caspian Sea has a pronounced oceanic type. Once the Caspian Sea, most likely, was connected with the Mediterranean, but tectonic processes and drying up separated it from the World Ocean. More than fifty islands are located in the Caspian Sea, and the area of some of them is quite large, even by international standards they are considered large. All this makes it possible to call the Caspian a sea, not a lake.

origin of name

Why is this sea (or lake) called Caspian? The origin of any name is often associated with ancient history terrain. Different peoples who lived on the shores of the Caspian called it differently. More than seventy names of this reservoir have been preserved in history - it was called the Hyrcanian, Derbent, Sarai Sea, etc.

Iranians and Azerbaijanis still call it the Khazar Sea. It began to be called Caspian by the name of the ancient tribe of nomadic horse breeders who lived in the steppes adjacent to its coast - a large tribe of Caspians. It was they who gave the name to the largest lake on our planet - the 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 a drainless 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, currently - about -28 m below the level of the World Ocean. The area of the Caspian Sea is currently approximately 371,000 km², the maximum depth is 1025 m.

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

The Caspian Sea is conditionally divided according to physical and geographical conditions into 3 parts - the Northern Caspian, the Middle Caspian and the Southern Caspian. The conditional border between the North and Middle Caspian is passed along the line Chechen (island) - Tyub-Karagansky cape, between the Middle and South Caspian - along the line Zhiloy (island) - Gan-Gulu (cape). The area of the Northern, Middle and Southern Caspian is 25, 36, 39 percent respectively.

Origin

According to one of the hypotheses, the Caspian Sea got its name in honor of the ancient tribes of horse breeders - the Caspians, who lived BC on southwest coast Caspian Sea. Throughout the history of its existence, the Caspian Sea had about 70 names for different tribes and peoples: the Hyrcanian Sea; The Khvalyn Sea or the Khvalis Sea is an ancient Russian name, derived from the name of the inhabitants of Khorezm, who traded in the Caspian Sea - Khvalis; Khazar Sea - the name in Arabic (Bahr-al-Khazar), Persian (Daria-e Khazar), Turkish and Azerbaijani (Khazar Denizi) languages; Abeskun Sea; Saray Sea; Derbent Sea; Sihai and other names. In Iran, the Caspian Sea is still called the Khazar or Mazenderan Sea (after the name of the people inhabiting the Iranian coastal province of the same name).

Data

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, the coastline is indented 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 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.

Islands

Large peninsulas of the Caspian Sea: Agrakhan Peninsula, Absheron Peninsula, Buzachi, Mangyshlak, Miankale, Tub-Karagan.

There are about 50 large and medium-sized islands in the Caspian Sea with a total area of approximately 350 square kilometers. The largest islands: Ashur-Ada, Garasu, Gum, Dash, Zira (island), Zyanbil, Kyur Dashy, Khara-Zira, Sengi-Mugan, Chechen (island), Chygyl.

gulfs

Large bays of the Caspian Sea: Agrakhansky Bay, Komsomolets (Gulf) (former Dead Kultuk, former Tsesarevich Bay), Kaydak, Mangyshlak, Kazakh (Gulf), Turkmenbashi (Gulf) (former Krasnovodsk), Turkmen (Gulf), Gyzylagach, Astrakhan ( bay), Gyzlar, Girkan (former Astarabad) and Enzali (former Pahlavi).

nearby lakes

Off the east coast is salt Lake Kara Bogaz Gol, until 1980 it 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 thousand kilometers) and about 150 thousand tons of salt enter Kara-Bogaz-Gol from the Caspian Sea.

Rivers

Swimming pool

Cities and states

The Caspian Sea washes the shores of five coastal states:

Russia (Dagestan, Kalmykia and Astrakhan region) - in the west and north-west, 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
Azerbaijan - in the southwest, the length of the coastline is 955 kilometers
The largest city - a port on the Caspian Sea - Baku, the capital of Azerbaijan, which is located in the southern part of the Absheron Peninsula and has 2,070 thousand people (2003). Other large Azerbaijani Caspian cities are Sumgayit, 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 the settlement of oil workers Neftyanye Kamni, whose facilities 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 shore of the Caspian Sea there is a 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 shore of the Krasnovodsk Bay - the Turkmen city of Turkmenbashi, formerly Krasnovodsk. Several Caspian cities are located on the southern (Iranian) coast, the largest of them is Anzali.

Dimensions

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 has amounted to 15 meters. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out 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 risen and in 1995 reached -26.7 m, since 1996 there has been a downward trend again. Scientists associate the causes of changes in the water level of the Caspian Sea with climatic, geological and anthropogenic factors.

Climate

The water temperature is subject to significant latitudinal changes, most pronounced in winter, when the temperature changes from 0 - 0.5 °C at the ice edge in the north of the sea to 10 - 11 °C in the south, that is, the water temperature difference is about 10 °C. For shallow water areas with depths less than 25 m, the annual amplitude can reach 25 - 26 °C. On average, the water temperature near the western coast is 1 - 2 °C higher than that of the eastern coast, and in the open sea the water temperature is 2 - 4 °C higher than near the coasts. According to the nature of the horizontal structure of the temperature field in the annual cycle of variability, three time intervals can be distinguished in the upper 2-m layer. From October to March, the water temperature increases in the south and east, which is especially evident in the Middle Caspian. Two stable quasi-latitudinal zones can be distinguished, where the 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 threshold, from 7 to 10 °C. During this period, the least chilled 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 faster warming 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 melting ice, but already in May the temperature rises here to 16 - 17 °C. In the middle part, the temperature at this time is 13 - 15 °C, and in the south it rises to 17 - 18 °C. The spring warming of the water 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, breaks 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 the 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 northwestern winds prevailing in the summer season. The wind of this direction causes the outflow of warm surface waters from the coast and the rise of colder waters from the intermediate layers. Upwelling starts in June, but it reaches its highest intensity in July-August. As a result, a decrease in temperature is observed on the surface of the water (7 - 15 °C). Horizontal temperature gradients reach 2.3 °C at the surface and 4.2 °C at a depth of 20 m. in June to 43 - 45 ° N in September. Summer upwelling is of great importance for the Caspian Sea, radically changing the dynamic processes in the deep water area. 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 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 shock layer are very significant and can reach several degrees per meter. In the middle part of the sea, due to the surge near the eastern coast, the shock layer rises close to the surface. Since there is no stable baroclinic layer in the Caspian Sea with a large potential energy reserve similar to the main thermocline of the World Ocean, with the cessation of the effect of the prevailing winds that cause upwelling, and with the onset of autumn-winter convection in October-November, the temperature fields are rapidly reorganized to the winter regime. In the open sea, the water temperature in the surface layer drops in the middle part to 12 - 13 °C, in the southern part to 16 - 17 °C. In the vertical structure, the shock layer is washed out due to convective mixing and disappears by the end of November.

Compound

The salt composition of the waters of the closed 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 in sea waters, an increase in the relative amount of carbonates, sulfates, and calcium, which are the main components in the chemical composition of river waters. The most conservative ions are potassium, sodium, chloride and magnesium. The least conservative are calcium and bicarbonate ion. In the Caspian Sea, the content of calcium and magnesium cations is almost two times higher than in the Sea of Azov, and sulfate anion is three times higher. The salinity of 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 saline bays-kultuks can reach 60 - 100 g/kg. In the Northern Caspian, during the entire ice-free period from April to November, a quasi-latitudinal salinity front 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 Northern 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 in the southern and eastern directions. Salinity increases insignificantly with depth (by 0.1 - 0.2 psu). In the deep-water part of the Caspian Sea, in the vertical salinity profile, characteristic isohaline troughs and local extrema are observed in the area of the eastern continental slope, which indicate the processes of near-bottom creep of waters becoming saline in the eastern shallow waters of the South Caspian. The salinity value also strongly depends on sea level and (which is interrelated) on the amount of continental runoff.

General information

The relief of the northern part of the Caspian is a shallow wavy plain with banks and accumulative islands, the average depth of the Northern Caspian is about 4 - 8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle. The Middle Caspian is quite deep, the depth of water in the Derbent depression reaches 788 meters. The Apsheron threshold separates the Middle and South Caspian. The South Caspian is considered 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, and in some areas there is an outcrop of bedrock.

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 - 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.

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

The circulation of water in the Caspian Sea is connected with the runoff and winds. Since most of the water flow falls on the Northern Caspian, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current is divided into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

The fauna of the Caspian is represented by 1809 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian world, 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. Since March 31, 2008, 363 dead seals have been found on the coast of the Caspian Sea in Kazakhstan.

(Visited 133 times, 1 visits today)