home Travel abroad Whether the Caspian lake. Why can the Caspian Sea be called neither a sea nor a lake? Kura - the largest river in Transcaucasia

Whether the Caspian lake. Why can the Caspian Sea be called neither a sea nor a lake? Kura - the largest river in Transcaucasia

The Caspian Sea is located on the border of Europe and Asia and is surrounded by the territories of five states: Russia, Azerbaijan, Iran, Turkmenistan and Kazakhstan. Despite its name, the Caspian Sea is the largest lake on the planet (its area is 371,000 km2), but the bottom is composed of oceanic crust and salt water along with large sizes give reason to consider it a sea. A large number of rivers flow into the Caspian Sea, for example, such large ones as the Volga, Terek, Ural, Kura and others.

Relief and depth of the Caspian Sea

Based on the bottom topography, the Caspian Sea is divided into three parts: southern (the largest and deepest), middle and northern.

In the northern part, the depth of the sea is the smallest: on average it ranges from four to eight meters, and the maximum depth here reaches 25 m. The northern part of the Caspian Sea is limited by the Mangyshlak Peninsula and occupies 25% of the total area of the reservoir.

The middle part of the Caspian Sea is deeper. Here average depth becomes equal to 190 m, while the maximum is 788 meters. The area of the middle Caspian Sea is 36% of the total, and the volume of water is 33% of the total volume of the sea. It is separated from the southern part by the Absheron Peninsula in Azerbaijan.

The deepest and largest part of the Caspian Sea is the southern one. It occupies 39% of the total area, and its share of the total water volume is 66%. Here is the South Caspian depression, which contains the most deep point sea – 1025 m.

Islands, peninsulas and bays of the Caspian Sea

There are about 50 islands in the Caspian Sea, almost all of them are uninhabited. Due to the shallower depth of the northern part of the sea, most of the islands are located there, among them the Baku archipelago belonging to Azerbaijan, the Seal Islands in Kazakhstan, as well as many Russian islands off the coast of the Astrakhan region and Dagestan.

Among the peninsulas of the Caspian Sea, the largest are Mangyshlak (Mangistau) in Kazakhstan and Absheron in Azerbaijan, on which such big cities as the capital of the country Baku and Sumgayit.

Kara-Bogaz-Gol Bay Caspian Sea

The coastline of the sea is very indented, and there are many bays on it, for example, Kizlyarsky, Mangyshlaksky, Dead Kultuk and others. The Kara-Bogaz-Gol Bay deserves special mention, which is actually a separate lake connected to the Caspian Sea by a narrow strait, thanks to which it maintains a separate ecosystem and higher salinity of water.

Fishing in the Caspian Sea

Since ancient times, the Caspian Sea has attracted residents of its shores with its fish resources. About 90% of the world's sturgeon production is caught here, as well as fish such as carp, bream, and sprat.

Caspian Sea video

In addition to fish, the Caspian Sea is extremely rich in oil and gas, the total reserves of which are about 18-20 million tons. Salt, limestone, sand and clay are also mined here.

If you liked this material, share it with your friends on in social networks. Thank you!

The Caspian Sea is the largest closed lake on Earth, located at the junction of Europe and Asia, called a sea due to the fact that its bed is composed of oceanic-type crust. The Caspian Sea is an endorheic lake, and the water in it is salty, from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data it was 27.16 m below sea level. The Caspian Sea is located at the junction of two parts of the Eurasian continent - Europe and Asia. The length of the Caspian Sea from north to south is approximately 1200 kilometers, from west to east - from 195 to 435 kilometers, on average 310-320 kilometers. The Caspian Sea is conventionally divided according to physical and geographical conditions into 3 parts - the Northern Caspian, the Middle Caspian and the Southern Caspian. The conditional border between the Northern and Middle Caspian runs along the line of the island. Chechen - Cape Tyub-Karagansky, between the Middle and Southern Caspian Sea - along the line of the island. Residential - Cape Gan-Gulu. The area of the Northern, Middle and Southern Caspian Sea is 25, 36, 39 percent, respectively.

Length coastline The Caspian Sea is estimated at approximately 6500-6700 kilometers, with islands - up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low-lying and smooth. In the northern part, the coastline is indented by water channels and islands of the Volga and Ural deltas, the banks are low and swampy, and the water surface in many places is covered with thickets. The east 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 Gulf and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian region.

Bottom relief The relief of the northern part of the Caspian Sea is a shallow undulating plain with banks and accumulative islands, the average depth of the Northern Caspian Sea is 4-8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle Caspian. The Middle Caspian is quite deep, the water depth in the Derbent depression reaches 788 meters. The Absheron threshold separates the Middle and Southern Caspian Seas. The Southern Caspian is considered deep-sea; the water depth in the South Caspian depression reaches 1025 meters from the surface of the Caspian Sea. Shell sands are widespread on the Caspian shelf, deep-sea areas are covered with silty sediments, and in some areas there is an outcrop of bedrock. Temperature Water temperature is subject to significant latitudinal changes, most clearly expressed in winter, when the temperature varies from 0-0.5 °C at the ice edge in the north of the sea to 10-11 °C in the south, that is, the water temperature difference is about 10 °C . For shallow water areas with depths less than 25 m, the annual amplitude can reach 25-26 °C. On average, the water temperature off the west coast is 1-2 °C higher than that on the east, and in the open sea the water temperature is 2-4 °C higher than off the coasts.

Animal and plant life The fauna of the Caspian Sea is represented by 1809 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian Sea, where most of the world's sturgeon stocks are concentrated, as well as freshwater fish such as roach, carp, and pike perch. The Caspian Sea is the habitat of fish such as carp, mullet, sprat, kutum, bream, salmon, perch, and pike. The Caspian Sea is also home to a marine mammal - the Caspian seal. The flora of the Caspian Sea and its coast is represented by 728 species. The predominant plants in the Caspian Sea are algae - blue-green, diatoms, red, brown, characeae and others, and flowering plants - zoster and ruppia. In origin, the flora is predominantly of Neogene age, but some plants were brought into the Caspian Sea by humans deliberately or on the bottoms of ships.

Minerals Many oil and gas fields are being developed in the Caspian Sea. Proven oil resources in the Caspian Sea amount to about 10 billion tons, shared resources 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. In the second half of the 19th century, oil production began on an industrial scale on the Absheron Peninsula, and then in other territories. In addition to oil and gas production, salt, limestone, stone, sand, and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.

The Caspian Sea is the largest enclosed body of water on planet Earth, located on the continent of Eurasia - in the border territory of the states of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. In fact it is giant lake, left after the disappearance of the ancient Tethys Ocean. Nevertheless, there is every reason to consider it as an independent sea (this is indicated by its salinity, large area and considerable depth, a bottom made of oceanic crust and other signs). In terms of maximum depth, it is the third among closed reservoirs - after lakes Baikal and Tanganyika. In the northern part of the Caspian Sea (several kilometers from the northern shore - parallel to it) passes geographical boundary between Europe and Asia.

Toponymy

Other names: throughout the history of mankind, the Caspian Sea has had about 70 different names among different peoples. The most famous of them: Khvalynskoye or Khvalisskoye (took place during the Ancient Rus', arose from the name of the people praises, who lived in the Northern Caspian region and traded with the Russians), Girkanskoe or Dzhurdzhanskoe (derived from alternative names for the city of Gorgan, located in Iran), Khazar, Abeskunskoe (after the name of the island and city in the Kura delta - now flooded), Saraiskoe, Derbentskoe, Sikhai .
Origin of name: according to one hypothesis, its modern and most ancient name, The Caspian Sea received from a tribe of nomadic horse breeders Caspian Sea, who lived in the 1st millennium BC on the southwestern coast.

Morphometry

Catchment area: 3,626,000 km².
Mirror area: 371,000 km².
Coastline length: 7,000 km.
Volume: 78,200 km³.
Average depth: 208 m.
Maximum depth: 1,025 m.

Hydrology

Availability of permanent flow: no, drainless.
Tributaries:, Ural, Emba, Atrek, Gorgan, Heraz, Sefidrud, Astarchay, Kura, Pirsagat, Kusarchay, Samur, Rubas, Darvagchay, Ulluchay, Shuraozen, Sulak, Terek, Kuma.
Bottom: very diverse. At shallow depths, sandy soil with an admixture of shells is common; in deep-sea areas, it is silty. In the coastal strip there may be pebbly and rocky places (especially where mountain ranges adjoin the sea). In the estuarine areas, the underwater soil consists of river sediments. The Kara-Bogaz-Gol Bay is notable for the fact that its bottom is a thick layer of mineral salts.

Chemical composition

Water: salty.
Salinity: 13 g/l.
Transparency: 15 m.

Geography

Rice. 1. Map of the Caspian Sea basin.

Coordinates: 41°59′02″ n. latitude, 51°03′52″ e. d.
Height above sea level:-28 m.
Coastal landscape: due to the fact that the coastline of the Caspian Sea is very long, and it itself is located in different geographical areas— The coastal landscape is diverse. In the northern part of the reservoir, the banks are low, swampy, and in the deltas of large rivers, they are cut by numerous channels. Eastern Shores for the most part limestone - desert or semi-desert. Western and southern shore adjacent to mountain ranges. The greatest ruggedness of the coastline is observed in the west, in the area of the Absheron Peninsula, and also in the east, in the area of the Kazakh and Kara-Bogaz-Gol bays.
Settlements on the banks:
- Russia: Astrakhan, Derbent, Kaspiysk, Makhachkala, Olya.
- Kazakhstan: Aktau, Atyrau, Kuryk, Sogandyk, Bautino.
- Turkmenistan: Ekerem, Karabogaz, Turkmenbashi, Khazar.
- Iran: Astara, Balboser, Bender-Torkemen, Bender-Anzeli, Neka, Chalus.
- Azerbaijan: Alyat, Astara, Baku, Dubendi, Lankaran, Sangachali, Sumgayit.

Interactive map

Ecology

The ecological situation in the Caspian Sea is far from ideal. Almost all large rivers flowing into it are polluted by wastewater from industrial enterprises located upstream. This could not but affect the presence of pollutants in the waters and bottom sediments of the Caspian Sea - over the past half century, their concentration has increased significantly, and the content of some heavy metals has already exceeded permissible standards.

In addition, the waters of the Caspian Sea are constantly polluted by domestic wastewater from coastal cities, as well as during oil production on the continental shelf, and during its transportation.

Fishing on the Caspian Sea

Types of fish:
Artificial settlement: not all of the above fish species in the Caspian Sea are native. About 4 dozen species were found by chance (for example, through canals from the Black and Baltic seas), or were deliberately inhabited by humans. As an example, it is worth citing mullets. Three Black Sea species of these fish - mullet, sharpnose and singil - were released in the first half of the 20th century. The mullet did not take root, but the mullet and the singil have successfully acclimatized, and by now have settled virtually throughout the entire Caspian waters, forming several commercial herds. At the same time, the fish fatten up faster than in the Black Sea and reach larger sizes. In the second half of the last century (starting from 1962), attempts were also made to introduce such Far Eastern salmon fish as pink salmon and chum salmon into the Caspian Sea. In total, several billion fry of these fish were released into the sea over the course of 5 years. Pink salmon did not survive in the new habitat, chum salmon, on the contrary, successfully took root and even began to enter the rivers flowing into the sea to spawn. However, it was unable to reproduce in sufficient quantities and gradually disappeared. There are still no favorable conditions for its full natural reproduction (there are very few places where spawning and development of fry could successfully occur). To provide them, river reclamation is necessary, otherwise, without human help (artificial collection of eggs and their incubation), the fish will not be able to maintain their numbers.

Fishing spots

In fact, fishing is possible anywhere on the Caspian Sea coast, which can be reached by land or water. What types of fish will be caught depends on local conditions, but to a greater extent on whether the rivers flow here. As a rule, in places where estuaries and deltas are located (especially large watercourses), the water in the sea is greatly desalinated, so freshwater fish (carp, catfish, bream, etc.) usually predominate in the catches; species characteristic of the flowing rivers may also be found. rivers (usachi, shemaya). Of the marine species in desalinated areas, those for which salinity does not matter (mullet, some gobies) are caught. At certain periods of the year, semi-anadromous and anadromous species can be found here, feeding in the sea and entering rivers to spawn (sturgeon, some herrings, Caspian salmon). In places where there are no flowing rivers, freshwater species are found in slightly smaller numbers, but marine fish also appear, usually avoiding desalinated areas (for example, sea pike perch). Far from the coast, fish are caught that prefer salt water, and deep-sea species.

Conventionally, we can distinguish 9 places or areas that are interesting in terms of fishing:

North Shore (RF)- this site is located on the northern coast of the Russian Federation (from the Volga delta to the Kizlyar Bay). Its main features are low salinity of water (the lowest in the Caspian Sea), shallow depth, the presence of multiple shoals, islands, and highly developed aquatic vegetation. In addition to the Volga delta with its numerous channels, bays and eriks, it also includes the estuary coastal area, called the Caspian Peaks. These places are popular among Russian fishermen, and for good reason: the conditions for fish here are very favorable, and there is also a good food supply. The ichthyofauna in these parts may not shine with a wealth of species, but it is distinguished by its abundance, and some of its representatives reach quite considerable sizes. Typically, the bulk of the catches are freshwater fish characteristic of the Volga basin. Most often caught: perch, pike perch, roach (more precisely, its varieties called roach and ram), rudd, asp, sabrefish, bream, silver carp, carp, catfish, pike. Somewhat less common are black bream, silver bream, white-eye, and bluegill. Representatives of sturgeons (sturgeon, stellate sturgeon, beluga, etc.) and salmonids (nelma, brown trout - Caspian salmon) are also found in these places, but their fishing is prohibited.
Northwestern coast (RF)- this area covers West Coast Russian Federation(from Kizlyar Bay to Makhachkala). The rivers Kuma, Terek and Sulak flow here - they carry their waters both through natural channels and artificial canals. There are bays in this area, some of which are quite large (Kizlyarsky, Agrakhansky). The sea in these places is shallow. Freshwater fish predominate in the catches: pike, perch, carp, catfish, rudd, bream, barbel, etc., and marine species are also caught here, for example, herring (blackback, bellyfish).
West Bank (RF)- from Makhachkala to the border of the Russian Federation with Azerbaijan. An area where mountain ranges adjoin the sea. The salinity of the water here is slightly higher than in previous places, so marine species are more common in fishermen's catches (sea pike perch, mullet, herring). However, freshwater fish are by no means uncommon.
West Bank (Azerbaijan)- from the border of the Russian Federation with Azerbaijan along the Absheron Peninsula. Continuation of the area where mountain ranges adjoin the sea. Fishing here is even more similar to typical offshore fishing, with fish such as razorback and mullet and several species of gobies also caught here. In addition to them, there are kutum, herring, and some typically freshwater species, for example, carp.
Southwestern coast (Azerbaijan)- from the Absheron Peninsula to the border of Azerbaijan with Iran. Most of this area is occupied by the Kura River delta. The same types of fish that were listed in the previous paragraph are caught here, but freshwater ones are somewhat more common.
Northern coast (Kazakhstan)- this section covers the northern coast of Kazakhstan. The Ural delta and the Akzhaiyk state reserve are located here, so fishing directly in the river delta and in some adjacent water areas is prohibited. Fishing can only be done outside the reserve - upstream from the delta, or in the sea - at some distance from it. Fishing near the Ural delta has much in common with fishing at the confluence of the Volga - almost the same species of fish are found here.
Northeast coast (Kazakhstan)- from the mouth of the Emba to Cape Tyub-Karagan. Unlike the northern part of the sea, where the water is greatly diluted by large rivers flowing in, its salinity here increases slightly, so those species of fish appear that avoid desalinated areas, for example, sea pike perch, which is fished in Dead Kultuk Bay. Also, other representatives of marine fauna are often found in the catches.
Eastern coast (Kazakhstan, Turkmenistan)- from Cape Tyub-Karagan to the border of Turkmenistan and Iran. It is distinguished by the almost complete absence of flowing rivers. The salinity of the water here is at its maximum. Of the fish in these places, marine species predominate; the bulk of the catches are mullet, sea pike perch and gobies.
South Bank (Iran)- covers South coast Caspian Sea. Throughout this section, the Elborz mountain range adjoins the sea. Many rivers flow here, most of which are small streams, there are also several medium-sized and one large river. Of the fish, in addition to marine species, there are also some freshwater, as well as semi-anadromous and anadromous species, for example, sturgeon.

Fishing Features

The most popular and catchy amateur tackle used on the Caspian coast is a heavy spinning rod, converted into a “sea bottom”. It is usually equipped with a durable reel on which a fairly thick fishing line (0.3 mm or more) is wound. The thickness of the fishing line is determined not so much by the size of the fish, but by the mass of a fairly heavy sinker, which is necessary for ultra-long casting (in the Caspian Sea it is widely believed that the farther from the shore the casting point is, the better). After the sinker comes a thinner line - with several leashes. Shrimps and amphipods that live in coastal algae thickets are used as bait - if fishing is intended sea fish, or a regular bait like a worm, chafer larvae and others - if there are freshwater species in the fishing area.

At the mouths of inflowing rivers, other gear may be used, such as float rod, feeder and traditional spinning rod.

kasparova2 majorov2006 g2gg2g-61 .

Photo 8. Sunset in Aktau.

CASPIAN SEA (Caspian), the largest on globe closed reservoir, closed brackish lake. Located on the southern border of Asia and Europe, it washes the shores of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. Due to the size, originality natural conditions and the complexity of hydrological processes, the Caspian Sea is usually classified as a closed inland sea.

The Caspian Sea is located in a vast area of internal drainage and occupies a deep tectonic depression. The water level in the sea is about 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 extends along the meridian for 1030 km.

The largest bays: in the east - Mangyshlaksky, Kara-Bogaz-Gol, Turkmenbashi (Krasnovodsky), Turkmensky; in the west - Kizlyarsky, Agrakhansky, Kizilagaj, Baku Bay; in the south there are shallow lagoons. There are many islands in the Caspian Sea, but almost all of them are small, with total area less than 2 thousand km 2. In the northern part there are numerous small islands adjacent to the Volga delta; larger ones are Kulaly, Morskoy, Tyuleniy, Chechen. Off the western shores are the Absheron archipelago, to the south lie the islands of the Baku archipelago, east coast- a narrow island, stretched from north to south, Ogurchinsky.

The northern shores of the Caspian Sea are low-lying and very sloping, characterized by the widespread development of drying areas formed as a result of surge phenomena; deltaic shores are also developed here (deltas of the Volga, Ural, Terek) with an abundant supply of terrigenous material; the Volga delta with extensive reed thickets stands out. The western shores are abrasive, south of the Absheron Peninsula, mostly accumulative deltaic type with numerous bay bars and spits. The southern shores are low. The eastern shores are mostly deserted and low-lying, composed of sand.

Relief and geological structure bottom.

The Caspian Sea is located in a zone of increased seismic activity. In the city of Krasnovodsk (now Turkmenbashi) in 1895, a powerful earthquake measuring 8.2 on the Richter scale occurred. On the islands and coast of the southern part of the sea, eruptions of mud volcanoes are often observed, leading to the formation of new shoals, banks and small islands, which are eroded by waves and appear again.

Based on the peculiarities of physical-geographical conditions and the nature of the bottom topography in the Caspian Sea, it is customary to distinguish the Northern, Middle and Southern Caspian Seas. The Northern Caspian Sea is distinguished by exceptionally shallow waters, located entirely within the shelf with average depths of 4-5 m. Even small changes in the level here on low-lying coasts lead to significant fluctuations in the area of the water surface, therefore the boundaries of the sea in the northeastern part are shown with a dotted line on small-scale maps. The greatest depths (about 20 m) are observed only near the conventional border with the Middle Caspian, which is drawn along a line connecting the island of Chechen (north of the Agrakhan Peninsula) with Cape Tyub-Karagan on the Mangyshlak Peninsula. The Derbent depression (maximum depth 788 m) stands out in the bottom topography of the Middle Caspian Sea. The border between the Middle and Southern Caspian Sea passes over the Absheron threshold with depths of up to 180 m along a line from Chilov Island (east of the Absheron Peninsula) to Cape Kuuli (Turkmenistan). The Southern Caspian basin 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 is in the Middle Caspian, and less than 1% of the Caspian waters are located in the Northern Caspian due to shallow depths. In general, the topography of the Caspian Sea bottom is dominated by shelf areas (the entire northern part and a wide strip along the eastern coast of the 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-shelly sands, shell, and oolitic sands are common; deep-sea areas of the bottom are covered with siltstone and silty sediments with a high content of calcium carbonate. In some areas of the bottom, bedrock of Neogene age is exposed. Mirabilite accumulates in the Kara-Bogaz-Gol Bay.

Tectonically, within the Northern Caspian Sea, the southern part of the Caspian syneclise of the Eastern European Platform is distinguished, which in the south is framed by the Astrakhan-Aktobe zone, composed of Devonian-Lower Permian carbonate rocks that lie on a volcanic base and contain large deposits of oil and natural combustible gas. From the southwest, Paleozoic folded formations of the Donetsk-Caspian zone (or Karpinsky ridge) are thrust onto the syneclise, which is a protrusion of the foundation of the young Scythian (in the west) and Turanian (in the east) platforms, which are separated at the bottom of the Caspian Sea by the Agrakhan-Gurievsky fault (left shear) of northeastern strike. The Middle Caspian mainly belongs to the Turanian 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 deposits of oil and combustible gas in local uplifts. The Absheron threshold, separating the Middle Caspian from the South, is a connecting link of the Cenozoic folded systems of the Greater Caucasus and 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 deposits hydrocarbons.

Until the end of the Miocene, the Caspian Sea was a marginal sea of the ancient Tethys Ocean (from the Oligocene - the relict oceanic basin of the Paratethys). By the beginning of the Pliocene, it lost contact with the Black Sea. The Northern and Middle Caspian Seas were drained, and the paleo-Volga valley stretched through them, the delta of which was located in the Absheron Peninsula region. Delta sediments have become the main reservoir of oil and natural combustible gas deposits in Azerbaijan and Turkmenistan. In the late Pliocene, in connection with the Akchagyl transgression, the area of the Caspian Sea greatly increased and the connection with the World Ocean was 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 Quaternary time, transgressions (Apsheron, 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 west coast it is warm temperate, the southwestern and southern coasts lie within the subtropics, and on the east coast a desert climate prevails. IN winter time over the Northern and Middle Caspian, the weather is formed under the influence of Arctic continental and sea air, and the Southern Caspian is often under the influence of southern cyclones. The weather in the west is unstable and 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 ones are influenced by the Iran-Afghan minimum, which together creates dry, stable warm weather. Over the sea, winds prevail in the northern and northwestern (up to 40%) and southeastern (about 35%) directions. Average wind speed is about 6 m/s, in central regions sea up to 7 m/s, in the area of the Absheron Peninsula - 8-9 m/s. Northern storm “Baku Nords” reach speeds of 20-25 m/s. The lowest average monthly air temperatures -10 °C are observed in January - February in the northeastern regions (in the most severe winters they reach -30 °C), in the southern regions 8-12 °C. In July - August, average monthly temperatures over the entire sea area are 25-26 °C, with a maximum of 44 °C 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. The open sea receives an average of about 200 mm of precipitation per year.

Hydrological regime. Changes in the water balance of an enclosed sea greatly influence changes in the volume of water and corresponding fluctuations in level. 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 to Kara-Bogaz- Gol 13/3, which forms a negative water balance of 9 km 3, or 3 cm of 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. Since the beginning of the 20th century, level fluctuations have shown a steady downward trend, as a result of which over 75 years the level dropped by 3.2 m and in 1977 reached -29 m (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 unevenness of river flow (primarily the Volga runoff), therefore the lowest level is observed in winter, the highest in summer. Short-term sharp changes in level are associated with surge phenomena and are most pronounced in shallow waters. northern regions and during storm surges can reach 3-4 m. Such surges cause flooding of large coastal areas of land. In the Middle and Southern Caspian Sea, surge fluctuations in level average 10-30 cm, under storm conditions - up to 1.5 m. The frequency of surges, depending on the region, is from one to 5 times a month, lasting up to one day. In the Caspian Sea, as in any closed body of water, seiche level fluctuations are observed in the form of standing waves with periods of 4-9 hours (wind) and 12 hours (tidal). The magnitude of seiche vibrations 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 and the Urals and enters the shallow Northern Caspian Sea. The rivers of the western coast - Kura, Samur, Sulak, Terek, etc. - provide up to 10% of the flow. About 5% more fresh water brought to the South Caspian by rivers of the Iranian coast. The eastern desert shores are completely deprived of constant fresh flow.

The average speed of wind currents is 15-20 cm/s, the highest - up to 70 cm/s. In the Northern Caspian Sea, 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. Near 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 Southern Caspian and turns north, joining the coastal current that goes around the entire eastern coast. The average state of movement of Caspian surface waters is often disturbed due to variability in wind conditions and other factors. Thus, in the northeastern shallow area, a local anticyclonic gyre may arise. Two anticyclonic eddies are often observed in the Southern Caspian Sea. In the Middle Caspian in the warm season, stable northwest winds create southerly transport along the eastern coast. In light winds and during calm weather, currents may have other directions.

Wind waves develop very strongly, since the prevailing winds have longer length acceleration The disturbance develops mainly in the northwest and southeast directions. Strong storms are observed in the open waters of the Middle Caspian Sea, in the areas of Makhachkala, the Absheron Peninsula and the Mangyshlak Peninsula. Average height waves of greatest frequency are 1-1.5 m, at wind speeds of more than 15 m/s it increases to 2-3 m. The highest wave heights are recorded during strong storms in the area of the Neftyanye Kamni hydrometeorological station: annually 7-8 m, in some cases up to 10 m .

The water temperature on the sea surface in January - February in the Northern Caspian Sea is close to freezing temperature (about -0.2 - -0.3 °C) and gradually increases in south direction up to 11 °C off the coast of Iran. In summer, surface waters warm up to 23-28 °C everywhere, except for the eastern shelf of the Middle Caspian Sea, where in July - August seasonal coastal upwelling develops and the surface water temperature drops to 12-17 °C. In winter, due to intense convective mixing, the water temperature changes little with depth. In summer, under the upper heated layer at horizons of 20-30 m, a seasonal thermocline (a layer of sharp temperature changes) is formed, separating deep cold waters from warm surface ones. In the bottom layers of water in deep-sea depressions, the temperature remains 4.5-5.5 °C all year round in the Middle Caspian and 5.8-6.5 °C in the Southern Caspian. Salinity in the Caspian Sea is almost 3 times lower than in open areas of the World Ocean, averaging 12.8-12.9‰. It should be especially emphasized that the salt composition of Caspian water is not completely identical to the composition 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 carbonates and sulfates of calcium and magnesium 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 areas of the Volga and Ural the water is fresh (less than 1‰), and as we 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. The differences in salinity between the Middle and Southern Caspian Seas are small; salinity increases slightly from northwest to southeast, reaching 13.6‰ in the Turkmen Gulf (in Kara-Bogaz-Gol up to 300‰). Vertical changes in salinity are small and rarely exceed 0.3‰, which indicates good vertical mixing water Water transparency varies widely 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 is classified as a partially frozen sea. Ice conditions are observed annually only in the northern regions. The Northern Caspian is completely covered by sea ice, the Middle Caspian is partially covered (only in severe winters). Middle border sea ice runs along an arc convex to the north, from the Agrakhan Peninsula in the west to the Tyub-Karagan Peninsula in the east. Ice formation usually begins in mid-November in the extreme northeast and gradually spreads to the southwest. In January, the entire Northern Caspian Sea is covered with ice, mostly fast ice (immobile). Drifting ice borders the fast ice with a strip 20-30 km wide. The average ice thickness is from 30 cm at the southern border to 60 cm in the northeastern regions of the Northern Caspian Sea, in hummocky accumulations - 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 south, along the western coast, sometimes to the Absheron Peninsula. At the beginning of April, the sea is completely free of ice cover.

History of the study. It is believed that the modern name of the Caspian Sea comes from the ancient Caspian tribes who inhabited the coastal areas 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 claim that this body of water is isolated, that is, it is a lake. In the works of Arab scientists of the Middle Ages there is information that in the 13th-16th centuries the Amu Darya partially flowed into this sea through one of its 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 actually arbitrary drawings. By order of Tsar Peter I, in 1714-15, an expedition was organized 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. Soimonov and K. Verdun. In 1731, Soimonov published the first atlas, and soon the first printed sailing guide of the Caspian Sea. A new edition of 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, and at the beginning of the 19th century by A.E. Kolodkin, who for the first time carried out instrumental compass surveying of the coast. Published in 1807 new map Caspian Sea, compiled taking into account the latest inventories. In 1837, systematic instrumental observations of sea level fluctuations began in Baku. The first was completed in 1847 Full description Gulf of Kara-Bogaz-Gol. In 1878, a 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, 1914-15, under the leadership of N. M. Knipovich, expeditionary research was carried out on the hydrology and hydrobiology of the Caspian Sea; in 1934, the Commission for the Comprehensive Study of the Caspian Sea was created at the USSR Academy of Sciences. A great contribution to the study of the geological structure and oil content of the Absheron 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, comprehensive research was launched in the Caspian Sea, aimed at studying the hydrometeorological regime, biological conditions and geological structure of the sea.

In the 21st century in Russia, two large scientific centers are engaged in solving the problems of the Caspian Sea. The Caspian Marine Research Center (CaspMNRC), created in 1995 by decree of the Government of the Russian Federation, conducts research work in hydrometeorology, oceanography and ecology. The Caspian Research Institute of Fisheries (CaspNIRKH) traces its history back to 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 (CaspNIRO), modern name since 1965]. CaspNIRH is developing the foundations for the conservation and rational use of 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. Natural resources The Caspian Sea is 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-sedimented salts in the Kara-Bogaz-Gol Bay. The Caspian region is also known as a massive habitat for waterfowl and semi-aquatic birds. About 6 million migratory birds migrate across the Caspian Sea every year. In this regard, the Volga delta, Kyzylagaj, Northern Cheleken and Turkmenbashi bays are recognized as sites of international rank within the framework of the Ramsar Convention. The mouth areas of many rivers flowing into the sea have unique types of vegetation. The fauna of the Caspian Sea is represented by 1800 species of animals, of which 415 are vertebrate species. More than 100 species of fish live in the sea and river mouths. Marine species are of commercial importance - herring, sprat, gobies, sturgeon; freshwater - carp, perch; Arctic “invaders” - salmon, white fish. Major ports: Astrakhan, Makhachkala in Russia; Aktau, Atyrau in Kazakhstan; Turkmenbashi in Turkmenistan; Bender-Torkemen, Bender-Anzeli in Iran; Baku in Azerbaijan.

Ecological state. The Caspian Sea is under powerful anthropogenic influence due to the intensive development of hydrocarbon deposits and the active development of fishing. In the 1980s, the Caspian Sea provided up to 80% of the world's sturgeon catch. Predatory fishing in recent decades, poaching and a sharp deterioration of the environmental situation have brought many valuable fish species to the brink of extinction. The living conditions of not only fish, but also birds and sea animals (Caspian seal) have deteriorated. 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 observed only in parts of the sea remote from the coast.

Lit.: Caspian Sea. M., 1969; Comprehensive studies of the Caspian Sea. M., 1970. Issue. 1; Gul K.K., Lappalainen T.N., Polushkin V.A. Caspian Sea. M., 1970; Zalogin B.S., Kosarev A.N. Seas. M., 1999; International tectonic map of the Caspian Sea and its frame / 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 Caspian Sea is the largest enclosed body of water on planet Earth, located on the continent of Eurasia - in the border territory of the states of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. In fact, it is a giant lake left after the disappearance of the ancient Tethys Ocean. Nevertheless, there is every reason to consider it as an independent sea (this is indicated by its salinity, large area and considerable depth, a bottom made of oceanic crust and other signs). In terms of maximum depth, it is the third among closed reservoirs - after lakes Baikal and Tanganyika. In the northern part of the Caspian Sea (several kilometers from the northern shore - parallel to it) there is a geographical border between Europe and Asia.

Toponymy

Other names: throughout the history of mankind, the Caspian Sea has had about 70 different names among different peoples. The most famous of them: Khvalynskoe or Khvalisskoe (took place during the times of Ancient Rus', arose from the name of the people praises, who lived in the Northern Caspian region and traded with the Russians), Girkanskoe or Dzhurdzhanskoe (derived from alternative names for the city of Gorgan, located in Iran), Khazar, Abeskunskoe (after the name of the island and city in the Kura delta - now flooded), Saraiskoe, Derbentskoe, Sikhai .
Origin of name: According to one hypothesis, the Caspian Sea received its modern and most ancient name from a tribe of nomadic horse breeders Caspian Sea, who lived in the 1st millennium BC on the southwestern coast.

Morphometry

Catchment area: 3,626,000 km².
Mirror area: 371,000 km².
Coastline length: 7,000 km.
Volume: 78,200 km³.
Average depth: 208 m.
Maximum depth: 1,025 m.