Caspian Sea. Caspian Sea (largest lake)

CaspAndmOre(Caspian) - the largest enclosed body of water on Earth. In size, the Caspian Sea is much larger than such lakes as the Upper, Victoria, Huron, Michigan, Baikal. According to formal features, the Caspian Sea is an endorheic lake. However, given its large size, brackish waters and sea-like regime, this body of water is called the sea.

According to one hypothesis, the Caspian Sea (among the ancient Slavs - the Khvalyn Sea) got its name in honor of the Caspian tribes who lived before our era on its southwestern coast.

The Caspian Sea washes the shores of five states: Russia, Azerbaijan, Iran, Turkmenistan and Kazakhstan.

The Caspian Sea is elongated in the meridional direction and is located between 36°33' and 47°07' N latitude. and 45°43΄ and 54°03΄ E (without Kara-Bogaz-Gol Bay). The length of the sea along the meridian is about 1200 km; the average width is 310 km. The northern coast of the Caspian Sea is bordered Caspian lowland, eastern - deserts Central Asia; in the west, the mountains of the Caucasus approach the sea, in the south, near the coast, the Elburz ridge stretches.

The surface of the Caspian Sea is much lower than the level of the World Ocean. Its current level fluctuates around -27 ... -28 m. These levels correspond to the sea surface area of ​​​​390 and 380 thousand km 2 (without the Kara-Bogaz-Gol Bay), the volume of water is 74.15 and 73.75 thousand km 3, average depth is about 190 m.

The Caspian Sea is traditionally divided into three large parts: the North (24% of the sea area), the Middle (36%) and the South Caspian (40%), which differ significantly in morphology and regime, as well as the large and isolated Kara-Bogaz-Gol Bay. The northern, shelf part of the sea is shallow: its average depth is 5–6 m, maximum depths are 15–25 m, and the volume is less than 1% of the total water mass of the sea. The Middle Caspian is a separate basin with the area of ​​maximum depths in the Derbent depression (788 m); its average depth is about 190 m. In the South Caspian, the average and maximum depths are 345 and 1025 m (in the South Caspian depression); 65% of the water mass of the sea is concentrated here.

There are about 50 islands in the Caspian Sea with a total area of ​​approximately 400 km2; the main ones are Tyuleniy, Chechen, Zyudev, Konevsky, Dzhambaysky, Durneva, Ogurchinsky, Apsheronsky. length coastline about 6.8 thousand km, with islands - up to 7.5 thousand km. The shores of the Caspian Sea are diverse. In the northern and eastern parts, they are quite strongly indented. There are large bays Kizlyarsky, Komsomolets, Mangyshlaksky, Kazakhsky, Kara-Bogaz-Gol, Krasnovodsky and Turkmensky, many bays; at west coast- Kyzylagach. The largest peninsulas are Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak, Krasnovodsky, Cheleken and Apsheronsky. The most common banks are accumulative; areas with abrasion shores are found along the contour of the Middle and South Caspian.

More than 130 rivers flow into the Caspian Sea, the largest of which is the Volga. , Ural, Terek, Sulak, Samur, Kura, Sefidrud, Atrek, Emba (its runoff enters the sea only in high-water years). Nine rivers have deltas; the largest are located at the mouths of the Volga and Terek.

The main feature of the Caspian Sea, as a drainless reservoir, is instability and a wide range of long-term fluctuations in its level. This most important hydrological feature of the Caspian Sea has a significant impact on all its other hydrological characteristics, as well as on the structure and regime of river mouths, on coastal zones. In the Caspian Sea level varied in the range of ~200 m: from -140 to +50 m BS; in from -34 to -20 m BS. From the first third of the 19th century and until 1977, sea level dropped by about 3.8 m - to the lowest point in the last 400 years (-29.01 m BS). In 1978–1995 The level of the Caspian Sea rose by 2.35 m and reached -26.66 m BS. Since 1995, a certain downward trend has dominated - to -27.69 m BS in 2013.

During major north coast the Caspian shifted to Samarskaya Luka on the Volga, and perhaps even further. At maximum transgressions, the Caspian turned into a sewage lake: excess water flowed through the Kuma-Manych depression into the Sea of ​​Azov and further into the Black Sea. In extreme regressions South coast The Caspian was shifted to the Apsheron threshold.

Long-term fluctuations in the level of the Caspian are explained by changes in the structure of the water balance of the Caspian Sea. The sea level rises when the incoming part of the water balance (primarily river runoff) increases and exceeds the outgoing part, and decreases if the inflow of river waters decreases. The total water flow of all rivers averages 300 km 3 /year; while the five largest rivers account for almost 95% (the Volga provides 83%). During the period of the lowest sea level, in 1942–1977, the river flow was 275.3 km 3 / year (of which 234.6 km 3 / year is the flow of the Volga), precipitation - 70.9, underground flow - 4 km 3 /year, and evaporation and outflow to the Kara-Bogaz-Gol Bay - 354.79 and 9.8 km 3 /year. During the period of intensive sea level rise, in 1978-1995, respectively, 315 (Volga - 274.1), 86.1, 4, 348.79 and 8.7 km 3 / year; in the modern period - 287.4 (Volga - 248.2), 75.3, 4, 378.3 and 16.3 km 3 / year.

The intra-annual changes in the level of the Caspian Sea are characterized by a maximum in June–July and a minimum in February; the range of intra-annual level fluctuations is 30–40 cm. Surge-surge level fluctuations are manifested throughout the sea, but they are most significant in the northern part, where, with maximum surges, the level can rise by 2–4.5 m and the edge “retreat” by several tens of kilometers inland, and in case of surges - to drop by 1–2.5 m. Seiche and tidal level fluctuations do not exceed 0.1–0.2 m.

Despite the relatively small size of the reservoir in the Caspian Sea, there is strong excitement. highest heights waves in the South Caspian can reach 10–11 m. Wave heights decrease in the direction from south to north. Storm waves can develop at any time of the year, but more often and more dangerously in the cold half of the year.

The Caspian Sea is generally dominated by wind currents; nevertheless, runoff currents play an appreciable role on the estuarine coasts of large rivers. Cyclonic water circulation prevails in the Middle Caspian, and anticyclonic circulation in the South Caspian. In the northern part of the sea, the patterns of wind currents are more irregular and depend on the characteristics and variability of the wind, bottom topography and coastlines, river runoff and aquatic vegetation.

The water temperature is subject to significant latitudinal and seasonal changes. IN winter period it varies from 0–0.5 o C at the ice edge in the north of the sea to 10–11 o C in the south. In summer, the water temperature in the sea averages 23–28 o C, and in shallow coastal waters in the Northern Caspian it can reach 35–40 o C. At depths, a constant temperature is maintained: deeper than 100 m it is 4–7 o C.

In winter, only the northern part of the Caspian Sea freezes; in severe winter - the entire Northern Caspian and coastal zones Middle Caspian. Freezing in the Northern Caspian lasts from November to March.

The salinity of water changes especially sharply in the northern part of the sea: from 0.1‰ on the estuarine coasts of the Volga and Urals to 10–12‰ on the border with the Middle Caspian. In the Northern Caspian, the temporal variability of water salinity is also great. In the middle and southern parts In the sea, salinity fluctuations are small: basically it is 12.5–13.5‰, increasing from north to south and from west to east. The highest water salinity is in the Kara-Bogaz-Gol Bay (up to 300‰). With depth, the salinity of water increases slightly (by 0.1–0.3‰). The average salinity of the sea is about 12.5‰.

More than a hundred species of fish live in the Caspian Sea and the mouths of the rivers flowing into it. There are Mediterranean and Arctic invaders. The object of fishing is goby, herring, salmon, carp, mullet and sturgeon fish. The latter number five species: sturgeon, beluga, stellate sturgeon, spike and sterlet. The sea is capable of producing up to 500-550 thousand tons of fish annually if overfishing is not allowed. From marine mammals the endemic Caspian seal lives in the Caspian Sea. Every year 5-6 million waterfowl migrate through the Caspian region.

The economy of the Caspian Sea is connected with oil and gas production, shipping, fishing, extraction of seafood, various salts and minerals (Kara-Bogaz-Gol Bay), with the use of recreational resources. The explored 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 and gas are being produced on an ever-increasing scale. Used by the Caspian Sea and water transport, including along the river-sea and sea-river routes. The main ports of the Caspian Sea: Astrakhan, Olya, Makhachkala (Russia), Aktau, Atyrau (Kazakhstan), Baku (Azerbaijan), Nowshahr, Bender-Enzeli, Bender-Torkemen (Iran) and Turkmenbashi (Turkmenistan).

The economic activity and hydrological features of the Caspian Sea create a number of serious environmental and water management problems. Among them: anthropogenic pollution of river and sea ​​waters(mainly oil products, phenols and synthetic surfactants), poaching and the reduction of fish stocks, especially sturgeons; damage to the population and coastal economic activity due to large-scale and rapid changes in the level of the reservoir, the impact of numerous hazardous hydrological phenomena and hydrological and morphological processes.

The total economic damage for all the Caspian countries associated with the rapid and significant recent rise in the level of the Caspian Sea, the flooding of part of the coastal land, the destruction of coasts and coastal structures, was estimated at 15 to 30 billion US dollars. It took urgent engineering measures to protect the coast.

A sharp drop in the level of the Caspian Sea in the 1930s–1970s. led to less damage, but they were significant. The navigable approach channels became shallow, the shallow seashore at the mouths of the Volga and the Urals became heavily overgrown, which became an obstacle to the passage of fish into the rivers for spawning. It was necessary to build fish passages through the seasides mentioned above.

Among the unresolved problems is the lack of an international agreement on the international legal status of the Caspian Sea, the division of its water area, bottom and subsoil.

The Caspian Sea is the object of many years of research by specialists from all the Caspian states. Such domestic organizations as the State Oceanographic Institute, the Institute of Oceanology of the Russian Academy of Sciences, the Hydrometeorological Center of Russia, the Caspian Research Institute of Fisheries, the Faculty of Geography of the Moscow state university and etc.

The Caspian Sea is one of the most amazing enclosed bodies of water on Earth.

Over the centuries, the sea has changed more than 70 names. The modern came from the Caspians - the tribes inhabiting the central and southeastern part of Transcaucasia 2 thousand years BC.

Geography of the Caspian Sea

The Caspian Sea is located at the junction of Europe with Asia and is geographically divided into the South, North and Middle Caspian. The middle and northern part of the sea belongs to Russia, the southern part to Iran, the eastern part to Turkmenistan and Kazakhstan, and the southwestern part to Azerbaijan. For many years, the Caspian states have been dividing the Caspian water area among themselves, and quite sharply at that.

Lake or sea?

In fact, the Caspian Sea is the world's largest lake, but it has a number of marine features. These include: a large water mass of the reservoir, severe storms with high waves, ebbs and flows. But the Caspian has no natural connection with the World Ocean, which makes it impossible to call it a sea. At the same time, thanks to the Volga and artificially created channels, such a connection appeared. The salinity of the Caspian Sea is 3 times lower than the usual sea level, which does not allow classifying the reservoir as a sea.

There were times when the Caspian Sea was indeed part of the World Ocean. Several tens of thousands of years ago, the Caspian was connected to the Sea of ​​Azov, and through it to the Black and Mediterranean. As a result of long-term processes occurring in the earth's crust, formed Caucasian mountains that isolated the pond. Communication between the Caspian and Black Seas for a long time was carried out through the strait (Kumo-Manych depression) and gradually ceased.

Physical quantities

Area, volume, depth

The area, volume and depth of the Caspian Sea are not constant and directly depend on the water level. On average, the area of ​​\u200b\u200bthe reservoir is 371,000 km², the volume is 78,648 km³ (44% of all world lake water reserves).

(Depth of the Caspian Sea in comparison with lakes Baikal and Tanganyika)

The average depth of the Caspian is 208 m, the northern part of the sea is considered the shallowest. The maximum depth is 1025 m, noted in the South Caspian depression. In depth, the Caspian is second only to Baikal and Tanganyika.

The length of the lake from north to south is about 1200 km, from west to east an average of 315 km. The length of the coastline is 6600 km, with islands - about 7 thousand km.

coast

Basically, the coast of the Caspian Sea is low-lying and smooth. In the northern part, it is heavily indented by the river channels of the Urals and the Volga. The swampy local shores are located very low. The eastern shores are adjacent to semi-desert zones and deserts, covered with limestone deposits. The most winding coasts are in the west in the region of the Apsheron Peninsula, and in the east - in the area of ​​the Kazakh Gulf and Kara-Bogaz-Gol.

sea ​​water temperature

(The temperature of the Caspian Sea in different time of the year)

The average water temperature in the Caspian in winter ranges from 0 °C in the northern part to +10 °C in the south. In the waters of Iran, the temperature does not fall below +13 °C. With the onset of cold weather, the shallow northern part of the lake is covered with ice, which lasts for 2-3 months. The thickness of the ice cover is 25-60 cm, at especially low temperatures it can reach 130 cm. late autumn and in winter, drifting ice floes can be observed in the north.

In summer average temperature the surface of the water in the sea is + 24 °C. Most of the sea warms up to +25 °C ... +30 °C. Warm water and beautiful sandy, occasionally shell and pebble beaches create excellent conditions for a full-fledged beach holiday. In the eastern part of the Caspian Sea, near the city of Begdash, anomalously low water temperatures persist in the summer months.

Nature of the Caspian Sea

Islands, peninsulas, bays, rivers

The Caspian Sea includes about 50 large and medium-sized islands, the total area of ​​which is 350 km². The largest of them are: Ashur-Ada, Garasu, Gum, Dash and Boyuk-Zira. Most large peninsulas are: Agrakhan, Absheron, Buzachi, Mangyshlak, Miankale and Tyub-Karagan.

(Tyuleniy Island in the Caspian Sea, part of the Dagestan Reserve)

The largest bays of the Caspian include: Agrakhan, Kazakh, Kizlyar, Dead Kultuk and Mangyshlak. In the east is salt Lake Kara-Bogaz-Gol, previously a lagoon connected to the sea by a strait. In 1980, a dam was built on it, through which water from the Caspian goes to Kara-Bogaz-Gol, where it then evaporates.

130 rivers flow into the Caspian Sea, located mainly in its northern part. The largest of them: Volga, Terek, Sulak, Samur and Ural. The average annual runoff of the Volga is 220 km³. 9 rivers have a delta-shaped mouth.

Flora and fauna

About 450 species of phytoplankton live in the Caspian Sea, including algae, aquatic and flowering plants. Of the 400 species of invertebrates, worms, crustaceans and mollusks predominate. There are a lot of small shrimp in the sea, which is an object of fishing.

More than 120 species of fish live in the Caspian and the delta. Fishing objects are sprat (“Kilkin fleet”), catfish, pike, bream, pike perch, kutum, mullet, vobla, rudd, herring, white fish, pike perch, goby, grass carp, burbot, asp and pike perch. Stocks of sturgeon and salmon are currently depleted, however, the sea is the largest supplier of black caviar in the world.

Fishing in the Caspian Sea is allowed all year round except for the period from late April to late June. On the coast there are many fishing bases with all amenities. Fishing in the Caspian is a great pleasure. In any part of it, including in large cities, the catch is unusually rich.

The lake is famous for its large variety of waterfowl. Geese, ducks, loons, gulls, waders, sea eagles, geese, swans and many others come to the Caspian during migration or nesting. The largest number of birds - over 600 thousand individuals is observed in the mouths of the Volga and the Urals, in the bays of Turkmenbashi and Kyzylagach. During the hunting season, a huge number of fishermen come here not only from Russia, but also from countries near and far abroad.

The only mammal lives in the Caspian Sea. This is the Caspian seal or seal. Until recently, the seals swam close to the beaches, everyone could admire the amazing animal with round black eyes, the seals behaved very friendly. Now the seal is on the verge of extinction.

Cities on the Caspian Sea

Baku is the largest city on the coast of the Caspian Sea. The number of one of the most most beautiful cities of the world is over 2.5 million people. Baku is spread out on the most picturesque Absheron peninsula and is surrounded on three sides by the waters of the warm and oil-rich Caspian Sea. Smaller cities: the capital of Dagestan - Makhachkala, Kazakh Aktau, Turkmen Turkmenbashi and Iranian Bandar Anzeli.

(Baku Bay, Baku - a city on the Caspian Sea)

Interesting Facts

Scientists are still arguing about whether to call a reservoir a sea or a lake. The level of the Caspian Sea is gradually decreasing. The Volga delivers most of the water to the Caspian. 90% of black caviar is mined in the Caspian Sea. Among them, the most expensive is Almas beluga caviar ($2,000 per 100 g).

Companies from 21 countries are participating in the development of oil fields in the Caspian Sea. According to Russian estimates, hydrocarbon reserves in the sea amount to 12 billion tons. American scientists claim that one fifth of the world's hydrocarbon reserves are concentrated in the depths of the Caspian Sea. This is more than the combined reserves of such oil-producing countries as Kuwait and Iraq.

Caspian Sea is inland and located in a vast continental depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows it to be called a lake, but it has all the features of the sea, since it had connections with the ocean in past geological epochs.
Today, Russia has access only to the Northern Caspian and the Dagestan part of the western coast of the Middle Caspian. The waters of the Caspian Sea wash the shores of such countries as Azerbaijan, Iran, Turkmenistan, Kazakhstan.
The area of ​​the sea is 386.4 thousand km2, the volume of water is 78 thousand m3.

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

In physical and geographical terms and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional boundary between the northern and middle parts runs along the line of Chechen Island–Cape Tyub-Karagan, between the middle and southern parts - along the line of Zhiloy Island–Cape Kuuli.
The shelf of the Caspian Sea, on average, is limited to depths of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at about 500–600 m, in the southern part, where it is very steep, at 700–750 m.

The northern part of the sea is shallow, its average depth is 5–6 m, the maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom relief is complicated by the presence of banks, islands, furrows.
The middle part of the sea is a separate basin, the region of maximum depths of which - the Derbent depression - is shifted to the western coast. The average depth of this part of the sea is 190 m, the greatest is 788 m.

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

coast The Caspian Sea are diverse. In the northern part of the sea, they are quite strongly indented. Here are the bays of Kizlyar, Agrakhan, Mangyshlak and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy, Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islets and channels, which often change their position. Many small islands and banks are located on other parts of the coastline.
The middle part of the sea has a relatively flat coastline. On the west coast, on the border with southern part seaslocated Absheron Peninsula. To the east of it, the islands and banks of the Apsheron archipelago stand out, of which the most large island Residential. The eastern shore of the Middle Caspian is more indented, the Kazakh Bay stands out here with the Kenderli Bay and several capes. The largest bay of this coast is Kara-Bogaz-Gol.

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

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

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

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

Climate. The Caspian Sea is located in the temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since the sea stretches for almost 1200 km from north to south.
In the Caspian region, various systems of atmospheric circulation interact, however, during the year, easterly winds prevail (the influence of the Asian maximum). The position at rather low latitudes provides a positive balance of heat inflow, so the Caspian Sea serves as a source of heat and moisture for passing air masses for most of the year. The average annual air temperature in the northern part of the sea is 8–10°С, in the middle part - 11–14°С, in the southern part – 15–17°С. However, in the most northern regions sea, the average January temperature is from –7 to –10°С, and the minimum during the intrusions of the Arctic air is up to –30°С, which determines the formation of the ice cover. In summer, rather high temperatures dominate over the entire region under consideration - 24–26°С. Thus, the Northern Caspian is subject to the most sharp temperature fluctuations.

The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, and most of it falls on the cold season of the year (from October to March). However, the Northern Caspian differs in this respect from the rest of the basin: here the average annual precipitation is less (only 137 mm for the western part), and the distribution over the seasons is more even (10–18 mm per month). In general, we can talk about proximity climatic conditions to the arid ones.
Water temperature. The distinctive features of the Caspian Sea (great differences in depths in different parts of the sea, the nature of the bottom relief, isolation) have a certain influence on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be considered as homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and South Caspian, surface and deep masses separated by a transitional layer can be distinguished. In the Northern Caspian and in the surface layers of the Middle and Southern Caspian, the water temperature varies over a wide range. In winter, temperatures vary from north to south from less than 2 to 10°С, the water temperature near the western coast is 1–2°С higher than near the eastern one, in the open sea the temperature is higher than near the coasts: by 2–3°С in the middle part and by 3–4°С in the southern part of the sea. In winter, the temperature distribution is more uniform with depth, which is facilitated by the winter vertical circulation. During moderate and severe winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing.

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

Salinity. Salinity values ​​are determined by such factors as river runoff, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts of the Northern Caspian and between the Northern and Middle Caspian, the bottom topography, which determines the location of waters with different salinity, mainly along the isobaths, evaporation, which ensures the deficit fresh water and the influx of more salty. These factors collectively affect the seasonal differences in salinity.
The Northern Caspian can be considered as a reservoir of constant mixing of river and Caspian waters. The most active mixing occurs in the western part, where both river and Central Caspian waters directly enter. In this case, horizontal salinity gradients can reach 1‰ per 1 km.

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

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

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea waters, with runoff playing a decisive role. The intensification of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated waters coming from the coast in summer is 10–15°C higher than that of the bottom ones.
IN deep sea trenches In the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of ​​the Apsheron threshold, where it is 1.6‰ in the surface layer and 2.1‰ at the 5 m horizon.

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

In addition, salinity increases in the South Caspian due to the removal of saline waters from bays and inlets on the eastern shelf under the action of southeasterly winds. In the future, these waters are transferred to the Middle Caspian.
In the deep layers of the Middle and South Caspian, salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep part of the South Caspian, the upper boundary of waters with increased salinity drops to 250 m. Obviously, in these parts of the sea vertical mixing water is difficult.

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

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

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

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

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

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

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

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

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

For more than 150 years, oil has been mined on the shelf of the Caspian Sea oil.
Currently, large reserves of hydrocarbons are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons of oil equivalent (of which 132 million tons of oil and 78 billion m3 of gas), on the shelf of the Northern Caspian - 1 billion tons of oil .
In total, about 2 billion tons of oil have already been produced in the Caspian.
Losses of oil and products of its processing during extraction, transportation and use reach 2% of the total volume.
Main sources of income pollutants, including oil products, into the Caspian Sea - this is the removal with river runoff, the discharge of untreated industrial and agricultural effluents, domestic wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, oil transportation by sea. 90% of pollutants with river runoff are concentrated in the Northern Caspian, industrial effluents are confined mainly to the area of ​​the Apsheron Peninsula, and increased oil pollution of the Southern Caspian is associated with oil production and oil exploration drilling, as well as active volcanic activity (mud volcanism) in the zone of oil and gas bearing structures.

From the territory of Russia, about 55 thousand tons of oil products enter the Northern Caspian every year, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.
The thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange and threatens the death of hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg/l, for phytoplankton - 0.1 mg/l.

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

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

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

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

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

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

The Caspian Sea provides more than 80% of the world's sturgeon catch, most of which falls on the North Caspian.
To increase the catches of sturgeon, which dropped sharply during the years of sea level drop, a set of measures is being implemented. Among them - a complete ban on sturgeon fishing in the sea and its regulation in rivers, an increase in the scale of factory breeding of sturgeons.

The Caspian Sea is on our planet. Speaking about where it is located, it can be noted that it is located directly between Europe and Asia. It is called the sea just because of its incredible size, because the area of ​​\u200b\u200bthe lake is about 371,000 square meters. km. And also, because the water in it is salty - a little less in the north and a little more in the southern part.

The total length of the coastline of the Caspian Sea is about 7000 km. Holidays on the Caspian Sea are represented by a large selection tourist bases, hotels and hotels located along the coast. In addition, going to rest on the Caspian Sea, you need to decide on the coast of which country you want to spend your vacation. After all, the countries of the Caspian Sea are Kazakhstan, Russia, Turkmenistan, Iran and Azerbaijan. And each of them offers its own unforgettable scenario for your holiday.

On the territory of the Russian Federation, you can go to Astrakhan, Kaspiysk or Makhachkala.

In Kazakhstan, you can visit resorts on the Caspian Sea: Atyrau, Aktau or Kuryk.

Resting in Azerbaijan, you can spend time in beautiful capital Baku or in the cities of Sumgayit, Khachmas, Siyazan, Alyat or Lankaran.

Tourists who decide to visit Turkmen resorts should pay attention to such coastal cities as Begdash, Kualymayak, Turkmenbashi, Cheleken, Okarem or Esenguly.

The southern coast of the Caspian Sea belongs to Iran. Deciding to spend your vacation on the territory of this country, you can go to Lengerud, Nowsherh or Bandar Anzeli.

The volume of water in the sea varies periodically, but on average it contains 44% of all lake water in the world. The greatest depth of the Caspian Sea is 1025 m. This point is located in the South Caspian depression. Thus, in terms of size maximum depth The Caspian Sea is the third lake in the world after Baikal and Tanganyika.

Water temperature

The water temperature of the Caspian Sea depends on the time of year and latitudinal changes. The most striking period for observing the temperature difference is winter. So, on the northern coast of the lake in the cold season, the temperature can reach 0°C, and in the south at the same time about 10–11°C.

By the end of spring, the water in the northern part of the Caspian Sea warms up quickly, reaching 16–17°C. This is due to the shallow depth of the waters of this area. Approximately the same water temperature in the spring and off the southern coast. The depth of the lake here is greater and therefore the water warms up more slowly.

In summer, the climate of the Caspian Sea allows everyone to enjoy their holidays in coastal areas. The hottest month is August. The air during this period warms up to +25°C in the northern regions and up to +28°C in the south. The highest temperature of +44°C was recorded on the eastern coast. The water temperature in the lake in summer is 25°C, and on south coast can reach up to 28°C. In shallow waters and small bays, this figure increases to 32°C.

By autumn, the water cools again, changing to the winter period. In October-November, the water temperature is about 12°C in the north and about 16°C in the south.

A beach holiday on the Caspian Sea can give no less pleasure than a vacation on Black Sea coast. In addition, due to the fact that the Caspian Sea is shallower, the water here warms up much faster and, accordingly, starts earlier. bathing season. And velvety sand and picturesque views will add good impressions beach lovers.

In addition, the lake is popular with fans of fishing. After all, 101 species of fish are registered in the Caspian Sea. Among them are not only carp, bream, salmon or pike, but also such a rarity as beluga.

The Caspian Sea is the largest lake on our planet. It is located between Europe and Asia and is called the sea for its size.

Caspian Sea

The water level is below the level of 28m. The water in the Caspian Sea has less salinity in the north in the delta. The highest salinity is observed in the southern regions.

The Caspian Sea covers an area of ​​371 thousand km2, the greatest depth is 1025 meters (South Caspian depression). The coastline is estimated from 6500 to 6700 km, and if you take it together with the islands, then more than 7000 km.

The seashore is mostly low-lying and smooth. If you look at the northern part, then there are many islands, water channels, indented by the Volga and the Urals. In these places, the coast is swampy and covered with thickets. From the east, semi-desert and desert terrain with limestone shores approaches the sea. The area of ​​the Kazakh Bay, the Absheron Peninsula and the Kara-Bogaz-Gol Bay have winding shores.

Bottom relief

The bottom relief is divided into three main forms. Shelf in the northern part, the average depth here is from 4 to 9 m, the maximum is 24 m, which gradually increases and reaches 100 m. The continental slope in the middle part drops to 500 m. northern part the Mangyshlak threshold separates from the middle one. Here is one of the most deep places Derbent depression (788 m).

2. Heraz, Babol, Sefudrud, Gorgan, Polerud, Chalus, Tejen - https://site/russia/travel/po-dagestanu.html;

4. Atrek - Turkmenistan;

Samur is located on the border between Azerbaijan and Russia, Astarachay is on the border of Azerbaijan and Iran.

The Caspian Sea belongs to five states. From the west and northwest, the length of the coast of 695 km is the territory of Russia. Most of the coastline with a length of 2320 km belongs to Kazakhstan in the east and northeast. Turkmenistan has 1,200 km in the southeast, Iran has 724 km in the south, and Azerbaijan has 955 km of coastline in the southwest.

In addition to the five states that have access to the sea, the Caspian basin also includes Armenia, Turkey, and Georgia. The Volga (Volga-Baltic Way, White Sea-Baltic Canal) connects the sea with the World Ocean. There is a connection with the Azov and Black Seas through the Volga-Don Canal, with the Moscow River (the Moscow Canal).

The main ports are Baku in Azerbaijan; Makhachkala in ; Aktau in Kazakhstan; Olya in Russia; Nowshahr, Bander-Torkemen and Anzeli in Iran.

The largest bays of the Caspian Sea: Agrakhan, Kizlyar, Kaydak, Kazakh, Dead Kultuk, Mangyshlak, Hasan-kuli, Turkmenbashi, Kazakh, Gyzlar, Enzeli, Astrakhan, Gyzlar.

Until 1980, Kara-Bogaz-Gol was a bay-lagoon, which was connected to the sea by a narrow strait. Now it is a salt lake, separated from the sea by a dam. After the construction of the dam, the water began to decrease sharply, and a culvert had to be built. Through it, up to 25 km3 of water enters the lake annually.

Water temperature

The greatest fluctuations in temperature are observed in winter. In shallow water, it reaches 100 in winter. The difference between summer and winter temperatures reaches 240. On the coast in winter, it is always 2 degrees lower than in the open sea. The optimum warming up of the water occurs in July-August, in shallow water the temperature reaches 320. But at this time, north-western winds raise cold layers of water (upwelling). This process begins already in June and reaches intensity in August. The temperature at the surface of the water drops. The temperature difference between the layers disappears by November.

The climate in the northern part of the sea is continental, in the middle part it is temperate, and in the southern part it is subtropical. On the east coast, the temperature is always higher than on the west. Once on the east coast recorded 44 degrees.

The composition of the Caspian waters

About salinity is 0.3%. This is a typical desalinated pool. But the farther south, the higher the salinity. In the southern part of the sea, it already reaches 13%, and in Kara-Bogaz-Gol more than 300%.

Storms are frequent in shallow water areas. They occur due to changes in atmospheric pressure. Waves can reach 4 meters.

The water balance of the sea depends on river flows and precipitation. Among them, the Volga makes up almost 80% of all other rivers.

IN last years there is a rapid pollution of water by oil products and phenols. Their level already exceeds the permissible level.

Minerals

Back in the 19th century, the beginning of hydrocarbon production was laid. These are the main natural resources. There are also mineral, balneological biological resources. Today, in addition to gas and oil production, salts are mined on the shelf marine type(astrakhanite, mirabalite, halite), sand, limestone, clay.

Animal and plant world

The fauna of the Caspian Sea is up to 1800 species. Of these, 415 are vertebrates, 101 species of fish, and there is a world stock of sturgeons. Freshwater fish such as carp, pike perch, and vobla also live here. They catch carp, salmon, pike, bream in the sea. The Caspian Sea is the habitat of one of the mammals - the seal.

From plants, blue-green algae, brown, red can be noted. Zostera and ruppia also grow, they are classified as flowering algae.

The plankton brought into the sea by birds begins to bloom in spring, the sea is literally covered with greenery, and rhizosolation during flowering paints most of the sea territory in yellow-green color. The accumulation of rhizosolenia is so dense that even waves can calm down. In some places near the coast, literally meadows of algae have grown.

On the coast you can see both local and migratory birds. In the south, geese, ducks winter, birds such as pelicans, herons, flamingos arrange nesting.

The Caspian Sea contains almost 90% of the world's sturgeon stocks. But recently, the environment has been deteriorating, you can often meet poachers who hunt sturgeon because of expensive caviar.

Governments are investing a lot of money to improve the situation. They purify sewage, build factories for breeding fish, despite these measures, it is necessary to limit the production of sturgeon.