Caspian Sea ~ Seas and Oceans. Temperature and salinity. Vertical mixing of waters What is the maximum depth of the Caspian Sea

On Sunday, August 12, in Aktau, Kazakhstan, the presidents of Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan signed the Convention on legal status Caspian Sea. Previously, its status was regulated by Soviet-Iranian treaties, in which the Caspian Sea was defined as a closed (inland) sea, and each Caspian state had sovereign rights to a 10-mile zone and equal rights to the rest of the sea.

Now, according to the new convention, each country is assigned its own territorial waters (zones 15 miles wide). In addition, the provisions of the 1982 UN Convention on the Law of the Sea will not apply to the Caspian Sea, the seabed will be delimited into sectors, as is done by neighboring seas, and sovereignty over the water column will be established on the basis of the principle that it is a lake.

Why is the Caspian considered neither a lake nor a sea?

To be considered a sea, the Caspian Sea must have access to the ocean; this is one of the most important conditions for which a body of water can be called a sea. But the Caspian Sea has no access to the ocean, so it is considered a closed body of water not connected to the World Ocean.

The second feature that distinguishes sea waters from lake waters is their high salinity. The water in the Caspian Sea is indeed salty, but in its salt composition it occupies an intermediate position between the river and the ocean. In addition, in the Caspian Sea, salinity increases towards the south. The Volga delta contains 0.3‰ salts, and in the eastern regions of the Southern and Middle Caspian Sea the salinity reaches 13-14‰. And if we talk about the salinity of the World Ocean, it averages 34.7 ‰.

Due to its specific geographical and hydrological characteristics, the reservoir received a special legal status. The summit participants decided that the Caspian Sea is an inland body of water that does not have a direct connection with the World Ocean, and therefore cannot be considered a sea, and at the same time, due to its size, water composition and bottom features, cannot be considered a lake.

What has been achieved since the signing of the Convention?

The new treaty expands opportunities for cooperation between countries and also involves limiting any military presence of third countries. According to political scientist, director of the Institute of Modern States Alexey Martynov, the main achievement of the last summit is that its participants managed to stop any talk about the possible construction of military bases and NATO infrastructure facilities in the Caspian Sea.

“The most important thing that was achieved was to fix that the Caspian Sea will be demilitarized for all Caspian states. There will be no other military personnel there except those representing the countries that signed the Caspian Agreement. This is a fundamental and main question that was important to fix. Everything else, what is divided proportionally into zones of influence, zones of extraction of biological resources, zones of extraction of shelf resources, was not so important. As we remember, in the last twenty years the military has been actively seeking to enter the region. The USA even wanted to build their own there military base“says Martynov.

In addition to the distribution of each country's shares in the oil and gas fields of the Caspian basin, the Convention also provides for the construction of pipelines. As stated in the document, the rules for laying them provide for the consent of only neighboring countries, and not all countries of the Caspian Sea. After signing the agreement, Turkmenistan, in particular, stated that it was ready to lay pipelines along the bottom of the Caspian Sea, which would allow it to export its gas through Azerbaijan to Europe. The consent of Russia, which previously insisted that the project could only be implemented with the permission of all five Caspian states, is now no longer required. They plan to subsequently connect the gas pipeline to the Trans-Anatolian gas pipeline, through which natural gas will flow through the territory of Azerbaijan, Georgia and Turkey to Greece.

“Turkmenistan is not a foreign country to us, but our partner, a country that we consider very important for us in the post-Soviet space. We cannot be against them receiving an additional impetus for development through such pipeline projects. Gas has long been coming from Turkmenistan and other countries through another pipeline system, somewhere it is even mixed with Russian gas, and there is nothing wrong with that. If this project works, everyone will benefit, including Russia. Under no circumstances should the project be considered as some kind of competition. The European market is so large and insatiable, I mean the energy market, that there is enough room for everyone,” says Martynov.

Today, almost all Turkmen gas is supplied to China, where Russia also intends to supply blue fuel. For this purpose, in particular, a large-scale project for the construction of the Power of Siberia gas pipeline is being implemented. Thus, the geography of gas supplies for both countries can expand - Turkmenistan will gain access to the European market, and Russia will be able to increase its gas supplies to China.

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42° N. w. 51° east d. HGIOL

Caspian Sea- the largest closed body of water on Earth, which can be classified as the largest endorheic lake, or as a full-fledged sea, due to its size, and also due to the fact that its bed is folded earth's crust oceanic type. Located at the junction of Europe and Asia. The water in the Caspian Sea is brackish, from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data it was 27.16 m below sea level. The area of ​​the Caspian Sea is currently approximately 371,000 km², the maximum depth is 1025 m.

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Etymology

Geographical position

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

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

Coast

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

Peninsulas

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

Islands

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

Largest islands:

Bays

Large bays:

Kara-Bogaz-Gol

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

Rivers flowing into the Caspian Sea

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

Basin of the Caspian Sea

Coastal states

According to the Intergovernmental Economic Conference of the Caspian States:

The Caspian Sea washes the shores of five coastal states:

Cities on the Caspian Sea coast

On the Russian coast there are cities - Lagan, Makhachkala, Kaspiysk, Izberbash, Dagestan Lights and the most Southern City Russia Derbent. Astrakhan is also considered a port city of the Caspian Sea, which, however, is not located on the shores of the Caspian Sea, but in the Volga delta, 60 kilometers from the northern coast of the Caspian Sea.

Physiography

Area, depth, volume of water

The area and volume of water in the Caspian Sea varies significantly depending on fluctuations in water levels. At a water level of −26.75 m, the area is approximately 371,000 square kilometers, the volume of water is 78,648 cubic kilometers, which is approximately 44% of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface level. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated from the bathygraphic curve, is 208 meters. In the same time Northern part The Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. 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, however, some plants were brought into the Caspian Sea by humans deliberately, or on the bottoms of ships.

Story

Origin

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

The deep long-term Atelian regression of the mid-Late Pleistocene at the initial stage had a level of −20 - −25 m, at the maximum stage −100 - −120 m, at the third stage - −45 - −50 m. At the maximum, the basin area is reduced to 228 thousand km² . After Atel regression (−120 - −140 m), approx. 17 thousand l. n. The early Khvalynian transgression began - up to + 50 m (the Manych-Kerch Strait was functioning), which was interrupted by the Eltonian regression. The Early Khvalyn II basin (level up to 50 m) was replaced at the beginning of the Holocene by a short-term Enotaev regression (from −45 to −110 m), coinciding in time with the end of the Preboreal and the beginning of the Boreal. The Enotayevskaya regression gave way to the Late Khvalynskaya transgression (0 m). The Late Khvalynian transgression was replaced in the Holocene (ca. 9-7 thousand years ago or 7.2-6.4 thousand years ago) by the Mangyshlak regression (from −50 to −90 m). The Mangyshlak regression gave way during the first phase of interglacial cooling and humidification (Atlantic period) to the New Caspian transgression. The New Caspian basin was brackish-water (11-13 ‰), warm-water and isolated (level up to −19 m). At least three cycles of transgressive-regressive phases have been recorded in the development of the Novo-Caspian basin. The Dagestan (Gousan) transgression previously belonged to the initial stage of the New Caspian era, but the absence of a leading New Caspian form in its sediments Cerastoderma glaucum (Cardium edule) gives grounds for identifying it as an independent transgression of the Caspian Sea. The Izberbash regression, separating the Dagestan and the Neo-Caspian transgressions of the Caspian Sea itself, occurred between 4.3 and 3.9 thousand years ago. Judging by the structure of the Turali section (Dagestan) and radiocarbon analysis data, transgressions were noted twice - about 1900 and 1700 years ago.

Anthropological and cultural history of the Caspian Sea

Shipping

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

Fishing and seafood production

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

Recreational resources

Natural environment of the Caspian coast with sandy beaches, mineral waters and healing mud in the coastal zone creates good conditions for relaxation and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast is noticeably inferior to the Black Sea coast of the Caucasus. At the same time, in last years The tourism industry is actively developing on the coasts of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. Azerbaijan is actively developing resort area in the Baku region. A world-class resort has now been created in Amburan, another modern tourist complex is being built in the area of ​​the village of Nardaran, holidays in the sanatoriums of the villages of Bilgah and Zagulba are very popular. A resort area is also being developed in Nabran, in northern Azerbaijan. However high prices, in general, the low level of service and lack of advertising lead to the fact that Caspian resorts almost no foreign tourists. The development of the tourism industry in Turkmenistan is hampered by a long-term policy of isolation; in Iran, Sharia law, due to which mass recreation foreign tourists on the Caspian coast of Iran is impossible.

Ecological problems

Environmental problems of the Caspian Sea are associated with water pollution as a result of oil production and transportation on the continental shelf, the flow of pollutants from the Volga and other rivers flowing into the Caspian Sea, the life activity of coastal cities, as well as the flooding of individual objects due to rising levels of the Caspian Sea. Predatory production of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeon and to forced restrictions on their production and export.

Legal status

After the collapse of the USSR, the division of the Caspian Sea has long been and still remains the subject of unresolved disagreements related to the division of Caspian shelf resources - oil and gas, as well as biological resources. For a long time, negotiations were ongoing between the Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran insisted on dividing the Caspian by one-fifth between all Caspian states.

In relation to the Caspian Sea, the key is the physical-geographical circumstance that it is a closed inland body of water that does not have a natural connection with the World Ocean. Accordingly, the norms and concepts of international maritime law, in particular, the provisions of the 1982 UN Convention on the Law of the Sea, should not automatically apply to the Caspian Sea. Based on this, in relation to the Caspian Sea it would be unlawful to apply such concepts as “territorial sea”, “exclusive economic zone”, “continental shelf”, etc.

The current legal regime of the Caspian Sea was established by the Soviet-Iranian treaties of 1921 and 1940. These treaties provide for freedom of navigation throughout the sea, freedom of fishing with the exception of ten-mile national fishing zones and a ban on vessels flying the flag of non-Caspian states sailing in its waters.

Negotiations on the legal status of the Caspian Sea are currently ongoing.

Delineation of sections of the Caspian seabed for subsoil use

The Russian Federation concluded an agreement with Kazakhstan on delimiting the bottom of the northern part of the Caspian Sea in order to exercise sovereign rights to subsoil use (dated July 6, 1998 and the Protocol thereto dated May 13, 2002), an agreement with Azerbaijan on delimiting adjacent areas of the bottom of the northern part of the Caspian Sea (dated September 23, 2002), as well as the trilateral Russian-Azerbaijani-Kazakh agreement on the junction point of the demarcation lines of adjacent sections of the Caspian Sea bottom (dated May 14, 2003), which established geographical coordinates dividing lines limiting the areas of the seabed within which the parties exercise their sovereign rights in the field of exploration and production of mineral resources.

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

The Caspian Sea is 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 Seas passes along the Chechen line (island)- Tyub-Karagansky Cape, between the Middle and Southern Caspian Seas - along the Zhilaya line (island)- Gan-Gulu (Cape). The area of ​​the Northern, Middle and Southern Caspian Sea is 25, 36, 39 percent, respectively.

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

The coastline of the Caspian Sea is estimated at approximately 6,500 - 6,700 kilometers, with islands - up to 7,000 kilometers. The shores of the Caspian Sea in most of its territory are low-lying and smooth. In the northern part, the coastline is indented by water streams and islands of the Volga and Ural deltas, the 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.

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

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

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

On the eastern coast is the salt lake Kara Bogaz Gol, which until 1980 was a bay-lagoon of the Caspian Sea, connected to it by a narrow strait. In 1980, a dam was built separating Kara-Bogaz-Gol from the Caspian Sea, and in 1984 a culvert was built, after which the level of Kara-Bogaz-Gol dropped by several meters. In 1992, the strait was restored, through which water flows from the Caspian Sea to Kara-Bogaz-Gol and evaporates there. Every year, 8 - 10 cubic kilometers of water flow from the Caspian Sea to Kara-Bogaz-Gol (according to other sources - 25 thousand kilometers) and about 150 thousand tons of salt.

130 rivers flow into the Caspian Sea, of which 9 rivers have a delta-shaped mouth. Large rivers flowing into the Caspian Sea - Volga, Terek (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Samur (Russian border with Azerbaijan), Atrek (Turkmenistan) and others. The largest river flowing into the Caspian Sea is the Volga, its average annual flow is 215-224 cubic kilometers. The Volga, Ural, Terek and Emba provide up to 88 - 90% of the annual runoff of the Caspian Sea.

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

The Caspian Sea washes the shores of five coastal states:

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

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

Large Russian cities - the capital of Dagestan, Makhachkala, and the southernmost city of Russia, Derbent - are located on the western coast of the Caspian Sea. Astrakhan is also considered a port city of the Caspian Sea, which, however, is not located on the shores of the Caspian Sea, but in the Volga delta, 60 kilometers from the northern coast of the Caspian Sea.

On east coast On the Caspian Sea there is a Kazakh city - the port of Aktau, in the north in the Ural delta, 20 km from the sea, the city of Atyrau is located, south of Kara-Bogaz-Gol on the northern shore of the Krasnovodsk Bay - the Turkmen city of Turkmenbashi, former Krasnovodsk. Several Caspian cities are located in the southern (Iranian) coast, the largest of them is Anzeli.

The area and volume of water of the Caspian Sea varies significantly depending on fluctuations in water levels. At a water level of −26.75 m, the area was approximately 392,600 square kilometers, the volume of water was 78,648 cubic kilometers, which is approximately 44 percent of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface level. In terms of maximum depth, the Caspian Sea is second only to Lake Baikal (1620 m.) and Tanganyika (1435 m.). The average depth of the Caspian Sea, calculated from the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

The water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past 3 thousand years the amplitude of changes in the water level of the Caspian Sea has been 15 meters. Instrumental measurements of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out since 1837, during which time the highest water level was recorded in 1882 (-25.2 m.), lowest - in 1977 (-29.0 m.), since 1978 the water level has risen and in 1995 reached −26.7 m; since 1996, a downward trend has emerged again. Scientists associate the reasons for changes in the water level of the Caspian Sea with climatic, geological and anthropogenic factors.

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 difference in water temperature 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 is west coast 1 - 2 °C higher than in the east, and in the open sea the water temperature is 2 - 4 °C higher than on the coasts. Based on the nature of the horizontal structure of the temperature field in the annual cycle of variability, three time periods can be distinguished in the upper 2-meter layer. From October to March, the water temperature increases in the southern and eastern regions, which is especially clearly visible in the Middle Caspian. Two stable quasi-latitudinal zones can be distinguished, where temperature gradients are increased. This is, firstly, the border between the Northern and Middle Caspian, and, secondly, between the Middle and Southern. At the ice edge, in the northern frontal zone, the temperature in February-March increases from 0 to 5 °C, in the southern frontal zone, in the area of ​​the Absheron threshold, from 7 to 10 °C. During this period, the least cooled waters are in the center of the South Caspian Sea, which form a quasi-stationary core. In April-May, the area of ​​minimum temperatures moves to the Middle Caspian Sea, which is associated with faster heating of waters in the shallow northern part of the sea. True, at the beginning of the season in the northern part of the sea a large number of heat is spent on melting the ice, but already in May the temperature here rises to 16 - 17 °C. In the middle part the temperature at this time is 13 - 15 °C, and in the south it increases to 17 - 18 °C. Spring warming of water evens out horizontal gradients, and the temperature difference between coastal areas and open sea does not exceed 0.5 °C. Warming of the surface layer, which begins in March, disrupts the uniformity of temperature distribution with depth. In June-September, horizontal uniformity in the temperature distribution in the surface layer is observed. In August, which is the month of greatest warming, the water temperature throughout the sea is 24 - 26 °C, and in the southern regions it rises to 28 °C. In August, the water temperature in shallow bays, for example, in Krasnovodsk, can reach 32 °C. The main feature of the water temperature field at this time is upwelling. It is observed annually along the entire eastern coast of the Middle Caspian and partially penetrates even into the Southern Caspian. The rise of cold deep waters occurs with varying intensity as a result of the influence of prevailing summer season northwest winds. The wind in this direction causes the outflow of warm surface waters from the coast and the rise of colder waters from the intermediate layers. Upwelling begins in June, but it reaches its greatest intensity in July-August. As a result, a decrease in temperature is observed on the water surface (7 - 15 °C). Horizontal temperature gradients reach 2.3 °C on the surface and 4.2 °C at a depth of 20 m. The source of upwelling gradually shifts from 41 - 42° N. in June to 43 - 45° N. in September. Summer upwelling is of great importance for the Caspian Sea, radically changing the dynamic processes in the deep-water area. In open areas of the sea, at the end of May - beginning of June, the formation of a temperature jump layer begins, which is most clearly expressed in August. Most often it is located between horizons of 20 and 30 m in the middle part of the sea and 30 and 40 m in the southern part. Vertical temperature gradients in the shock layer are very significant and can reach several degrees per meter. In the middle part of the sea, due to the surge off the eastern coast, the shock layer rises close to the surface. Since in the Caspian Sea there is no stable baroclinic layer with a large reserve of potential energy similar to the main thermocline of the World Ocean, then with the cessation of the prevailing winds causing upwelling and with the beginning of autumn-winter convection in October-November, a rapid restructuring of temperature fields to the winter regime occurs. In the open sea, the water temperature in the surface layer drops in the middle part to 12 - 13 °C, in the southern part to 16 - 17 °C. In the vertical structure, the shock layer is eroded due to convective mixing and disappears by the end of November.

The salt composition of the waters of the closed Caspian Sea differs from the oceanic one. There are significant differences in the ratios of concentrations of salt-forming ions, especially for waters in areas directly influenced by continental runoff. The process of metamorphization of sea waters under the influence of continental runoff leads to a decrease in the relative content of chlorides in the total amount of salts of sea waters, an increase in the relative amount of carbonates, sulfates, calcium, which are the main components in chemical composition river waters. The most conservative ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ions. In the Caspian Sea, the content of calcium and magnesium cations is almost two times higher than in the Sea of ​​Azov, and the sulfate anion is three times higher. Water salinity changes especially sharply in the northern part of the sea: from 0.1 units. psu in the mouth areas of the Volga and Ural up to 10 - 11 units. psu on the border with the Middle Caspian. Mineralization in shallow salty bays-kultuks can reach 60 - 100 g/kg. In the Northern Caspian, during the entire ice-free period from April to November, a salinity front of a quasi-latitudinal location is observed. The greatest desalination, associated with the spread of river flow across the sea, is observed in June. The formation of the salinity field in the Northern Caspian Sea is greatly influenced by the wind field. In the middle and southern parts of the sea, salinity fluctuations are small. Basically it is 11.2 - 12.8 units. psu, increasing in the southern and eastern directions. Salinity increases slightly with depth (by 0.1 - 0.2 psu units). In the deep-sea part of the Caspian Sea, in the vertical profile of salinity, characteristic deflections of isohalines and local extrema are observed in the area of ​​the eastern continental slope, which indicate the processes of bottom sliding of waters salinizing in the eastern shallow waters of the South Caspian. The salinity value also strongly depends on sea level and (which is related) on the volume of continental runoff.

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 about 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.

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

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

Winds often blow on the territory of the Caspian Sea, their average annual speed is 3-7 meters per second, the wind rose is dominated by north winds. In the autumn and winter months, winds become stronger, with wind speeds often reaching 35-40 meters per second. The most windy territories are the Absheron Peninsula and the environs of Makhachkala - Derbent, where the most high wave- 11 meters.

Water circulation in the Caspian Sea is related to runoff and winds. Since most of the drainage occurs in the Northern Caspian Sea, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current divides into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

The fauna of the Caspian Sea is represented by 1810 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian world, where most of the world's sturgeon reserves 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. Since March 31, 2008, 363 dead seals have been found on the coast of the Caspian Sea in Kazakhstan.

The flora of the Caspian Sea and its coast is represented by 728 species. Among the plants in the Caspian Sea, the predominant algae are blue-green, diatoms, red, brown, characeae and others, and among the 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.

The 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 in past geological eras it had connections with the ocean.

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

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

Physiographically and by nature, the sea is divided into three parts: northern, middle and southern. The conventional border between the northern and middle parts runs along the line Chechen Island–Cape Tyub-Karagan, and between the middle and southern parts along the line Zhiloy Island–Cape Kuuli.

The shelf of the Caspian Sea is on average limited to depths of about 100 m. The continental slope, which begins below the shelf edge, ends in the middle part at approximately 500–600 m depths, 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 topography is complicated by the presence of banks, islands, and grooves.

The middle part of the sea is an isolated basin, the region of maximum depths of which - Derbent - is shifted to the western shore. 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 by the Absheron threshold, which is a continuation. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum sea depth of 1025 m is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.

The shores of the Caspian Sea are diverse. In the northern part of the sea they are quite indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy and Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islands and channels, often changing 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. The Absheron Peninsula is located on the western coast, on the border with the southern part of the sea. To the east of it there are islands and banks of the Absheron archipelago, of which the largest island is Zhiloy. The eastern coast of the Middle Caspian is more indented; the Kazakh Gulf with Kenderli Bay and several capes stand out here. The largest bay of this coast is.

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 on the bottom of the sea. On the eastern shore there are large bays of Turkmenbashi and Turkmensky, and near it 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 level lower than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) of sea level, the amplitude of its fluctuations has been almost 4 m, from –25.3 m in the eighties of the 19th century. to –29 m in 1977. In the last century, the level of the Caspian Sea changed significantly twice. In 1929 it stood at about -26 m, and since it had been close to this level for almost a century, this level position was considered to be a long-term or secular average. In 1930 the level began to decline rapidly. By 1941 it had dropped by almost 2 m. This led to the drying out of vast coastal areas of the bottom. The decrease in level, with slight fluctuations (short-term slight rises in level in 1946–1948 and 1956–1958), continued until 1977 and reached a level of –29.02 m, i.e. the level reached its lowest position in history the last 200 years.

In 1978, contrary to all forecasts, sea level began to rise. As of 1994, the level of the Caspian Sea was at –26.5 m, that is, over 16 years the level rose by more than 2 m. The rate of this rise is 15 cm per year. The level increase 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 long-term average of which reaches 40 cm, as well as surge phenomena. The latter are especially pronounced in the Northern Caspian Sea. The northwestern coast is characterized by large surges created by prevailing storms from the eastern and southeastern directions, especially in the cold season. A number of large (more than 1.5–3 m) surges have been observed here over the past decades. 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 waters.

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

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

The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, with most of it falling during 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 lower (for the western part only 137 mm), and the seasonal distribution is more uniform (10–18 mm per month). In general, we can talk about proximity to arid ones.

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

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 Northern Caspian Sea. The zone where the lowest temperatures occur is adjacent to the east coast. This is explained by the rise of cold deep waters to the surface. Temperatures are also relatively low in the poorly heated deep-sea central part. In open areas of the sea, at the end of May–beginning of June, the formation of a temperature jump layer begins, which is most clearly expressed in August. Most often it is located between 20 and 30 m in the middle part of the sea and 30 and 40 m in the southern part. In the middle part of the sea, due to the surge off the eastern coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature throughout the year is about 4.5°C in the middle part and 5.8–5.9°C in the southern part.

Salinity. Salinity values ​​are determined by factors such 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, bottom topography, which determines the location of waters with different, mainly along isobath, evaporation, providing a deficit of fresh water and an influx of saltier water. These factors collectively influence seasonal differences in salinity.

The Northern Caspian can be seen as a constant mixture of river and Caspian waters. The most active mixing occurs in the western part, where both river and Central Caspian waters directly flow. Horizontal salinity gradients can reach 1‰ per 1 km.

The eastern part of the Northern Caspian Sea 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.

Based on the values ​​of horizontal salinity gradients, it is possible to distinguish in the western part of the Northern Caspian the river-sea contact zone with water salinity from 2 to 10‰, in the eastern part from 2 to 6‰.

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea waters, with runoff playing a decisive role. The strengthening 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 seashore in summer is 10–15°C higher than the bottom waters.

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

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

In addition, in the Southern Caspian Sea, an increase in salinity occurs when salted waters are carried out from bays and bays on the eastern shelf under the influence of southeastern winds. Subsequently, these waters are transferred to the Middle Caspian Sea.

In the deep layers of the Middle and Southern Caspian Sea, the salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep-water part of the Southern Caspian, the upper boundary of waters with high salinity drops to 250 m. Obviously, in these parts of the sea, vertical mixing of waters 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 part - southwestern and southern ones. Currents caused by the runoff of the Volga and Ural rivers can be traced only within the estuary coastal area. The prevailing current speeds are 10–15 cm/s, in open areas of the Northern Caspian Sea the maximum speeds are about 30 cm/s.

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

Ice formation. The Northern Caspian Sea is covered with ice every year in November, the area of ​​the frozen part of the water area depends on the severity of the winter: in severe winters the entire Northern Caspian Sea is covered with ice, in mild winters the ice remains within 2–3 meter isobath. The appearance of ice in the middle and southern parts of the sea occurs in December-January. On the eastern coast the ice is of local origin, on the western coast it is 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, shores and fast ice form off the coast, and on the western coast, drifting ice spreads to the Absheron Peninsula in abnormally cold winters. The disappearance of ice cover is observed in the second half of February–March.

Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of patterns.
The central part of the waters of the Northern Caspian Sea is characterized by a fairly uniform distribution of oxygen. An increased oxygen content is found in the areas near the Volga River near the mouth, while a decreased oxygen content is found in the southwestern part of the Northern Caspian Sea.

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

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

The seasonal distribution of oxygen is mainly associated with the annual course and seasonal relationship of production-destruction processes occurring in the sea.

In spring, the production of oxygen during photosynthesis very significantly covers the decrease in oxygen caused by a decrease in its solubility with increasing water temperature in spring.

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

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

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

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

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

• Increased concentrations of nutrients are characteristic of areas near the mouth of coastal rivers that feed the sea and shallow areas of the sea that are subject to active anthropogenic influence(Baku Bay, Turkmenbashi Bay, water areas adjacent to Makhachkala, Fort Shevchenko, etc.);
• The Northern Caspian, which is a vast mixing zone of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
• in the Middle Caspian, the nature of the circulation contributes to the rise of deep waters with a high content of nutrients into the overlying layers of the sea;
• in the deep-water regions of the Middle and Southern Caspian Sea, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.

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

In winter, a significant area of ​​the Northern Caspian Sea is covered with ice, but biochemical processes actively develop in subglacial water and in ice. The ice of the Northern Caspian, being a kind of accumulator of nutrients, transforms these substances entering the sea from and from the atmosphere.

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

Spring for the waters of the Northern Caspian Sea 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 large areas of the Northern Caspian Sea during floods, are due to intensive leaching river waters.

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

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

IN summer time in the waters of the Northern Caspian, a redistribution of various forms of biogenic compounds is detected. Here the content of ammonium nitrogen and nitrates decreases significantly, 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 Southern Caspian Sea, the concentration of phosphates has decreased due to their consumption during photosynthesis and the difficulty of water exchange with the deep-sea accumulation zone.

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

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

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

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

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

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

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

Thickening of the film on the water surface to 0.01 mm disrupts gas exchange processes and threatens the death of hydrobiota. The concentration of petroleum products is toxic to fish at 0.01 mg/l and to phytoplankton at 0.1 mg/l.

The development of oil and gas resources on the bottom of the Caspian Sea, the forecast reserves of which are estimated at 12–15 billion tons of standard fuel, will become the main factor in the anthropogenic load on the sea ecosystem 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 species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire Caspian fauna (mysids, sea cockroach, white fish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna are crustaceans (71.4%), which easily tolerate desalination and live on great depths The Middle and Southern Caspian Sea (from 200 to 700 m), since the lowest water temperatures are maintained here throughout the year (4.9–5.9 ° C).

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

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

Marine species. These are ciliates (386 forms), 2 species of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalves (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 bodies of water on the planet.

The Caspian Sea produces more than 80% of the world's sturgeon catches, the bulk of which occur in the Northern Caspian Sea.

To increase sturgeon catches, which sharply decreased during the years of falling sea levels, a set of measures is being implemented. Among them are a complete ban on sturgeon fishing in the sea and its regulation in rivers, and an increase in sturgeon factory farming.

One of the brightest bodies of water in the world is Caspian lake, which is located at the junction of Asia and Europe, and its shores and waters belong to 5 countries. The Caspian Sea is an attractive and inexpensive place for recreation and treatment. Beautiful nature and the early opening of the swimming seasons make holidays on the Caspian coast more tempting.

The Caspian Lake is the largest of all lakes on the planet. It is often called the Caspian Sea because of its impressive dimensions and slightly salty water. It is located at the junction of Asia and Europe on the territory of 5 countries: Turkmenistan, Kazakhstan, the Russian Federation of Azerbaijan and Iran.

Despite the fact that the tourism infrastructure is inferior in level of development to the Black Sea, the Caspian coast is in demand among tourists. This is facilitated by the rapid warming of the reservoir due to its shallow depth; often the swimming season can begin at the end of April and end in October. The average water temperature in summer is 20-22 °C.

Advantages of holidays on the Caspian Lake:

• clean sea sand;
• picturesque nature;
• sea ​​healing climate;
• mineral springs;
• healing mud;
• the presence of sanatoriums of various orientations;
• excellent fishing, especially in Astrakhan;
• active entertainment for every taste (diving, rafting, windsurfing, etc.);
• low cost of housing and entertainment with developed infrastructure;
• being located on the territory of the Russian Federation, which saves a lot of time on paperwork;
• great service;
• warm water for six months;
• the opportunity to save thousands of rubles on vacation, housing and food without denying yourself anything.

You can get to the Caspian Sea in different ways, but it’s worth deciding in the area of ​​which coastal city to plan your vacation.

In the Russian Federation on the Caspian Lake there are several resort towns:

Astrakhan is very popular among fishermen and amateurs active rest associated with water, because in its vicinity there are many rivers, and the Caspian Lake is just an hour away by car.

Ancient city Derbent also enjoys special love among tourists, because it is surrounded by such attractions as picturesque mountains, ancient fossils and legendary caves, overgrown with legends, and other interesting places to visit.

Such Dagestan resort cities as Izberbash, Kaspiysk, Makhachkala and Kalmyk Lagan are not deprived of attention. Many tourists come to the Caspian Lake and stay in Azerbaijani cities (Baku, Lankaran, Sumgait), Turkmen resorts Turkmentbashi and Avaza, Kazakh Aktau and Atyrau.

Origin of the Caspian Lake and its name

Over 5 million years ago, the ancient sea was divided into several smaller ones, including the Caspian and Black Sea. After this separation, the reservoirs repeatedly merged into one whole and were split up, but approximately 1.75-2 million years ago the reservoir was finally cut off from the waters of the World Ocean.

The modern name of the Caspian Lake is new. And according to one hypothesis, it came from the name of the Caspian tribe, who lived in its southwest in the first millennium BC.

Throughout the entire period of its existence, the Caspian Lake had more than 70 different names among various tribal peoples, including:

1. Abeskunskoe - after the name of the island and the city, which were located before their flooding by a reservoir in the 14th century in a low-lying plain formed by the Kura Kura River.
2. Saraiskoe.
3. Khazar or Mazandaran - an Iranian name in honor of the province of the same name of the country, located on the coast, is used in Iran to this day.
4. Dzhurdzhansky (Hirkansky) - the ancient Greek name of the reservoir, comes from the region of Hyrcania and the city of Gorgan, now belonging to Iran.
5. Derbentskoye is named after the ancient coastal town of the same name in Dagestan.
6. Sihai.
7. Khvaliyskoye is an ancient Russian name, derived from the name of the Khvalis people who lived in the north of the Caspian Sea.

Study and development of the Caspian Lake

Finds on the western coast of Dagestan indicate that people lived in this territory already 2 million ago. At the confluence of the river. Darvagchay (Dagestan) remains have been excavated at sites older than 600 thousand years. Excavations at south coast indicate human habitation in this territory 75 thousand years ago. All these studies show that the climate and living conditions were suitable for humans.

The founder of geography and writer Hecataeus of Miletus (VI-V centuries BC) in his work “Description of the Earth” described the Caspian Sea as the Hyrcanian Sea. In the 5th century BC, the ancient Greek historian was one of the first to suggest that the Caspian is not connected with other seas or oceans, although scientists of those times argued that the reservoir was the northern bay of the World Ocean, which washed all known lands.

Aristotle in the 4th century BC was sure that the Hyrcanian reservoir was connected with the Black Sea by underground waters. Macedonsky studied the relationship of the Caspian Sea with other large bodies of water throughout his travels. In 323 BC, he sent the sailor and geographer Patroclus to explore the shores of the Caspian Sea.

The navigator reached the Kara-Bogaz Bay and considered it a river that connects the Caspian Lake with the ocean. The famous ancient Greek geographer and historian Strabo, in one of his 17 chronicles (books) “Geography”, represented the Caspian Lake stretched in the east-west direction.

Arab scientists of the 9th-13th centuries made a significant contribution to the study of the Caspian Sea, recording in their works information about coastal cities and states, islands, flowing rivers and oil that was produced in Azerbaijan (Baku).

The expansion of the geography of trade relations made it possible for European, Persian and Turkish travelers to receive a lot of information about the Caspian Sea. And the famous Marco Polo (XIII century) also described a huge reservoir.

A very detailed, although sometimes erroneous, map of the Caspian Sea was compiled in the 17th century by the famous scientist and traveler, the German Adam Olearius. Peter I repeatedly traveled towards the Caspian Lake, and based on the data he provided, Russian hydrographers compiled very detailed maps of the Caspian Sea.

Since the 17th century, exploration of the Caspian Sea and its coastal environs has become systematic and versatile. Peter the Great in 1714 sent a research expedition under the leadership of Bekovich-Cherkassky. A few years later, research was continued by Verdun and Soimonov, and a little later by Tokmachev, Voinovich and other scientists.

At the beginning of the 19th century, an instrumental survey of the coast was carried out by I.F. Kolodkin; several decades later, a geographical survey was carried out by an expedition led by N.A. Ivashintsev. For half a century, starting from 1866, regular hydrological and hydrobiological expeditions were carried out under the leadership of N.M. Knipovich.

During the first years of Soviet power, the Caspian Sea was actively explored by geologists, mainly in search of oil product deposits, studying the water balance and fluctuations in water height in the lake.

History of the Caspian Lake

The Caspian Lake is located on the site of one of the giant reservoirs of antiquity. The origin of the Caspian Lake is inextricably linked with the ancient Sea of ​​Tetris, which more than 50-55 million years ago united the Pacific and Atlantic oceans, located on the territory of the present Caspian, Azov, Black and Mediterranean seas.

After long, complex tectonic movements, Tetris was first cut off from Pacific Ocean, and a little later the Atlantic.

About 5-6.5 million years ago, the giant reservoir broke into small basins, which included the Caspian and Black Sea.

After that, they repeatedly united and moved apart.

1.8-2 million years ago the Caspian Sea was finally cut off from the waters of the World Ocean and it was this time that is considered the beginning of its origin.

Throughout its history, the lake has changed its shoreline many times until it acquired its current appearance.

Physiographic characteristics of the Caspian Lake

The water surface of the lake is noticeably lower than the level of the World Ocean and amounts to -27.5...-28.5 m. The area of ​​the Caspian Sea varies depending on the level and water and is in the range of 380-390 km2, the total volume is 73.7-74.1 km3 .

The Caspian Sea is geographically divided into several parts with their own characteristics:

1. Northern Caspian— it accounts for 24% of the total area of ​​the reservoir. This part is shallow, and its average depth does not exceed 6 m, the maximum reaches 25 m, the volume of water is less than 1%.
2. Middle Caspian– 36% of the total area of ​​the lake falls on it. This part of the lake is a kind of basin with a maximum depth of almost 800 m and an average depth of 190 m. It contains a third of the total volume of water.
3. Southern Caspian– occupies 40% of the total area of ​​the lake and accounts for the deepest part of the reservoir. It contains 2/3 of the volume of all water - 66%. The average depth is 340 m, and the deepest depression is 1025 m.

The length of the coastline reaches almost 7 thousand km. The maximum length of the lake is slightly more than 1 thousand km, and the widest point is 435 km. The minimum width is considered to be a segment of 195 km. The average width is considered to be 317 km.

Map of the depth of the Caspian lake

The shores vary greatly in their landscape. North coast flat and low, around it there is a semi-desert in the lowlands, and on the hill there is a desert. The southern coastline is partly lowland and partly mountainous and consists of the Elbrus ridge. The Caucasus Mountains come close to the western part.

The eastern coastline is a calcareous plateau of desert and semi-desert type. The outlines of the coast vary greatly depending on the water level, which fluctuates periodically.

Climate

The water temperature of the Caspian Sea fluctuates significantly depending on latitude. This amplitude is most noticeable in winter, when the water under the ice in the northern part has a temperature of 0.-0.5 °C above zero, while in the south at this time it is 10-11 °C.

According to average data, the temperature in the western part of the lake is up to 2 °C higher than in the eastern part, and when moving away from the shore it increases by 2-4 °C compared to the coastal zone. In summer, the water in the lake warms up to 23-29 °C, and in shallow water in the northern part it can reach 34-40 °C. Below 100 m, the temperature stabilizes at 4-7 °C.

The Caspian Lake is located three climatic zones: continental (north of the reservoir), temperate (middle) and subtropical (Southern Caspian). in winter average temperature ranges from -8 to -11 °C in the north and to +8 to +11 °C in the south of the lake.

In summer, the northern part warms up to 24-25 °C with a positive mark, in the south the temperature rises to 26-27 °C. The highest temperature of +44 °C was recorded in the east of the reservoir.

The average annual precipitation is about 200 mm. Moreover, on the arid eastern coast at least 90-100 mm falls; in the southwest these figures can reach 1700 mm. The average annual wind speed is in the range of 3-8 m/s, mainly winds from the north prevail. In autumn and winter, their speed increases and can reach 35-39 m/s.

When the thermometer shows large subzero values ​​in the northern part of the lake, south coast trees and flowers bloom. In winter, the surface of the lake is unstable and stormy winds prevail. In winter, only the northern shallow waters freeze; during severe winter frosts, the Northern Caspian and the coastal waters of the Middle Caspian are covered with ice.

Flora and fauna

The flora of the Caspian Sea and its coastal environs consists of more than 720 plant species. The lake is mainly dominated by algae (diatoms, brown algae, etc.), and angiosperms - rupee and zoster. Most of the vegetation of the Caspian Lake originates from the Neogene period, but some entered the reservoir on the bottoms of ships or deliberately, with the help of humans.

Among the animal representatives of the Caspian Sea and its environs, there are more than 1,800 species, of which more than 400 are vertebrates, and more than 90 species are fish (sturgeon, carp, bream, mullet, beluga, etc.). Mammals are represented only by the Caspian seal, which is the smallest of the seal family and lives exclusively in the Caspian Lake.

The lake is home to the largest school of sturgeon in the world, and a lot of pike perch, carp and roach live in the sea waters. Up to 80% of the total world sturgeon catch and more than 90% of the world black caviar fishery come from the Caspian Lake.

The main route of bird migration between Europe and Asia passes over the Caspian Sea (in spring - in south direction, and in the fall - in the north). During seasonal migrations, over 11.5 million birds fly over the lake, about 5 million individuals remain for the winter. The lake itself is home to over 850 species of animals, of which almost 80 are vertebrates. More than 500 species of plants are present in the lake.

Islands

The Caspian Lake contains more than 50 large and medium-sized islands with a total area of ​​about 350 square meters. km.

State to which the island belongs	Island name
Azerbaijan	Jasper
	Oil Rocks
	pelicanium
	Zenbil
	Sengi Mugan
	Boyuk-Zira
	Baku archipelago
	Kichik Zira
	Kurinsky
	Chilov
	Ignat Dashi
	Inner Stone
	Khyarya Zira
	Kara Su
	Dash Zira
	Novoivanovsky
	Chikil
	Kurinskaya braid
	Gil
	Baburiy
Iran	Ashur-Ada
Kazakhstan	Seal Islands
	Average
	Südev
	Konevsky Oseredok
	Somyonok
	Babiy
	Somovy
Turkmenistan	Ogurchinsky
	Bolshoi Zyudostinsky
	Marine Ivan-Guard
	Clean Jars
	Maly Zyudostinsky
	little birdie
	Egg
	Maly Setnoy
	Jumpers
	Sandy
	Bazaar
	Konevsky
	Green
	Sea Privet
	Batkachny
	Nordic
	Maly Zhemchuzhny
	Big Setnoy
	Blinov
	Upper Oseredok
	Khokhlatsky
	Südev
	Lower
	Small
	Likhachev
	Seal
	Seventh
	Marine Chapura
	Chechen

Flowing rivers

More than 130 rivers flow into the Caspian Sea, 9 of which have delta-shaped mouths. 95% of water enters the Caspian Sea from rivers. Most of them flow into the lake in the northern and western parts of the reservoir; there are no flowing rivers in the east.

The largest and most significant rivers of the Caspian basin:

Approximately 88% of the total flow comes from rivers such as the Volga, Terek, Ural and Emba, which flow into the northern Caspian Sea. 7% of the flow falls on rivers such as the Kura, Sulak, Samur and other smaller ones flowing into the western part of the Caspian Sea. About 5% of the flow of the Sefidrud, Kheraz and Gorgan rivers enters the Iranian part of the reservoir.

Ecological state

The condition of the Caspian Lake and surrounding areas causes concern among environmentalists.

The main causes of environmental problems are related to man and his activities:

• production and transportation of oil and gas products;
• influx of pollutants from river runoff waters;
• poaching;
• waste from coastal cities;
• rapid jumps in water levels in the Caspian Sea due to irrigation of lands with waters of inflowing rivers and the use of hydroelectric power stations.

How is the Caspian Lake used?

The Caspian Lake has been actively used by humans for many centuries.

Main directions of economic activity:

Recreational resources of the Caspian Lake

The climate and nature of the Caspian coast with its clean sand beaches, healing mud and healing springs provide great potential and excellent conditions for sanatorium treatment and tourist recreation.

The development of the resort and tourism infrastructure, although noticeably inferior to the similar industry on the Black Sea coast, is actively expanding and the quality of service is improving. The most noticeable surge in development in recent years has been observed in the Republic of Dagestan, Iran, Turkmenistan and Azerbaijan.

Holidays on the Caspian coast in the Russian Federation and former countries The CIS is characterized by low cost and on average the quality in some places is inferior to that in the Black Sea, but in actively developing places the level is quite high.

Popular recreation areas with developed infrastructure:

• Baku;
• Amburan;
• Makhachkala;
• Bilgah;
• Derbent.
• Nabran;
• Lankaran;
• Nardaran.

The development of the Turkmen resort and tourism industry is hampered by internal policies that isolate the state from the majority of tourists. And in Iran, mass recreation is difficult due to strict Sharia laws.

There are 3 protected areas on the coast:

The Caspian Lake is located at the junction of Europe and Asia and is the largest lake in the world.

There are many interesting facts about the reservoir:

1. Its size is larger than Japan, but its area is smaller than Germany.
2. In terms of depth, the Caspian Sea is in third place, second only to Tanganyika and Baikal.
3. Every 2.5 centuries the waters are completely renewed.
4. Albino beluga sturgeon, whose caviar is the most expensive in the world, is caught on the Iranian coast. It is distinguished by a white tint and is packaged in unusual jars made of real gold.
5. The largest beluga weighed more than 1200 kg and was caught in the 20s. XX century on the Russian coast. In its dimensions it is comparable to a large shark.
6. Throughout the history of the lake, it has had more than 70 different names.
7. Scientists are still debating whether to consider the Caspian Lake a sea, arguing that its area exceeds the size of some seas, and the bottom is created according to the oceanic type. But at the same time, the reservoir is endorheic and is not connected to the ocean or other seas.
8. The smallest coastline of the five countries belongs to the Russian Federation.
9. More than 80% of the water enters the lake from the river. Volga.

The Caspian Lake is rich in flora and fauna, distinguished by warm waters and a long swimming season. It is best known for its depth and size, production of oil, gas and sturgeon, the reserves of which exceed those known throughout the world.

The lake is 95% supplied with runoff water from rivers. On its coast there are many resorts and sanatoriums, whose attractiveness can be appreciated, and at affordable prices.

Article format: Mila Friedan

Video about the Caspian Sea

Film about the Caspian Sea: