The Caspian Sea is cold or not. Caspian states: borders, map

18.10.2021

In a dry and hot climate, a large amount of seawater evaporates, water molecules pass into the air. So, every year, such a huge amount of water particles are carried away from the surface of the Caspian Sea that together they would fill a bowl with a volume of several hundred cubic kilometers. This amount of water could fill ten such reservoirs, which will be Kuibyshev.

But can water from the sea surface get into the bottom layers of the Caspian, to a depth of 900-980 meters?

This is possible provided that the density of the surface water layers is greater than the density of the bottom layers.

It is known that the density of seawater depends on salinity and temperature. The more salts the water contains, the denser and therefore heavier it is. High temperature water is less dense than cold water. Only at low temperatures (about 0-4 ° C) is the opposite ratio given, when the water, warming up, becomes denser.

High salinity of the surface layers of the sea is created during the hot season, when the water evaporates strongly, while the salt remains in the sea. At this time, the salinity of surface waters turns out to be no less, and even slightly more than the salinity of the deep and bottom layers.

The temperature of surface waters in the warm season is the same everywhere, about 25-28 °, that is, five times higher than at a depth of 150-200 meters. With the onset of the cold season, the temperature of the surface layers decreases and in a certain period turns out to be 5-6 ° above zero.

The same (5-6 °) temperature of the bottom and deep (deeper than 150-200 m) layers of the Caspian Sea is practically unchanged throughout the year.

Under these conditions, the sinking of denser surface cold and highly saline water into the bottom layers is possible.

Only in the southern regions of the Caspian the surface water temperature, as a rule, does not drop to 5-6 °, even in winter. And, although the subsidence of surface waters in the depths cannot occur directly in these areas, water is brought here by deep currents, which descended from the surface in the more northern parts of the sea.

A similar phenomenon is observed in the eastern part of the border zone between the Middle and South Caspian, where cooled surface waters descend along the southern slope of the border submarine sill and then follow in a deep current to the southern regions of the sea.

Such ubiquitous mixing of surface and deep waters is confirmed by the fact that oxygen was found at all depths of the Caspian.

Oxygen can only get to depths with the surface layers of water, where it comes directly from the atmosphere or as a result of photosynthesis.

If there was no continuous supply of oxygen to the bottom layers, it would quickly be absorbed there by animal organisms or spent on the oxidation of soil organic matter. Instead of oxygen, the bottom layers would be saturated with hydrogen sulfide, which is observed in the Black Sea. In it, the vertical circulation is so weak that sufficient oxygen does not reach the depth, where hydrogen sulfide is formed.

Although oxygen is found at all depths of the Caspian Sea, it is far from the same amount in different seasons of the year.

The water column is richest in oxygen in winter. The more severe the winter, that is, the lower the surface temperature, the more intense the aeration process, which reaches the deepest parts of the sea. Conversely, several warm winters in a row can cause the appearance of hydrogen sulfide in the bottom layers and even the complete disappearance of oxygen. But such phenomena are temporary and disappear in the very first more or less severe winter.

The upper water column is especially rich in dissolved oxygen down to a depth of 100-150 meters. Here, the oxygen content ranges from 5 to 10 cubic meters. cm in liter. At depths of 150-450 m oxygen is much less - from 5 to 2 cubic meters. cm in liter.

Deeper than 450 m, there is very little oxygen and life is represented very poorly - several species of worms and molluscs, the smallest crustaceans.

The mixing of water masses is also caused by surges and waves.

Waves, currents, winter vertical circulation, surges, surges operate constantly and are important factors in the mixing of waters. It is not surprising, therefore, that wherever we take a water sample in the Caspian Sea, its chemical composition will be constant everywhere. If there was no mixing of waters, all living organisms of great depths became extinct. Life would be possible only in the zone of photosynthesis.

Where the waters mix well and this process proceeds quickly, for example, in shallow areas of the seas and oceans, life is richer.

The constancy of the salt composition of the Caspian Sea water is a common property of the waters of the World Ocean. But this does not mean that the chemical composition of the Caspian is the same as in the ocean or in any sea connected to the ocean. Consider a table showing the salt content in the waters of the ocean, the Caspian and the Volga.

	Carbonates (CaCO 3)	Sulfates CaSO 4, MgSO 4	Chlorides NaCl, KCl, MgCl 2	Average salinity of waters ‰
Ocean	0,21	10,34	89,45
Caspian Sea	1,24	30,54	67,90	12,9
Volga river	57,2	33,4

The table shows that ocean water has very little in common with river water in terms of salt composition. In terms of salt composition, the Caspian Sea occupies an intermediate position between the river and the ocean, which is explained by the great influence of the river runoff on the chemical composition of the Caspian water. The ratio of salts dissolved in the water of the Aral Sea is closer to the salt composition of river water. This is understandable, since the ratio of the volume of river flow to the volume of the Aral Sea is much greater than for the Caspian. The large amount of sulfate salts in the Caspian Sea gives its water a bitter-salty taste, which distinguishes it from the waters of the oceans and the seas connected to them.

The salinity of the Caspian Sea is continuously increasing towards the south. In the pre-estuary space of the Volga, a kilogram of water contains hundredths of a gram of salt. In the eastern regions of the South and Middle Caspian, salinity reaches 13-14 ‰

The concentration of salts in the Caspian water is low. So, in this water you can dissolve salts almost twenty times more than they are in it.

B.A. Shlyamin. Caspian Sea. 1954

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, Kazakhstan, Turkmenistan, Iran, Azerbaijan

Geographical position

Caspian Sea - view from space.

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

The Caspian Sea is conventionally divided by physical and geographical conditions into 3 parts - the North Caspian, the Middle Caspian and the South Caspian. The conditional border between the North and Middle Caspian runs along the line about. Chechnya - Cape Tyub-Karagan, between the Middle and South Caspian - along the line of about. Residential - Cape Gan-Gulu. The area of the North, Middle and South Caspian Sea is 25, 36, 39 percent, respectively.

Caspian Sea coast

Coast of the Caspian Sea in Turkmenistan

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

Peninsulas of the Caspian Sea

Ashur-Ada
Garasu
Zyanbil
Hara-Zira
Sengi-Mugan
Chygyl

Bays of the Caspian Sea

Russia (Dagestan, Kalmykia and the Astrakhan region) - in the west and north-west, the length of the coastline is about 1930 kilometers
Kazakhstan - in the north, north-east and east, the length of the coastline is about 2320 kilometers
Turkmenistan - in the southeast, the length of the coastline is about 650 kilometers
Iran - in the south, the length of the coastline is about 1000 kilometers
Azerbaijan - in the south-west, the length of the coastline is about 800 kilometers

Cities on the coast of the Caspian Sea

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

Physiography

Area, depth, volume of water

The area and volume of water in the Caspian Sea varies significantly depending on the fluctuations in the water level. 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 above its surface. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated according to the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, charovy and others, from flowering plants - zostera and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into the Caspian Sea by humans deliberately or on the bottoms of ships.

History of the Caspian Sea

Origin of the Caspian Sea

Anthropological and cultural history of the Caspian Sea

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

Exploration of the Caspian Sea

The exploration of the Caspian Sea was started by Peter the Great, when, on his order, in 1714-1715, an expedition was organized under the leadership of A. Bekovich-Cherkassky. In the 1720s, hydrographic research was continued by the expedition of Karl von Verden and F.I.Soimonov, and later by I.V. Tokmachev, M.I.Voinovich and other researchers. At the beginning of the 19th century, instrumental survey of the coast was carried out by I.F.Kolodkin, in the middle of the 19th century. - instrumental geographic survey under the direction of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary research on the hydrology and hydrobiology of the Caspian has been conducted under the leadership of N.M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power in the Caspian Sea, geological research by I. M. Gubkin and other Soviet geologists was actively carried out, mainly aimed at finding oil, as well as research to study the water balance and fluctuations in the level of the Caspian Sea.

Economy of the Caspian Sea

Mining of oil and gas

Many oil and gas fields are being developed in the Caspian Sea. The proven oil resources in the Caspian Sea are about 10 billion tons, the total oil and gas condensate resources are estimated at 18-20 billion tons.

Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf near Baku. In the second half of the 19th century, oil production began in industrial volumes on the Apsheron Peninsula, then in other territories.

Shipping

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

Fishing and seafood production

Fishing (sturgeon, bream, carp, pike perch, sprat), caviar and seal fishing. More than 90 percent of the world's sturgeon catch is carried out in the Caspian Sea. In addition to industrial production, illegal production of sturgeon and their caviar is flourishing in the Caspian Sea.

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and curative mud in the coastal area creates good conditions for recreation and treatment. At the same time, in terms of the development of resorts and tourism industry, the Caspian coast is noticeably inferior to the Black Sea coast of the Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coast of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. A resort area in the Baku region is actively developing in Azerbaijan. At the moment, a world-class resort has been created in Amburan, another modern tourist complex is being built in the area of the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also developing in Nabran, in the north of Azerbaijan. However, high prices, generally low level of service and lack of advertising lead to the fact that there are almost no foreign tourists in the Caspian resorts. The development of the tourism industry in Turkmenistan is hindered by a long-term policy of isolation, in Iran - by Sharia law, which makes it impossible for foreign tourists to spend mass vacations on the Caspian coast of Iran.

Ecological problems

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

International status of the Caspian Sea

Legal status of the Caspian Sea

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

With regard to the Caspian, the key is the physical and geographical circumstance that it is a closed inland water body that does not have a natural connection with the World Ocean. Accordingly, the norms and concepts of international maritime law should not be automatically applied to the Caspian Sea, in particular, the provisions of the 1982 UN Convention on the Law of the Sea. economic zone "," continental shelf ", etc.

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

Negotiations on the legal status of the Caspian are ongoing.

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

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

, Kazakhstan, Turkmenistan, Iran, Azerbaijan

Geographical position

Caspian Sea - view from space.

Caspian Sea coast

Coast of the Caspian Sea in Turkmenistan

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

Peninsulas of the Caspian Sea

Ashur-Ada
Garasu
Zyanbil
Hara-Zira
Sengi-Mugan
Chygyl

Bays of the Caspian Sea

Russia (Dagestan, Kalmykia and the Astrakhan region) - in the west and north-west, the length of the coastline is about 1930 kilometers
Kazakhstan - in the north, north-east and east, the length of the coastline is about 2320 kilometers
Turkmenistan - in the southeast, the length of the coastline is about 650 kilometers
Iran - in the south, the length of the coastline is about 1000 kilometers
Azerbaijan - in the south-west, the length of the coastline is about 800 kilometers

Cities on the coast of the Caspian Sea

Physiography

Area, depth, volume of water

Water level fluctuations

Vegetable world

History of the Caspian Sea

Origin of the Caspian Sea

Anthropological and cultural history of the Caspian Sea

Exploration of the Caspian Sea

Economy of the Caspian Sea

Mining of oil and gas

Shipping

Fishing and seafood production

Recreational resources

Ecological problems

International status of the Caspian Sea

Legal status of the Caspian Sea

Negotiations on the legal status of the Caspian are ongoing.

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

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

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

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

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

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

Why is the Caspian called a lake?

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

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

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

Why is the Caspian called the sea?

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

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

origin of name

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

Iranians and Azerbaijanis still call it the Khazar Sea. It began to be called Caspian by the name of the ancient tribe of nomadic horse breeders who lived in the steppes adjacent to its coast - the numerous tribe of the Caspians. They gave the name to the largest lake on our planet - the Caspian Sea.

The coastline of the Caspian Sea is estimated at about 6500 - 6700 kilometers, with islands up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low and smooth. In the northern part, the coastline is cut by water streams and islands of the Volga and Ural deltas, the shores are low and swampy, and the water surface is covered with thickets in many places. The eastern coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding shores are on the western coast in the area of the Absheron Peninsula and on the eastern coast in the area of the Kazakh Bay and Kara-Bogaz-Gol.

Peninsulas of the Caspian Sea

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

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

The largest islands:

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

Large bays of the Caspian Sea:

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

Rivers flowing into the Caspian Sea

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

Basin of the Caspian Sea

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

Coastal states

The Caspian Sea washes the shores of five coastal states:
* Russia (Dagestan, Kalmykia and the Astrakhan region) - in the west and northwest, the length of the coastline is 695 kilometers
* Kazakhstan - in the north, north-east and east, the length of the coastline is 2320 kilometers
* Turkmenistan - in the southeast, the length of the coastline is 1200 kilometers
* Iran - in the south, the length of the coastline is 724 kilometers
* Azerbaijan - in the southwest, the length of the coastline is 955 kilometers

Cities on the coast of the Caspian Sea

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

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

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

Area, depth, volume of water

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

Water level fluctuations

The water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past 3 thousand years, the amplitude of changes in the water level of the Caspian Sea was 15 meters. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuation have been conducted since 1837, during this time the highest water level was recorded in 1882 (-25.2 m), the lowest - in 1977 (-29.0 m) , since 1978 the water level has been rising and in 1995 reached the level of -26.7 m, since 1996 there has been a tendency for the level of the Caspian Sea to decrease again. Scientists associate the reasons for the change in the water level of the Caspian Sea with climatic, geological and anthropogenic factors.

Water temperature

The water temperature is subject to significant latitudinal changes, most pronounced in winter, when the temperature varies from 0-0.5 ° C at the ice edge in the north of the sea to 10-11 ° C in the south, that is, the difference in water temperature is about 10 ° C. For shallow areas with depths less than 25 m, the annual amplitude can reach 25-26 ° C. On average, the water temperature near the western coast is 1–2 ° C higher than that of the eastern one, and in the open sea the water temperature is 2–4 ° C higher than that near the coasts. By the nature of the horizontal structure of the temperature field in the annual cycle of variability, three time segment in the upper 2-meter layer. From October to March, the water temperature increases in the southern and eastern, which is especially well traced in the Middle Caspian. Two stable quasi-latitude zones can be distinguished, where temperature gradients are increased. This is, firstly, the border between the North and Middle Caspian, and, secondly, between the Middle and South. At the ice edge, in the northern frontal zone, the temperature in February-March increases from 0 to 5 ° C, in the southern frontal zone, in the area of the Apsheron sill, from 7 to 10 ° C. During this period, the least cooled waters are in the center of the South Caspian, which form a quasi-stationary core.

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

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

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

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

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

Water composition

The salt composition of the waters of the enclosed Caspian Sea differs from that of the ocean. There are significant differences in the ratios of the concentrations of salt-forming ions, especially for the waters of areas under the direct influence of continental runoff. The process of metamorphization of sea waters under the influence of continental runoff leads to a decrease in the relative content of chlorides in the total amount of salts of sea waters, an increase in the relative amount of carbonates, sulfates, calcium, which are the main components in the chemical composition of river waters. The most conservative ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ions. In the Caspian, the content of calcium and magnesium cations is almost two times higher than in the Sea of Azov, and the content of sulfate anions is three times higher. The salinity of the water changes especially sharply in the northern part of the sea: from 0.1 units. psu in the mouth areas of the Volga and the Urals up to 10-11 units. psu on the border with the Middle Caspian.

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

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

Bottom relief

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

Climate

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

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

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

Currents

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

Animal world

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

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, charovy and others, and of flowering plants - zostera and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into the Caspian Sea by humans deliberately or on the bottoms of ships.

Origin of the Caspian Sea

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

Anthropological and cultural history of the Caspian Sea

Exploration of the Caspian Sea

The exploration of the Caspian Sea was started by Peter the Great, when, on his order, in 1714-1715, an expedition was organized under the leadership of A. Bekovich-Cherkassky. In the 1820s, hydrographic research was continued by I. F. Soyomov, and later by I. V. Tokmachev, M. I. Voinovich and other researchers. At the beginning of the 19th century, instrumental survey of the banks was carried out by I.F.Kolodkin, in the middle of the 19th century. - instrumental geographic survey under the direction of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary research on the hydrology and hydrobiology of the Caspian has been conducted under the leadership of N.M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power in the Caspian Sea, geological research by I. M. Gubkin and other Soviet geologists was actively carried out, mainly aimed at finding oil, as well as research to study the water balance and fluctuations in the level of the Caspian Sea.

Mining of oil and gas

Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf. In the second half of the 19th century, oil production began in industrial volumes on the Absheron Peninsula, then in other territories.

In addition to oil and gas production, salt, limestone, stone, sand and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.

Shipping

Fishing and seafood production

Recreational resources

Ecological problems

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

Frontier dispute over the status of the Caspian Sea

After the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of the resources of the Caspian shelf - oil and gas, as well as biological resources. For a long time, negotiations were going on between the Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran - on dividing the Caspian by one fifth between all the Caspian states. In 2003, Russia, Azerbaijan and Kazakhstan signed an agreement on the partial division of the Caspian Sea along the median line.

Coordinates: 42.622596 50.041848