Caspian Sea. Where is located, photo, characteristics, area, resorts for recreation

In a dry and hot climate, a large amount of sea water evaporates, water molecules pass into the air. So, every year such a huge amount of water particles is carried away from the surface of the Caspian Sea that all 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 layers of water is more density bottom layers.

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

The high salinity of the surface layers of the sea is created in the hot season, when water evaporates strongly, while salt remains in the sea. At this time, the salinity of surface waters is not less, and even somewhat greater than the salinity of the deep and bottom layers.

Surface water temperature in warm time year 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 it turns out to be 5-6° above zero.

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

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

It is only in the southern regions of the Caspian that the surface water temperature, as a rule, does not drop to 5-6°C even in winter. And, although the sinking of surface waters into the depths cannot occur directly in these areas, water is brought here by deep currents, which has 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 underwater threshold and then follow the deep current to the southern regions of the sea.

Such widespread mixing of surface and deep waters is confirmed by the fact that oxygen has been found at all depths of the Caspian Sea.

Oxygen can get to the depths only 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 by animal organisms there or spent on the oxidation of the organic matter of the soil. 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 oxygen in sufficient quantities 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 being in 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 temperature on the surface, 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 first more or less severe winter.

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

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

Mixing of water masses is also caused by surge phenomena and waves.

Waves, currents, winter vertical circulation, surges, surges act constantly and are important factors in the mixing of waters. It is not surprising, therefore, that no matter where in the Caspian Sea we take a water sample, everywhere chemical composition her will be constant. If there was no mixing of waters, all living organisms of great depths would die out. 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 water of the Caspian Sea 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)	Sulphates 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 a river and an ocean, which is explained by the great influence of river runoff on the chemical composition of Caspian water. The ratio of salts dissolved in water Aral Sea, closer to the salt composition of river water. This is understandable, since the ratio of the volume of river runoff to the volume of the waters of the Aral Sea is much larger than for the Caspian. A large number of sulfate salts in the Caspian Sea gives its water a bitter-salty taste that 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 salts. In the eastern regions of the South and Middle Caspian, salinity reaches 13-14‰

Salt concentration in Caspian water small. So, almost twenty times more salts can be dissolved in this water than there are in it.

B.A. Shlyamin. Caspian Sea. 1954

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The Caspian Sea is rightfully the largest lake on the entire planet and this sea-lake is located at the junction of two significant parts of the world: Asia and Europe.

Until now, there are disagreements in the name of the Caspian Sea: is it a sea or a lake. And it is called the sea due to the large size of the reservoir.

Origin of the sea

The Caspian Sea has an oceanic origin. It was formed approximately 10 million years ago as a result of the division of the Sarmatian Sea.

According to one of the legends, the Caspian reservoir received its modern name in honor of the Caspian tribes living on the southwestern shores. For all the time, the Caspian Sea has changed its name about 70 times.

currents

The water area of ​​the Caspian Sea can be divided into the following three parts:

• southern (39% of the area)
• medium (36% of the total area)
• northern part (25% of the area).

The currents of the reservoir are formed as a result of the following influences: the general influence of the wind regime, density differences in certain areas and the flow of inflowing rivers.

Off the western coast of the middle part of the Caspian, southern and southeastern currents predominate. For the middle and southern parts of the Caspian Sea, depending on the direction of the winds, currents of the northern, northwestern, southern and southeastern directions are characteristic. Eastern currents prevail in the eastern part of the Caspian.

The following currents also play an important role in the Caspian water cycle:

• seiche;
• gradient;
• inertial.

Which rivers flow into the Caspian Sea

The bulk of the river waters enter the Caspian through the Volga River. In addition to the Volga, the following rivers flow into this reservoir:

• Samur, flowing on the border of Azerbaijan and Russia;
• Astarachay, flowing on the border of Iran and Azerbaijan;
• Kura located in Azerbaijan;
• Kheraz, Sefudrud, Tejen, Polerud, Chalus, Babol and Gorgan flowing in Iran;
• Sulak, Kuma, located on the territory of the Russian Federation;
• Emba and Ural flowing in Kazakhstan;
• Atrek located in Turkmenistan.

Sulak river photo

Where does the Caspian Sea flow into?

The Caspian reservoir has no connection with the ocean, since it is an endorheic reservoir. The Caspian Sea has dozens of bays. The largest of them can be distinguished: Komsomolets, Gyzlar, Kara-Bogaz-Gol, Mangyshlak, Kazakh, Krasnovodsk and others. Also in the waters of the Caspian Sea there are about 50 islands of different sizes, with a total area of ​​more than 350 km2. Some of the islands are grouped into archipelagos.

Relief

The following forms can be distinguished in the relief of the bottom of the Caspian Sea: in the south of the reservoir there are deep-water depressions; continental slope, starting just below the shelf line and descending to the southern part of the Caspian Sea up to 750 m, and in the middle part of the Caspian Sea - up to 600 m. shelf, the length of which from the depth to the coastline is 100 m and is covered with shell sands, and in deep water - with silty sediments.

Derbent photo

The coastline of the northern region of the sea is low-lying, quite indented, in some areas it is flat. The western shore of the reservoir is indented and mountainous. In the east, the coasts are distinguished by elevations. The southern coastline is mostly mountainous. The Caspian Sea is located in a zone of high seismicity. Also, mud volcanoes often erupt here, most of which are located in the southern part of the reservoir.

Cities

The following states have access to the waters of the Caspian Sea:

• Russia. A large city is Makhachkala, the capital of Dagestan. Also in Dagestan are the cities of Kaspiysk and Izberbash. In addition to the above cities in the Russian Federation on the Caspian Sea, Derbent, the southernmost city of Russia located on the western coast of the Caspian Sea, Olya in the Astrakhan region, should be noted.
• Azerbaijan: The port city of Baku, the capital of Azerbaijan, is located in the southern part of the Absheron Peninsula. Another large city is Sugmait, located in the northern part of the peninsula. The resorts of Nabran and Lankaran should also be noted. The latter is located near the southern border of Azerbaijan.
• Turkmenistan with the port city of Turkmenbashi.
• Iran: Bandar-Torkemen, Anzeli, Nowshahr.

Makhachkala photo

Flora and fauna

The entire fauna of the Caspian Sea can be conditionally divided into the following groups:

• The first group consists of descendants of ancient organisms: representatives of herring (shad, Volga, Kessler and Brazhnikovskaya herring); representatives of the Caspian gobies (golovach, pugolovka, Berg, Baer, ​​Knipovich and Bubyr); sprats; a large number of crustaceans; some types of shellfish.
• The second group includes representatives of the fauna that entered the sea from the north in the post-glacial era of desalination of the reservoir: seal; fish species: perch, cyprinids, nelma, white salmon and trout; some representatives of crustaceans: sea cockroaches, mysid crustaceans and others.
• The third group includes species that came to the Caspian Sea from the Mediterranean Sea: the following types of fish: golden mullet, flounder and needle fish; representatives of mollusks; representatives of crustaceans: shrimps, amphipods, crabs.
• The fourth group includes representatives of freshwater fish that got into the Caspian Sea from fresh rivers: stellate sturgeon, beluga, sturgeon, Caspian fish, red-lipped asp, barbel, pike perch, catfish.

sturgeon photo

The water area of ​​the Caspian Sea is the main and main habitat for sturgeon representatives on the entire planet. Almost 80% of all sturgeons in the world live in the sea. Sharks and various predatory fish that carry any danger to humans do not live in this reservoir.

The flora of the Caspian Sea is represented by more than 700 species of lower plants (phytoplankton), as well as 5 species of higher plants (spiral and sea ruppia, comb pondweed, zoster, sea mollusk). Here you can meet various waterfowl. Some of them come here for wintering from the north (waders, loons, gulls, geese, swans, ducks, geese), some come from the south for nesting (eagles).

Characteristic

Let's get acquainted with the main characteristics of the Caspian Sea:

• The length from north to south was approximately 1200 km;
• The width of the basin from west to east is approximately 200-435 km;
• The total area of ​​the Caspian is approximately 390,000 km2;
• The volume of sea waters is 78000 km3.
• The maximum sea depth is about 1025m.
• The salinity of the water is on average up to 13.2%.

Sea level is below the level of the oceans. The north of the Caspian is characterized by a continental climate. The middle Caspian is characterized by a temperate climate. The southern part of the sea is characterized by a subtropical climate. In winter, the average temperature in the north varies from 8 to 10 degrees of frost, and in the south from 8 to 10 degrees of heat. In summer, the average temperature in the north is 24-25 degrees above zero, and in the south 26-27 degrees of heat.

Caspian Sea. birds photo

• To this day, scientists are arguing: what status to give the Caspian sea or lake? After all, this reservoir is closed and drainless. At the same time, this reservoir prevails in size over some other seas.
• The bottom at the deepest point is separated from the water surface of the Caspian Sea by a distance of more than a kilometer. In the Caspian, the water level is unstable and tends to decrease.
• This reservoir had about 70 names that were given to it by different tribes and peoples living on the banks.
• There is a scientific theory that states that the Caspian and Black Seas were united into one sea in ancient times.
• The Volga River provides the Caspian with most of the river water.
• Since the Caspian is the main habitat for sturgeon fish on the planet, most of the black caviar in the world is produced here.
• The waters of the Caspian reservoir are constantly renewed every 250 years. The name of the reservoir, according to legend, comes from the name of the tribe that lived on its shores.
• The area of ​​the Caspian Sea exceeds the area of ​​Japan and slightly less than the area of ​​Germany.
• If this body of water is considered a lake: it will take the third place in terms of depth in the world, after Baikal and Tanganyika. The Caspian is also the largest lake on the planet.
• The Caspian Sea is very rich in natural resources. Oil, gas, limestone, salt, clay, stones and sand are mined here.
• The Caspian Sea has recently faced the following environmental problems: Sea pollution. Oil is the main pollutant of the sea, suppressing the development of phytoplankton and phytobenthos. In addition to oil, phenols and heavy metals enter the Caspian. All this leads to a decrease in oxygen production, resulting in the death of a large number of fish and other organisms. Also, pollution leads to disease of living organisms in the sea. Poaching is one of the main reasons for the sharp decline in sturgeon catches. Changes in natural biogeochemical cycles. Construction on the Volga deprives fish representatives of their natural habitats.
• The Caspian Sea is a very important object in the field of shipping and economy. This body of water is absolutely closed and isolated from the oceans. This is the distinctive uniqueness of the Caspian.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of regularities. The central part of the Northern Caspian is characterized by a fairly uniform distribution of oxygen. An increased oxygen content is found in the areas of the pre-estuary seashore of the Volga River, a lower one - in the southwestern part of the Northern Caspian. In the Middle and South Caspian, the highest oxygen concentrations are confined to coastal shallow areas and pre-estuary seashores of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.). In the deep-water regions of the Caspian Sea, the main pattern is preserved in all seasons - a decrease in oxygen concentration with depth. Due to the autumn-winter cooling, the density of the waters of the North Caspian increases to a value at which it becomes possible for the flow of North Caspian waters with a high oxygen content along the continental slope to significant depths of the Caspian Sea. The seasonal distribution of oxygen is mainly related to the annual course of water temperature and the seasonal ratio of production-destruction processes occurring in the sea. In spring, the production of oxygen in the process of photosynthesis quite significantly covers the decrease in oxygen due to a decrease in its solubility with an increase in water temperature in spring. In the areas of the estuarine coasts of the rivers feeding the Caspian Sea, in 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 of water masses and activation of photosynthesis processes, the leading factors in the formation of the oxygen regime in surface waters are photosynthetic processes, in near-bottom waters - biochemical oxygen consumption by bottom sediments. Due to the high temperature of the waters, the stratification of the water column, the large influx of organic matter and its intense oxidation, oxygen is quickly consumed with its minimal entry into the lower layers of the sea, as a result of which an oxygen deficiency zone is formed in the Northern Caspian. Intensive photosynthesis in the open waters of the deep-water regions of the Middle and South Caspian covers the upper 25-meter layer, where oxygen saturation is more than 120%. In autumn, in the well-aerated shallow water areas of the Northern, Middle and Southern Caspian, 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 rising. The spatial distribution of nutrients in the Caspian Sea reveals the following patterns:

- increased concentrations of biogenic substances are characteristic of the pre-estuary coastal areas of the rivers that feed the sea and shallow areas of the sea 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 cyclonic nature of the circulation contributes to the upwelling of deep waters with a high content of nutrients into the overlying layers of the sea;
– in the deep water areas of the Middle and South Caspian, the vertical distribution of nutrients depends on the intensity of the process of convective mixing, and their content increases with depth.

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

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

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

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

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

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

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

About 55,000 tons of oil products enter the Northern Caspian every year from Russia, including 35,000 tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.
The thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange and threatens the death of hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg/l, for phytoplankton - 0.1 mg/l.

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

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

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

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

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

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

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

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

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

Geography of the Caspian Sea

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

Lake or sea?

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

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

Physical quantities

Area, volume, depth

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

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

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

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

coast

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

sea ​​water temperature

(The temperature of the Caspian Sea at different times of the year)

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

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

Nature of the Caspian Sea

Islands, peninsulas, bays, rivers

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

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

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

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

Flora and fauna

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

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

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

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

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

Cities on the Caspian Sea

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

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

Interesting Facts

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

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

, 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 approximately 1200 kilometers (36°34 "-47°13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46°-56° v. d.).

The Caspian Sea is conditionally divided according to 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 of about. Chechnya - Cape Tyub-Karagansky, between the Middle and South Caspian - along the line of about. Residential - Cape Gan-Gulu. The area of ​​the Northern, Middle and Southern Caspian is 25, 36, 39 percent respectively.

Coast of the Caspian Sea

Coast of the Caspian Sea in Turkmenistan

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

Peninsulas of the Caspian Sea

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

Bays of the Caspian Sea

• Russia (Dagestan, Kalmykia and Astrakhan region) - in the west and north-west, the length of the coastline is about 1930 kilometers
• Kazakhstan - in the north, northeast 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 southwest, 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 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. At the same time, the northern part of the Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, char and others, of flowering - zoster and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were brought into the Caspian Sea by man either consciously 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 near the southern coast of the Caspian Sea indicate that a person lived in these parts about 75 thousand years ago. The first mention of the Caspian Sea and the tribes living on its coast are found in Herodotus. Approximately in the V-II centuries. BC e. Saka tribes lived on the coast of the Caspian Sea. Later, during the period of the settlement of the Turks, in the period of the 4th-5th centuries. n. e. Talysh tribes (Talysh) lived here. According to ancient Armenian and Iranian manuscripts, the Russians sailed the Caspian Sea from the 9th-10th centuries.

Exploration of the Caspian Sea

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

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 resources of oil and gas condensate are estimated at 18-20 billion tons.

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

Shipping

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

Fishing and seafood

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

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and therapeutic mud in the coastal zone creates good conditions for recreation and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast noticeably loses 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. The 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 near the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also being developed in Nabran, in the north of Azerbaijan. However, high prices, a generally low level of service and the 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 hampered by a long policy of isolation, in Iran - by Sharia law, due to which the mass vacation of foreign tourists on the Caspian coast of Iran is impossible.

Ecological problems

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

International status of the Caspian Sea

Legal status of the Caspian Sea

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

With regard to the Caspian Sea, 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, in particular, the provisions of the UN Convention on the Law of the Sea of ​​1982, should not automatically apply to the Caspian Sea. Based on this, 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 navigation in its waters of ships flying the flag of non-Caspian states.

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

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

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