Caspian states: borders, map. Which countries are washed by the Caspian Sea? Why is the Caspian Sea considered a lake?

21.10.2019

Many geographical names can mislead people who are not fond of geography. Could it be that the object marked on all maps as the sea is in fact a lake? Let's figure it out.

The history of the appearance of the Caspian Sea?

14,000,000 years ago, the Sarmatian Sea existed on the planet. It included modern, Black, Caspian and Azov seas. About 6,000,000 years ago, due to the rise of the Caucasus Mountains and the lowering of the water level in the Mediterranean Sea, it split, forming four different seas.

The Caspian is inhabited by many representatives of the fauna of Azov, which once again confirms that once these reservoirs were one. This is one of the reasons why the Caspian Sea is considered a lake.

The name of the sea comes from the ancient tribes of the Caspians. They inhabited its shores in the first millennia BC and were engaged in horse breeding. But over the long hundreds of years of its existence, this sea has had many names. It was called Derbent, Sarai, Girkan, Sigay, Kukkuz. Even in our time, for the inhabitants of Iran and Azerbaijan, this lake is called Khazar.

Geographic location

Two parts of the world - Europe and Asia, are washed by the waters of the Caspian Sea. The coastline covers the following countries:

Turkmenistan
Russia
Azerbaijan
Kazakhstan

The length from north to south is about one thousand two hundred kilometers, the width from west to east is about three hundred kilometers. The average depth is about two hundred meters, the greatest depth is about a thousand kilometers. The total area of the reservoir is more than 370,000 square kilometers and is divided into three climatic and geographical zones:

Northern
Average
South Caspian

The water area has six large peninsulas and about fifty islands. Their total area is four hundred square kilometers. The largest islands are Dzhambaisky, Ogurchinsky, Chechen, Tyuleniy, Konevsky, Zyudev and Absheron Islands. About one hundred and thirty rivers flow into the Caspian, including the Volga, Ural, Atrek, Sefirud, Terek, Kura and many others.

Sea or lake?

The official name used in documentation and cartography is the Caspian Sea. But is this true?

In order to have the right to be called a sea, any body of water must be connected to the oceans. In the case of the Caspian, this is not the reality. From the nearest sea, the Black Sea, the Caspian Sea is separated by almost 500 km of land. This is a completely enclosed reservoir. The main differences of the seas:

The seas can be fed by water arteries - rivers.
The outer seas are directly connected with the ocean, that is, they have access to it.
The inland seas are connected to other seas or oceans by straits.

The Caspian received the right to be called a sea primarily because of its impressive size, which is more characteristic of seas rather than lakes. In terms of area, it surpasses even Azov. Also, the fact that not a single lake washes the shores of five states at once played a significant role.

It should be noted that the structure of the bottom of the Caspian Sea belongs to the oceanic type. This happened due to the fact that it was once part of the ancient oceans.

Compared to other seas, the percentage of salt saturation in it is very weak and does not exceed 0.05%. The Caspian is fed only by rivers flowing into it, like all lakes on the globe.

Like many seas, the Caspian is famous for its powerful storms. The height of the waves can reach eleven meters. Storms can occur at any time of the year, but they are most dangerous in autumn and winter.

In fact, the Caspian Sea is the largest lake in the world. Its waters are not subject to international maritime laws. The territory of the waters is divided between countries on the basis of laws adopted for lakes, and not for seas.

The Caspian Sea has rich mineral resources such as oil and gas. Its waters are inhabited by more than one hundred and twenty species of fish. Among them are the most valuable sturgeons, such as stellate sturgeon, sturgeon, sterlet, beluga, and spike. 90% of the world's sturgeon catch goes to the Caspian Sea.

Interesting features:

Scientists around the world have not come to an unambiguous opinion why the Caspian Sea is considered a lake. Some experts even suggest considering it a "lake-sea" or "inland" sea, like the Dead Sea in Israel;
The deepest point of the Caspian is more than one kilometer;
Historically, it is known that the general water level in the reservoir has changed more than once. The exact reasons for this are still not understood;
This is the only body of water separating Asia and Europe;
The largest waterway that feeds the lake is the Volga River. It is she who carries the bulk of the water;
Thousands of years ago the Caspian Sea was part of the Black Sea;
In terms of the number of fish species, the Caspian Sea loses to some rivers;
The Caspian Sea is the main supplier of the most expensive delicacy - black caviar;
The water in the lake is completely renewed every two hundred and fifty years;
The territory of Japan is smaller than the area of the Caspian Sea.

Ecological situation

Intervention in the ecology of the Caspian Sea regularly occurs due to the extraction of oil and natural resources. There are also interventions in the fauna of the reservoir, cases of poaching and illegal catching of valuable species of fish are frequent.

The water level in the Caspian Sea is falling every year. This is due to global warming, due to the influence of which the water temperature on the surface of the reservoir increased by one degree and the sea began to actively evaporate.

It is estimated that the water level has fallen by seven centimeters since 1996. By 2015, the fall was about one and a half meters, and the water continues to fall.

If this continues, in a century the smallest part of the lake may simply disappear. This will be the part that washes the borders of Russia and Kazakhstan. In the case of increased global warming, the process can accelerate and this will happen much earlier.

It is known that long before the onset of global warming, the water level in the Caspian was undergoing changes. The water stayed and then fell. Scientists still cannot say exactly why this happened.

The Caspian Sea is inland and is 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.

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 its vastness, only 62.6% of its area is in 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 other features of the waters of the Caspian Sea), as well as the Kura River , Zhaiyk (Ural), Terek, Sulak, Samur.

In physical and geographical terms and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional boundary between the northern and middle parts runs along the line of Chechen Island–Cape Tyub-Karagan, between the middle and southern parts - along the line of Zhiloy Island–Cape Kuuli.

The shelf of the Caspian Sea, on average, is limited to depths of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at about 500–600 m, in the southern part, where it is very steep, at 700–750 m.

The northern part of the sea is shallow, its average depth is 5–6 m, the maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom relief is complicated by the presence of banks, islands, furrows.

The middle part of the sea is a separate basin, the region of maximum depths of which - the Derbent depression - is shifted to the western coast. The average depth of this part of the sea is 190 m, the greatest is 788 m.

The southern part of the sea is separated from the middle part by the Apsheron threshold, which is a continuation 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.

The shores of 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 in other areas 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 Bay stands out here with the Kenderli Bay and several capes. The largest bay of this coast is Kara-Bogaz-Gol.

South of the Absheron Peninsula are the islands of the Baku archipelago. The origin of these islands, as well as some banks off the eastern coast of the southern part of the sea, is associated with the activity of underwater mud volcanoes lying at the bottom of the sea. On 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 level 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 circulation systems interact, however, easterly winds prevail throughout the year (the influence of the Asian high). 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 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 very a large number of annual precipitation is 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 topography, isolation) have a certain influence on the formation 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 20 and 30 m in the middle part of the sea and 30 and 40 m in the south. 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-water depressions of the Middle and South Caspian, salinity fluctuations in top 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, coasts and landfast ice form off the coast, and drift ice spreads to the Absheron Peninsula in abnormally cold winters off the western coast. The disappearance of the ice cover is observed in the second half of February–March.

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 and 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 the significant warming up of water masses and the 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 inflow organic matter and its intense oxidation, oxygen is quickly consumed with its minimal entry into the lower layers of the sea, resulting in the formation of an oxygen deficiency zone 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 characterize the areas of pre-estuary seashores of 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 convective mixing process, and their content increases with depth.

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

In winter, a significant area of the Northern Caspian is covered with ice, but biochemical processes are actively developing in the under-ice water and ice. The ice of the Northern Caspian, being a kind of accumulator of biogenic substances, transforms these substances entering the sea from 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 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 summer, a redistribution of water is found in the waters of the Northern Caspian various forms 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.

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

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.

The main sources of pollutants, including oil products, entering the Caspian Sea are carry-over with river runoff, 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 the places where pollutants enter 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 with active volcanic activity (mud) in zone of oil and gas bearing structures.

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

The thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange and threatens the death of hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg/l, for phytoplankton - 0.1 mg/l.

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

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

arctic views. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire fauna of the Caspian (mysids, sea cockroach, white salmon, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna is crustaceans (71.4%), which easily tolerate desalination and live 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).

sea views. These are ciliates (386 forms), 2 species of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalves (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most unique brackish 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.

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The Caspian Sea is the world's largest endorheic body of water at a level of 28.5 m below the level of the World Ocean. The Caspian Sea stretches from north to south for almost 1200 km, the average width is 320 km, the length of the coastline is about 7 thousand km. The area of the Caspian Sea as a result of lowering the level decreased from 422 thousand km2 (1929) to 371 thousand km2 (1957). The volume of water is about 76 thousand km3, the average depth is 180 m. The coefficient of indentation of the coast is 3.36. The largest bays: Kizlyar, Komsomolets, Kara-Bogaz-Gol, Krasnovodsk, Mangyshlak.

There are about 50 islands with a total area of 350 km2. The most significant of them: Kulaly, Tyuleniy, Chechen, Zhiloy. More than 130 rivers flow into the Caspian Sea. The rivers Volga, Ural, Emba, Terek (total annual flow of 88% of the total river flow into the sea) flow into the northern part of the sea. On its western coast, the Sulak, Samur, Kura and other smaller rivers provide 7% of the total runoff. The remaining 5% of the flow is supplied by the rivers of the Iranian coast.

The relief of the bottom of the Caspian Sea

According to the nature of the underwater relief and the features of the hydrological regime in the Caspian Sea, the North, Middle and South Caspian are distinguished. The Northern Caspian (about 80,000 km2) is a shallow, slightly undulating, accumulative plain with prevailing depths of 4–8 capes. Within the Middle Caspian (138 thousand km2) shelf, continental slope and Derbent depression (maximum depth 788 m). The Apsheron threshold - a chain of banks and islands with depths of 170 m between them - limits the Middle Caspian from the south. The Southern Caspian (1/3 of the area of the sea) is distinguished by a very narrow shelf near the western and southern coasts and a much more extensive shelf near the eastern coast. In the depression of the South Caspian, the deepest sea depth of 1025 m was measured. The bottom of the depression is a flat abyssal plain.

Climate in the Caspian Sea

The main oaric centers that determine the atmospheric circulation over the Caspian Sea are: in winter - a spur of the Asian high, and in summer - the crest of the Azores high and the trough of the South Asian depression. Characteristic features of the climate are the predominance of anticyclonic weather conditions, dry winds, and sharp changes in air temperature.

In the northern and middle parts of the Caspian Sea, from October to April, the winds of the eastern quarter prevail, and from May to September, the winds of the northwestern rhumbs prevail. In the southern part of the Caspian Sea, the monsoon character of the winds is clearly expressed.

The long-term average air temperature of the warm months (July-August) over the entire sea is 24-26°C. The absolute maximum (up to 44°C) is noted on the east coast. On average, 200 mm of precipitation falls over the sea per year, with 90-100 mm on the arid eastern coast and 1700 mm in the subtropical southwestern part of the coast. Evaporation in most of the water area is about 1000 mm/year, and in the eastern part of the South Caspian and in the area of the Apsheron Peninsula up to 1400 mm/year.

Hydrological regime

The currents of the Caspian Sea are formed as a result of the combined effect of the wind regime, river runoff and density differences in individual areas. In the northern part of the Caspian Sea, the waters of the Volga River are divided into two branches. The smaller of them goes along the northern coast to the east, merges with the waters of the Ural River and forms a closed circulation. The main part of the waters of the Volga runoff goes along the western coast to the south. Somewhat to the north of the Absheron Peninsula, part of the waters of this current separates and, crossing the sea, goes to its eastern shores and flows into the waters moving to the north. Thus, in the Middle Caspian, a water cycle is formed, moving counterclockwise. The bulk of the waters spreading to the south. along the western coast, enters the South Caspian and, having reached the southern coast, turns to the east, and then along the eastern coasts goes to the north.
The speed of the currents is on average about 10–15 cm/s. The frequent recurrence of moderate and strong winds causes a large number of days with significant waves.

The maximum wave height (11 m) is observed in the area of the Apsheron threshold. The water temperature of the surface layer of the sea in August is about 24-26 ° C in the North and Middle Caspian, up to 29 ° C in the South, 32 ° C in the Krasnovodsk Bay and over 35 ° C in the Kara-Bogaz-Gol Bay. In July-August, upwelling and associated temperature drops to 8-10°C are observed off the eastern shores.

Ice formation in the northern part of the Caspian Sea begins in December, and the ice remains for 2–3 months. In cold winters, drifting ice is carried south to the Absheron Peninsula.
Isolation from the World Ocean, the influx of river waters and the precipitation of salts as a result of intense evaporation in the Kara-Bogaz-Gol Bay determine the peculiarity of the salt composition of the Caspian Sea water - a reduced content of chlorides and an increased concentration of carbonates in comparison with the waters of the World Ocean. The Caspian Sea is a brackish water basin, the salinity of which is three times less than the normal ocean.

The average salinity of the waters of the northwestern part of the Caspian Sea is 1-2 ppm, in the region of the northern border of the Middle Caspian 12.7-12.8 ppm, and in the South Caspian 13 ppm, the maximum salinity (13.3 ppm) is observed near the eastern shores. In the Gulf of Kara-Bogaz-Gol, the salinity is 300 ppm; In the Northern and Southern Caspian, due to the reduction in inflow and salinization during ice formation, salinity increases in winter. In the South Caspian at this time, salinity decreases due to a decrease in evaporation. In summer, an increase in river flow causes a decrease in the salinity of waters in the North and Middle Caspian, and increasing evaporation leads to an increase in the salinity of the waters of the South Caspian. Changes in salinity from the surface to the bottom are small. Therefore, seasonal fluctuations in temperature and salinity of water, causing an increase in density, determine the winter vertical circulation of water, which in the Northern Caspian extends to the bottom, and in the Middle Caspian to a depth of 300 m. in winter, the waters of the Middle Caspian through the Apsheron threshold and the sliding of cooled waters of high salinity from the eastern shallow water. Studies have shown that due to the increase in water salinity over the past 25 years, the mixing depth has significantly increased, the oxygen content has correspondingly increased, and hydrogen sulfide contamination of deep waters has disappeared.

Tidal fluctuations in the level of the Caspian Sea do not exceed 3 cm. about 0.7 m. The range of seasonal level fluctuations is about 30 cm. A characteristic feature of the hydrological regime of the Caspian Sea is sharp interannual fluctuations in the average annual level. The average level from zero of the Baku footstock for a century (1830-1930) was 326 cm. The highest level (363 cm) was observed in 1896. From 327 cm (1929), the level dropped to cm. In the last decade, the level of the Caspian Sea has stabilized at low levels with interannual fluctuations of the order of ±20 cm. Fluctuations in the level of the Caspian Sea are associated with climate changes over the entire basin of this sea.

To prevent a further drop in sea level, a system of measures is being developed. There is a project to transfer the waters of the northern rivers Vychegda and Pechora to the Volga river basin, which will increase the flow by about 32 km3. A project was developed (1972) to regulate the flow of Caspian waters into the Kara-Bogaz-Gol Bay.

Until now, there are disputes about the status of the Caspian Sea. The fact is that, despite its common name, it is still the largest endorheic lake in the world. It was called the sea because of the features that the structure of the bottom has. It is formed by oceanic crust. In addition, the water in the Caspian Sea is salty. As at sea, storms are often observed here and strong winds raising high waves.

Geography

The Caspian Sea is located at the crossroads of Asia and Europe. In its shape, it resembles one of the letters of the Latin alphabet - S. From south to north, the sea stretches for 1200 km, and from east to west - from 195 to 435 km.

The territory of the Caspian Sea is heterogeneous in terms of its physical and geographical conditions. In this regard, it is conventionally divided into 3 parts. These include the Northern and Middle, as well as the Southern Caspian.

coastal countries

Which countries are washed by the Caspian Sea? There are only five of them:

Russia, located in the northwest and west. The length of the coastline of this state along the Caspian Sea is 695 km. Kalmykia, Dagestan and the Astrakhan region, which are part of Russia, are located here.
Kazakhstan. This is a country on the shores of the Caspian Sea, located in the east and northeast. The length of its coastline is 2320 km.
Turkmenistan. The map of the Caspian states indicates that this country is located in the southeast of the water basin. The length of the line along the coast is 1200 km.
Azerbaijan. This state, stretching along the Caspian for 955 km, washes its shores in the southwest.
Iran. The map of the Caspian states indicates that this country is located on the southern shores of a drainless lake. At the same time, the length of its sea borders is 724 km.

Caspian sea?

Until now, the dispute about how to name this unique reservoir has not been resolved. And it is important to answer this question. The fact is that all countries on the Caspian Sea have their own interests in this region. However, the question of how to divide this huge body of water, the governments of the five states have not been able to decide for a long time. The main dispute revolved around the name. Is the Caspian still a sea or a lake? Moreover, the answer to this question is more of interest to non-geographers. First of all, politicians need it. This is due to the application of international law.

Caspian states such as Kazakhstan and Russia believe that their borders in this region are washed by the sea. In this regard, representatives of the two indicated countries insist on the application of the UN Convention, adopted in 1982. It concerns the law of the sea. The provisions of this document state that the coastal states are assigned a twelve-mile water zone along it. In addition, the country is granted the right to an economic maritime territory. It is located at a distance of two hundred miles. The coastal state also has the right to, however, even the widest part of the Caspian Sea is narrower than the distance specified in the international document. In such a case, the principle of the median line can be applied. At the same time, the Caspian states, which have the largest length of coastal borders, will receive a large sea area.

Iran has a different opinion on this matter. Its representatives believe that the Caspian should be divided fairly. In this case, all countries will get twenty percent of the sea area. One can understand the position of official Tehran. With such a solution to the problem, the state will control a larger zone than when dividing the sea along the median line.

However, the Caspian from year to year significantly changes its water level. This does not allow determining its median line and dividing the territory between states. Such countries of the Caspian Sea as Azerbaijan, Kazakhstan and Russia have signed an agreement among themselves defining those bottom zones on which the parties will exercise their economic rights. Thus, a certain legal truce has been achieved in the northern territories of the sea. The southern countries of the Caspian Sea have not yet come to a unified decision. At the same time, they do not recognize the agreements reached by their northern neighbors.

The Caspian is a lake?

Adherents of this point of view proceed from the fact that the reservoir, located at the junction of Asia and Europe, is closed. In this case, it is impossible to apply the document on the norms of international maritime law to it. Supporters of this theory are convinced that they are right, referring to the fact that the Caspian Sea has no natural connection with the waters of the World Ocean. But here another difficulty arises. If the lake is the Caspian Sea, the borders of states according to what international standards should be determined on its water spaces? Unfortunately, such documents have not yet been developed. The fact is that the issues of the international lake were not discussed anywhere and by anyone.

Is the Caspian a unique body of water?

In addition to those listed above, there is another, third point of view on the ownership of this amazing reservoir. Its supporters are of the opinion that the Caspian should be recognized as an international water basin, belonging equally to all countries bordering on it. In their opinion, the resources of the region are subject to joint exploitation by the countries bordering the reservoir.

Solving Security Issues

The Caspian states are doing everything possible to eliminate all existing differences. And there are positive developments in this regard. One of the steps towards solving problems related to the Caspian region was an agreement signed on November 18, 2010 between all five countries. It concerns issues of cooperation in the field of security. In this document, the countries agreed on joint activities to eliminate terrorism, drug trafficking, smuggling, poaching, money laundering, etc. in the region.

environmental protection

Particular attention is paid to solving environmental issues. The territory on which the Caspian states and Eurasia are located is a region under the threat of industrial pollution. Kazakhstan, Turkmenistan and Azerbaijan are dumping waste from exploration and production of energy carriers into the waters of the Caspian Sea. Moreover, it is in these countries that a large number of abandoned oil wells, which are not exploited because of their unprofitability, but nevertheless continue to have an adverse impact on the environmental situation. As for Iran, it dumps waste into sea waters Agriculture and stocks. Russia threatens the ecology of the region with industrial pollution. This is due to the economic activity that has unfolded in the Volga region.

Countries on the Caspian Sea have made some progress in solving problems environment. Thus, since August 12, 2007, the Framework Convection has been in force in the region, which sets itself the goal of protecting the Caspian Sea. This document developed provisions on the protection of bioresources and the regulation of anthropogenic factors affecting the aquatic environment. According to this convection, the parties must cooperate in carrying out activities to improve the environmental situation in the Caspian.

In 2011 and 2012, all five countries also signed other documents significant for the protection of the marine environment. Among them:

Protocol on Cooperation, Response and Regional Preparedness for Oil Pollution Events.
Protocol concerning the protection of the region against pollution from land-based sources.

Development of the gas pipeline construction

To date, another problem is unresolved in the Caspian region. It concerns the laying This idea is an important strategic task of the West and the United States, which continue to look for sources of energy resources alternative to Russian ones. That is why, when resolving this issue, the parties do not turn to such countries as Kazakhstan, Iran and, of course, the Russian Federation. Brussels and Washington supported the statement made in Baku on November 18, 2010 at the summit of the heads of the Caspian countries. He expressed the official position of Ashgabat regarding the laying of the pipeline. The Turkmen authorities believe that the project should be carried out. At the same time, only those states, on the territories of the bottom of which it will be located, must give their consent to the construction of the pipeline. These are Turkmenistan and Azerbaijan. Iran and Russia opposed this position and the project itself. At the same time, they were guided by the issues of protecting the Caspian ecosystem. To date, the construction of the pipeline is not carried out due to disagreement between the project participants.

Hosting the first summit

The countries on the Caspian Sea are constantly looking for ways to solve the problems that have matured in this Eurasian region. For this, special meetings of their representatives are organized. Thus, the first summit of the heads of the Caspian states took place in April 2002. Ashgabat became its venue. However, the results of this meeting did not meet expectations. The summit was considered unsuccessful due to Iran's demands for dividing the territory of the sea into 5 equal parts. This was strongly opposed by other countries. Their representatives defended their own point of view that the size of national water areas should correspond to the length that the coastline of the state has.

The failure of the summit was also provoked by a dispute between Ashgabat and Baku over the ownership of three oil fields located in the center of the Caspian Sea. As a result, the heads of the five states did not develop a unanimous opinion on any of all the issues raised. However, at the same time, an agreement was reached to hold a second summit. It was supposed to take place in 2003 in Baku.

Second Caspian Summit

Despite the existing agreements, the scheduled meeting was postponed every year. The heads of the Caspian littoral states gathered for the second summit only on October 16, 2007. The venue was Tehran. At the meeting, topical issues related to determining the legal status of a unique reservoir, which is the Caspian Sea, were discussed. The borders of the states within the framework of the division of the water area were preliminarily agreed during the development of the draft of the new convention. The problems of security, ecology, economy and cooperation of coastal countries were also raised. In addition, the results of the work that the states have carried out since the first summit were summed up. In Tehran, representatives of the five states also outlined ways for further cooperation in the region.

Meeting at the third summit

Once again, the heads of the Caspian countries met in Baku on November 18, 2010. The result of this summit was the signing of an agreement on expanding cooperation regarding security issues. During the meeting, it was pointed out that which countries werehes the Caspian Sea, only those should ensure the fight against terrorism, transnational crime, weapons proliferation, etc.

Fourth summit

Once again, the Caspian states raised their problems in Astrakhan on September 29, 2014. At this meeting, the presidents of the five countries signed another statement.

In it, the parties fixed the exclusive right of the coastal countries to deploy armed forces in the Caspian. But even at this meeting, the status of the Caspian was not finally settled.

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 in different time of the year)

The average water temperature in the Caspian in winter ranges from 0 °C in the northern part to +10 °C in the south. In the waters of Iran, the temperature does not fall below +13 °C. With the onset of cold weather, the shallow northern part of the lake is covered with ice, which lasts for 2-3 months. The thickness of the ice cover is 25-60 cm, at especially low temperatures it can reach 130 cm. 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 fish, pike perch, goby, grass carp, burbot, asp and pike perch. Stocks of sturgeon and salmon are currently depleted, however, the sea is the largest supplier of black caviar in the world.

Fishing in the Caspian Sea is allowed all year round except for the period from the end of April to the end of 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 spread out on the most picturesque Absheron peninsula and is surrounded on three sides by the waters of the warm and oil-rich Caspian Sea. Less big cities: the capital of Dagestan is Makhachkala, Kazakh Aktau, Turkmen Turkmenbashi and Iranian Bender-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.