Southern coast of the Caspian Sea. Temperature and salinity. Vertical mixing of waters

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

The Caspian Sea has a vast drainage basin, with an area of ​​about 3.5 million km2. The nature of the landscapes, climatic conditions and types of rivers are different. Despite the vastness of the drainage basin, only 62.6% of its area is in wastewater areas; about 26.1% - for closed drainage. The area of ​​the Caspian Sea itself is 11.3%. 130 rivers flow into it, but almost all of them are located in the north and west (and the eastern bank 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 waters entering the sea (it should be noted that more than 25% of Russia's economy is located in the basin of this river, and this undoubtedly determines many hydrochemical and other features of the Caspian Sea waters), as well as rivers Kura, Zhaiyk (Ural), Terek, Sulak, Samur.

Physically and geographically and by the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional border between the northern and middle parts runs along the line of the Chechen island - the Tyub-Karagan cape, between the middle and the south - along the line of the Zhiloy island - Kuuli cape.
The shelf of the Caspian Sea is, on average, limited to a depth of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at a depth of 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, maximum depths of 15–20 m are located on the border with middle part seas. The bottom relief is complicated by the presence of banks, islands, grooves.
The middle part of the sea is a separate basin, the area 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 Apsheron sill, which is a continuation of the Greater Caucasus. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum depth of 1025 m for the sea is located east of the Kura delta. Several underwater ridges rise above the bottom of the basin, up to 500 m high.

The shores The Caspian Sea is diverse. In the northern part of the sea, they are rather strongly indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea - 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 west coast The Absheron Peninsula is located on the border with the southern part of the sea. To the east of it are the islands and banks of the Absheron archipelago, of which the largest is Zhiloy Island. The eastern coast of the Middle Caspian is more indented, here the Kazakh Gulf with Kenderli Bay and several capes stand out. The largest bay on this coast is Kara-Bogaz-Gol.

The islands of the Baku archipelago are located to the south of the Absheron Peninsula. The origin of these islands, as well as some of the cans near east coast the southern part of the sea is associated with the activity of underwater mud volcanoes lying on the bottom of the sea. On the east bank are located large bays Turkmenbashy and Turkmenian, and near the island of Ogurchinsky.

One of the most striking phenomena of the Caspian is the periodic variability of its level. In historical time, the Caspian Sea had a level lower than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) over the sea level, the amplitude of its fluctuations was 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 changed significantly twice. In 1929, it stood at about –26 m, and since it was close to this mark for almost a century, this level position was considered to be a mean annual or secular level. In 1930, the level began to decline rapidly. By 1941, it dropped by almost 2 m. This led to the drying up of vast coastal bottom areas. A decrease in the level, with its small fluctuations (short-term insignificant level rises in 1946-1948 and 1956-1958), continued until 1977 and reached -29.02 m, that is, the level took the lowest position in the 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 rose by more than 2 m. The rate of this rise is 15 cm per year. The increase in the level in some years was higher, and in 1991 it reached 39 cm.

The general fluctuations in the level of the Caspian Sea are superimposed on its seasonal changes, the mean multiyear of which reaches 40 cm, as well as on surges. The latter are especially pronounced in the North Caspian. The northwestern coast is characterized by large surges created by the prevailing storms of the eastern and southeastern directions, especially during the cold period of the year. A number of large (more than 1.5–3 m) surges have been observed here over the past decades. An especially 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 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, the winds of the eastern points prevail (the influence of the Asian maximum). The position in rather low latitudes provides a positive balance of heat inflow, therefore the Caspian Sea serves as a source of heat and moisture for the 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 - 11–14 ° С, in the southern part - 15–17 ° С. However, in the northernmost regions of the sea, the average January temperature is from –7 to –10 ° С, and the minimum during the invasions of the Arctic air is up to –30 ° С, which determines the formation of the ice cover. In summer, the entire region under consideration is dominated by rather high temperatures - 24–26 ° С. Thus, the North Caspian is subject to the sharpest 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 North Caspian Sea differs in this respect from the rest of the basin: here the average annual precipitation is less (for the western part, only 137 mm), and the distribution over the seasons is more even (10–18 mm per month). In general, we can talk about proximity climatic conditions to arid.
Water temperature. Distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, the nature of the bottom topography, isolation) have a certain impact on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be regarded 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 can be distinguished, separated by a transitional layer. In the North Caspian and in the surface layers of the Middle and South Caspian, the water temperature varies over a wide range. In winter, temperatures change from north to south from less than 2 to 10 ° С, the water temperature near the western coast is 1–2 ° С higher than that of the east, in the open sea the temperature is higher than at 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. In moderate and severe winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing point.

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

Salinity. Salinity values ​​are determined by such factors as river runoff, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts The North Caspian and between the North and Middle Caspian, bottom relief, which determines the location of waters with different salinity, mainly along isobaths, evaporation, providing a deficit fresh water and an influx of more salty ones. These factors collectively affect seasonal differences in salinity.
The North 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 middle Caspian waters directly flow. In this case, horizontal salinity gradients can reach 1 ‰ per 1 km.

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

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

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea waters, with runoff playing a decisive role. The intensification of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated water arriving in summer from the seashore is 10–15 ° C higher than that of the bottom water.
In the deep-water basins of the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5 ‰. The greatest difference between the maximum and minimum salinity was noted in the area of ​​the Absheron sill, 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 Kura river runoff. 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, there is a strip of desalinated waters with a salinity of 10–12.5 ‰ coming from the North Caspian.

In addition, in the South Caspian, an increase in salinity occurs when saline waters are carried out from bays and bays on the eastern shelf under the influence of southeastern winds. Later, 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-water part of the South Caspian, the upper boundary of waters with increased salinity drops to 250 m. It is obvious that in these parts of the sea, vertical mixing of waters is difficult.

Surface water circulation. The currents in the sea are mainly wind-driven. In the western part of the Northern Caspian, the currents of the western and eastern quarters are most often observed, in the eastern - southwestern and southern ones. The currents caused by the runoff of the Volga and Ural rivers are traced only within the estuarine seashore. The prevailing current velocities are 10–15 cm / s, in the open regions 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, in accordance with the directions of the wind, currents of the north-west, north, south-east and south directions are observed, along the east coast there are often currents east direction... Along the western coast of the middle part of the sea, the most stable currents are southeastern and southern. The velocities of the currents 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.

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

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

As a result of the winter vertical circulation of waters in the deep-water regions of the Middle and South 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 Northern 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). The high concentrations of ammonium and nitrate nitrogen, characteristic of the waters of a significant water area of ​​the Northern Caspian during floods, are due to intensive washing by the river waters of the Volga delta.

In the spring season, in the area of ​​water exchange between the North and Middle Caspian in the subsurface layer, at the maximum oxygen content, the phosphate content 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.

V summer time redistribution of various forms of biogenic compounds is found in the waters of the Northern Caspian. Here, the content of ammonium nitrogen and nitrates significantly decreases, 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 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, since there is an autumn outbreak of the development of diatoms.

More than 150 years on the shelf of the Caspian Sea oil.
Currently, large hydrocarbon reserves are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons of oil equivalent (of which 132 million tons of oil and 78 billion cubic meters of gas), on the shelf of the North Caspian - at 1 billion tons of oil ...
In total, about 2 billion tons of oil have already been produced in the Caspian Sea.
Losses of oil and 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 outflow with river runoff, the discharge of untreated industrial and agricultural wastewater, municipal wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, transportation of oil by sea. Places of entry of pollutants with river runoff are 90% concentrated in the Northern Caspian, industrial effluents are mainly confined to the area of ​​the Absheron Peninsula, and increased oil pollution of the South Caspian is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud volcanism) in the zone of oil and gas structures.

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

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

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

Arctic species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire fauna of the Caspian Sea (mysids, sea cockroach, white fish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna is made up of 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 are kept here throughout the year (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 mithielastr mollusk penetrated here, later 2 types of shrimp (with mullet, when acclimatized), 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 food supply for fish in the Caspian Sea.

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

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

The Caspian Sea provides over 80% of the world's sturgeon catches, the bulk of which is in the North Caspian.
To increase catches of sturgeon, which sharply decreased during the years of falling sea level, a set of measures is being carried out. Among them - a complete ban on fishing for sturgeon in the sea and its regulation in rivers, an increase in the scale of factory sturgeon breeding.

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

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

Why is the Caspian not considered a lake or a sea?

To be considered a sea, the Caspian must have access to the ocean, this is one of the most important conditions, according to which a body of water can be called a sea. But the Caspian does not have an outlet to the ocean, therefore it is considered a closed body of water, not connected to the World Ocean.

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

Due to the specific geographic and hydrological characteristics, the reservoir has received a special legal status. The summit participants made a decision according to which the Caspian is an inland water body that has no direct connection with the World Ocean, and therefore cannot be considered a sea, and at the same time, due to its size, water composition and bottom features, it cannot be considered a lake.

What has been achieved since the signing of the Convention?

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

“The most important thing that has been achieved is to fix that the Caspian will be demilitarized for all the Caspian states. There will be no other military personnel other than those representing the countries that signed the Caspian agreement. It is principled and main question, which was important to fix. Everything else, that which is divided in proportion to the zone of influence, zone of extraction of biological resources, zone of production of shelf resources was not so important. As we remember, in the past twenty years, the military has actively sought to the region. The United States even wanted to build its own military base", - says Martynov.

In addition to distributing the shares of each country in the oil and gas fields of the Caspian Basin, the Convention also provides for the construction of pipelines. As stated in the document, the rules for their laying provide for the consent of only neighboring countries, and not all countries of the Caspian Sea. After the signing of the agreement, Turkmenistan, in particular, announced that it was ready to lay pipelines along the seabed of the Caspian, which would allow it to export its gas through Azerbaijan to Europe. The consent of Russia, which previously insisted that the project could only be implemented with the permission of all five Caspian states, is no longer required. The gas pipeline is planned to be connected in the future to the Trans-Anatolian gas pipeline, through which natural gas will go through the territory of Azerbaijan, Georgia and Turkey to Greece.

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

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

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

The history of the emergence of the Caspian Sea?

The Sarmatian Sea existed on the planet 14,000,000 years ago. It consisted of the 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 to form four different seas.

The Caspian is inhabited by many representatives of the Azov fauna, 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 bore many names. It was called Derbent, Saraysky, Girkansky, Sigai, Kukkuz. Even in our time, for the inhabitants of Iran and Azerbaijan, this lake is called the Khazar lake.

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 maximum depth is about a thousand kilometers. The total area of ​​the reservoir is over 370,000 square kilometers and is divided into three climatic and geographical zones:

1. Northern
2. Average
3. South Caspian

The water area has six large peninsulas and about fifty islands. Their total area is four hundred square kilometers. Most large islands- Dzhambayskiy, Ogurchinskiy, Chechenya, Tyuleniy, Konevskiy, 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 Caspian Sea. But is this true?

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

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

The Caspian Sea received the right to be called a sea, first of all, because of its impressive size, which is more typical for seas than lakes. In terms of area, it surpasses even the Azov one. Also, not a small role was played by the fact that not a single lake washes the shores of five states at once.

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 World Ocean.

Compared to other seas, the percentage of salt saturation in it is very low 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 wave height can reach eleven meters. Storms can take place at any time of the year, but they are most dangerous in autumn and winter.

In fact, the Caspian Sea is the most big 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, not for seas.

The Caspian Sea has rich mineral resources such as oil and gas. Its waters are inhabited by over one hundred and twenty species of fish. Among them are the most valuable sturgeon, such as stellate sturgeon, sturgeon, sterlet, beluga, thorn. 90% of the world sturgeon catch is in the Caspian Sea.

Interesting features:

• Scientists all over the world have not come to an unambiguous opinion why the Caspian Sea is considered a lake. Some experts even propose to consider it a "lake-sea" or "inland" sea, like the Dead Sea in Israel;
• The most deep point The Caspian Sea - more than one kilometer;
• Historically, it is known that the total water level in a reservoir has changed more than once. The exact reasons for this have not yet been studied;
• It is the only body of water separating Asia and Europe;
• The largest waterway feeding 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 is inferior 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;
• Territory of Japan less area the Caspian Sea.

Ecological situation

Interference 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, there are frequent cases of poaching and illegal fishing of valuable fish species.

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 dropped by seven centimeters since 1996. By 2015, the level of the fall was about one and a half meters, and the water continues to fall.

If this continues further, 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 case of intensification of global warming, the process may accelerate and this will happen much earlier.

It is known that long before the start of global warming, the water level in the Caspian was undergoing changes. The water was standing and falling. Scientists still cannot say exactly for what reasons this happened.

The Caspian Sea is the largest closed body of water on the planet Earth, located on the continent of Eurasia - in the border territories of the states of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. In fact, it is a giant lake left after the disappearance of the ancient Tethys ocean. Nevertheless, there is every reason to consider it as an independent sea (this is indicated by salinity, a large area and decent depth, a bottom from the oceanic crust and other signs). In terms of maximum depth, it is the third among closed bodies of water - after lakes Baikal and Tanganyika. In the northern part of the Caspian Sea (a few kilometers from the northern coast - parallel to it) there is a geographical border between Europe and Asia.

• Other names: throughout the history of mankind, the Caspian Sea had about 70 different names among different peoples. The most famous of them: Khvalynskoe or Khvalisskoe (took place during Ancient Rus, originated from the name of the people praises who lived in the Northern Caspian Sea and traded with the Russians), Girkanskoe or Dzhurdzhanskoe (derived from the alternative names of the city of Gorgan, located in Iran), Khazar, Abeskunskoe (by the name of the island and the city in the Kura delta - now flooded), Saraisk, Derbent, Sihai ...
• Origin of name: according to one hypothesis, the Caspian Sea received its modern and most ancient name from a tribe of nomadic horse breeders Kaspiev living in 1st millennium BC on the southwest coast.

Morphometry

• Drainage area: 3,626,000 km².
• Mirror area: 371,000 km².
• Coastline length: 7,000 km
• Volume: 78 200 km³.
• Average depth: 208 m.
• Maximum depth: 1,025 m.

Hydrology

• The presence of a constant flow: no, drainless.
• Inflows:, Ural, Emba, Atrek, Gorgan, Heraz, Sefidrud, Astarchay, Kura, Pirsagat, Kusarchay, Samur, Rubas, Darvagchay, Uluchay, Shuraozen, Sulak, Terek, Kuma.
• Bottom: very diverse. At shallow depths, sandy soil with an admixture of shells is common, in deep-water places it is silty. Pebble and rocky places can be found in the coastal strip (especially where mountain ranges adjoin the sea). In the estuarine areas, the underwater soil consists of river sediments. The Kara-Bogaz-Gol bay is notable for the fact that its bottom is a thick layer of mineral salts.

Chemical composition

• Water: brackish.
• Salinity: 13 g / l.
• Transparency: 15 m.

Geography

Rice. 1. Map of the Caspian Sea Basin.

• Coordinates: 41 ° 59′02 ″ s. sh., 51 ° 03'52 ″ in. etc.
• Height above sea level:-28 m.
• Coastal landscape: due to the fact that the coastline of the Caspian Sea is very long, and it itself is located in different geographic areas- The coastal landscape is diverse. In the northern part of the reservoir, the shores are low, swampy, in places of the deltas of large rivers cut by numerous channels. The eastern shores are mostly limestone - desert or semi-desert. Western and south coast adjoin mountain ranges. The most indented coastline is observed in the west - in the area of ​​the Apsheron Peninsula, as well as in the east - in the area of ​​the Kazakh and Kara-Bogaz-Gol bays.
• Settlements on the banks:
  • Russia: Astrakhan, Derbent, Kaspiysk, Makhachkala, Olya.
  • Kazakhstan: Aktau, Atyrau, Kuryk, Sogandyk, Bautino.
  • Turkmenistan: Ekerem, Karabogaz, Turkmenbashi, Khazar.
  • Iran: Astara, Balboser, Bender-Torkemen, Bender-Anzali, Neka, Chalus.
  • Azerbaijan: Alat, Astara, Baku, Dubendi, Lankaran, Sangachaly, Sumgayit.

Ecology

The ecological situation in the Caspian Sea is far from ideal. Practically all large rivers flowing into it are polluted by wastewater from industrial enterprises located upstream. This could not but affect the presence of pollutants in the waters and bottom sediments of the Caspian - over the past half century, their concentration has significantly increased, and the content of some heavy metals has already exceeded the permissible limits.

In addition, the waters of the Caspian Sea are constantly polluted by domestic wastewater from coastal cities, as well as during oil production on the continental shelf, and during its transportation.

Fishing in the Caspian Sea

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• Artificial settlement: not all of the above fish species in the Caspian Sea are indigenous. About 4 dozen species were caught by accident (for example, through the channels from the Black and Baltic seas), or were deliberately inhabited by humans. An example is mullet. Three Black Sea species of these fish - striped mullet, ostronos and singil - were released in the first half of the 20th century. Loban did not take root, but the ostronos with the singil have successfully acclimatized, and by now they have settled practically throughout the entire water area of ​​the Caspian, having formed several commercial herds. At the same time, fish feed faster than in the Black Sea, and reach larger sizes. In the second half of the last century (since 1962), attempts were also made to settle in the Caspian Sea such Far Eastern salmon fishes as pink salmon and chum salmon. In total, several billion fry of these fish were released into the sea for 5 years. Pink salmon did not survive in the new range, chum salmon, on the contrary, successfully took root and even began to spawn in the rivers flowing into the sea. However, she could not reproduce in sufficient numbers and gradually disappeared. So far, there are no favorable conditions for its full-fledged natural reproduction (there are very few places where spawning and development of fry could successfully occur). To ensure them, reclamation of rivers is needed, otherwise, without human help (artificial sampling of eggs and its incubation), the fish will not be able to maintain their numbers.

Fishing spots

In fact, fishing is possible anywhere along the coast of the Caspian Sea, which can be reached by land or water. What species of fish will be caught at the same time depends on local conditions, but to a greater extent on whether rivers flow here. As a rule, in places where estuaries and deltas are located (especially large watercourses), the water in the sea is strongly desalinated, therefore freshwater fish (carp, catfish, bream, etc.) usually prevail in catches, and species characteristic of flowing rivers (barbel, shemaya). From marine species in desalinated areas, those for which salinity does not matter (mullet, some of the gobies) are caught. In certain periods of the year, semi-anadromous and anadromous species can be found here, feeding in the sea, and spawning in rivers (sturgeon, some of herring, Caspian salmon). In places where there are no rivers flowing in, freshwater species are found in slightly smaller numbers, but at the same time, marine fish appear, usually avoiding desalinated areas (for example, sea pike perch). Far from the coast, fish are caught, preferring salt water, and deep sea views.

In total, there are 9 places that are interesting in terms of fishing:

1. North Shore (RF)- this site is located on the northern coast of the Russian Federation (from the Volga delta to the Kizlyar Bay). Its main features are insignificant salinity of water (the lowest in the Caspian Sea), shallow depth, the presence of multiple shoals, islands, highly developed aquatic vegetation. In addition to the Volga delta with its numerous channels, bays and eriks, it also includes the near-estuarine seashore, called the Caspian peals. These places are popular with Russian fishermen, and for good reason: the conditions for fish are very favorable here, and there is also a good food base. The ichthyofauna in these parts may not be distinguished by the richness of species, but it is distinguished by its multiplicity, and its individual representatives reach very considerable sizes. Usually, the basis of catches is made up of freshwater fish characteristic of the Volga basin. Most often caught: perch, pike perch, roach (more precisely, its varieties, called roach and ram), rudd, asp, sabrefish, bream, goldfish, carp, catfish, pike. Bersh, silver bream, white-eyed, blue bream are somewhat less common. Representatives of sturgeon (sturgeon, stellate sturgeon, beluga, etc.), salmon (nelma, brown trout - Caspian salmon) are also found in these places, but their catch is prohibited.
2. Northwest coast (RF)- this section covers the west coast Russian Federation(from Kizlyar Bay to Makhachkala). The rivers Kuma, Terek and Sulak flow here - they carry their waters both along natural channels and artificial canals. There are bays in this area, some of which are quite large (Kizlyarsky, Agrakhansky). The sea in these places is shallow. Freshwater fish predominate in the catches: pike, perch, carp, catfish, rudd, bream, barbel, etc.
3. West Bank (RF)- from Makhachkala to the border of the Russian Federation with Azerbaijan. An area where mountain ranges adjoin the sea. The salinity of the water here is slightly higher than in previous places, therefore, in the catches of fishermen, marine species are more common (sea pike perch, mullet, herring). However, freshwater fish are by no means uncommon.
4. West Bank (Azerbaijan)- from the border of the Russian Federation with Azerbaijan along the Absheron Peninsula. Continuation of the site, where mountain ranges adjoin the sea. Fishing here is even more like a typical sea one, thanks to such fish as ostronos and singil (mullet) and several species of gobies, which are also caught here. In addition to them, there are kutum, herring, and some typically freshwater species, for example, the carp.
5. Southwest coast (Azerbaijan)- from the Absheron Peninsula to the border of Azerbaijan with Iran. Most This site is occupied by the Kura River delta. The same fish species that were listed in the previous paragraph are caught here, but freshwater ones are somewhat more common.
6. North coast (Kazakhstan)- this section covers the northern coast of Kazakhstan. The Ural delta and state reserve"Akzhaiyk", therefore, fishing directly in the river delta and in some adjacent water area is prohibited. Fishing is possible only outside the reserve - upstream of the delta, or in the sea - at some distance from it. Fishing near the Ural delta has a lot in common with fishing at the confluence of the Volga - almost the same species of fish are found here.
7. North-east coast (Kazakhstan)- from the mouth of the Emba to Cape Tyub-Karagan. In contrast to the northern part of the sea, where the water is greatly diluted by large rivers flowing into it, its salinity somewhat increases here, therefore those fish species appear that avoid freshened areas, for example, sea pike perch, which is caught in the Dead Kultuk Bay. Also, other representatives of the marine fauna are often found in the catches.
8. East coast (Kazakhstan, Turkmenistan)- from Cape Tyub-Karagan to the border of Turkmenistan and Iran. Differs in almost complete absence of flowing rivers. The salinity of the water is at its maximum here. Of the fish in these places, marine species predominate, the main catch is mullet, sea pike perch and gobies.
9. South Bank (Iran)- covers South coast Caspian. Along the entire length of this section, the Elburs mountain range adjoins the sea. Many rivers flow here, most of which are represented by small streams, there are also several medium and one large river. Of the fish, in addition to marine species, there are also some freshwater, as well as semi-anadromous and anadromous species, for example, sturgeon.

Fishing features

The most popular and catchy amateur tackle, which is used on the Caspian coast, is a heavy spinning rod converted into a "sea donkey". Usually it is equipped with a strong reel, on which a rather thick line (0.3 mm and more) is wound. The thickness of the line is determined not so much by the size of the fish as by the mass of a rather heavy sinker, which is necessary for ultra-long casting (in the Caspian it is generally believed that the further from the coast the casting point is, the better). After the sinker, there is a thinner line - with several leads. Shrimps and amphipods that live in coastal thickets of algae are used as a bait - if you intend to fish for sea fish, or an ordinary bait like a worm, May beetle larvae and others - if freshwater species are found in the fishing area.

, Terek, Kura

Geographical position

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

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

Coast

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

Peninsula

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

Islands

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

Gulfs

• Dead Kultuk (former Komsomolets, former Gulf of Tsesarevich)
• Kenderli
• Turkmenbashi (bay) (former Krasnovodsk)
• Turkmen (bay)
• Gizilagach (former Kirov Bay)
• Astrakhan (bay)
• Gyzlar
• Hyrcanus (formerly Astarabad)
• Anzali (formerly Pahlavi)

Kara-Bogaz-Gol

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

Rivers flowing into the Caspian Sea

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

Basin of the Caspian Sea

Coastal states

According to the Intergovernmental Economic Conference of the Caspian States:

The Caspian Sea washes the shores of five coastal states:

Cities on the coast of the Caspian Sea

On Russian coast cities are located - Lagan, Makhachkala, Kaspiysk, Izberbash, Dagestanskie Ogni and the southernmost city of Russia Derbent. Astrakhan is also considered the 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 the water level. With 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. 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 using the bathygraphic curve, is 208 meters. In the same time Northern part The Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

Vegetable world

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

History of the Caspian Sea

Origin of the Caspian Sea

The Caspian is of oceanic origin - its bed is composed of oceanic crust. 13 million years ago, the formed Alps separated the Sarmatian Sea from the Mediterranean. 3.4 - 1.8 million liters. n. (Pliocene) the Akchagyl Sea existed, the deposits of which were investigated by N.I. Andrusov. Originally formed on the site of the dried-up Pontic Sea, from which Balakhan Lake remained (on the territory southern Caspian). The Akchagyl Sea evolves into the Absheron Sea, which covers the Caspian and floods the territories of Turkmenistan and the Lower Volga region. After atelier regression (- 100 m) approx. 17 thousand liters n. the early Khvalynian transgression began - up to + 50 m (the Manych-Kerch Strait was functioning), which was replaced by the Elton regression. OK. 13.4-13.1 thousand liters. n. the Middle Khvalynian transgression began (0 m).

Anthropological and cultural history of the Caspian Sea

Shipping

Shipping is well developed in the Caspian Sea. On the Caspian Sea there are ferry crossings, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a navigable connection with the Sea of ​​Azov through the Volga, Don and Volga-Don Canal.

Fishing and seafood production

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

Recreational resources

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

Ecological problems

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

Legal status of the Caspian Sea

After the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of the 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,