Is the Caspian Sea a large salt lake. Water level fluctuations. Importance of the Caspian Sea

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:

1. 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.
2. 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.
3. 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.
4. Azerbaijan. This state, stretching along the Caspian for 955 km, washes its shores in the southwest.
5. Iran. The map of the Caspian states indicates that this country is located on the southern coast 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. Southern countries The Caspian Sea has 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, according to what international standards should the borders of states be defined in 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 are located, which are not operated because of their unprofitability, but nevertheless continue to have an adverse impact on the environmental situation. As for Iran, it dumps agricultural waste and sewage into the sea. Russia threatens the ecology of the region with industrial pollution. It's connected with economic activity deployed 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 interact when carrying out measures to improve 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 the division 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 coastline of the Caspian Sea is estimated at about 6500 - 6700 kilometers, with islands - up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low-lying and smooth. In the northern part, the coastline is indented by water streams and islands of the Volga and Ural deltas, the shores are low and swampy, and the water surface is covered with thickets in many places. The east coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding coasts are on the west coast in the area Absheron Peninsula and on the east coast in the area of ​​the Kazakh Gulf and Kara-Bogaz-Gol.

Peninsulas of the Caspian Sea

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

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

The largest islands:

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

Large bays of the Caspian Sea:

* Agrakhan Bay,
* Komsomolets (bay),
* Mangyshlak,
* Kazakh (bay),
* Turkmenbashi (Gulf) (former Krasnovodsk),
* Turkmen (bay),
* Gyzylagach,
* Astrakhan (Bay)
* Gyzlar
* Hyrcanus (former Astarabad) and
* Anzali (former Pahlavi).

Rivers flowing into the Caspian Sea

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

Caspian Sea Basin

The area of ​​the Caspian Sea basin is approximately 3.1 - 3.5 million square kilometers, which is approximately 10 percent of the world's closed water basins. The length of the Caspian Sea basin from north to south is about 2,500 kilometers, from west to east - about 1,000 kilometers. The Caspian Sea basin covers 9 states - Azerbaijan, Armenia, Georgia, Iran, Kazakhstan, Russia, Uzbekistan, Turkey and Turkmenistan.

coastal states

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

Cities on the coast of the Caspian Sea

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

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

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

Area, depth, volume of water

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

Water level fluctuations

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

Water temperature

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

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

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

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

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

Since there is no stable baroclinic layer in the Caspian Sea with a large potential energy reserve similar to the main thermocline of the World Ocean, with the cessation of the effect of the prevailing winds that cause upwelling, and with the onset of autumn-winter convection in October-November, the temperature fields are rapidly reorganized to the winter regime. In the open sea, the water temperature in the surface layer drops in the middle part to 12-13 °C, in the southern part to 16-17 °C. In the vertical structure, the shock layer is washed out due to convective mixing and disappears by the end of November.

Water composition

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

Mineralization in shallow saline bays-kultuks can reach 60-100 g/kg. In the Northern Caspian, during the entire ice-free period from April to November, a quasi-latitudinal salinity front is observed. The greatest desalination associated with the spread of river runoff over the sea area is observed in June. On the formation of salinity field in the Northern Caspian big influence renders the wind field. In the middle and southern parts sea ​​salinity fluctuations are small. Basically, it is 11.2-12.8 units. psu, increasing in the southern and eastern directions. Salinity increases insignificantly with depth (by 0.1–0.2 psu).

In the deep-water part of the Caspian Sea, in the vertical salinity profile, characteristic troughs of isohalines and local extrema are observed in the area of ​​the eastern continental slope, which indicate the processes of near-bottom creep of waters becoming saline in the eastern shallow waters of the South Caspian. The salinity value also strongly depends on the sea level and (which is interrelated) on the amount of continental runoff.

Bottom relief

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

Climate

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

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

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

currents

The circulation of water in the Caspian Sea is connected with the runoff and winds. Since most of the water flow falls on the Northern Caspian, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current is divided into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

Animal world

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

Vegetable world

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

Origin of the Caspian Sea

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

Anthropological and cultural history Caspian Sea

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

Exploration of the Caspian Sea

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

Mining of oil and gas

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

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

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

Shipping

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

Fishing and seafood

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

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and therapeutic mud in the coastal zone creates good conditions for rest and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast is noticeably losing Black Sea coast Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coast of Azerbaijan, Iran, Turkmenistan and Russian Dagestan.

Ecological problems

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

Border dispute over the status of the Caspian Sea

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

Coordinates: 42.622596 50.041848

The Caspian Sea is a brief description of the endorheic salt lake of Eurasia and the largest lake on the planet is given in this article. The information about the Caspian Sea will help you prepare for the lessons.

Caspian Sea: report

This water body is located at the geographical junction of Europe and Asia. The water level is 28 m below the level of the oceans. During its long history, the Caspian Sea has "changed" more than 70 names. And it got its modern name from the ancient tribe of the Caspians, who were engaged in horse breeding and settled along the southwestern shore of the lake.

Salinity of the Caspian Sea not constant: near the mouth of the Volga River, it is 0.05%, and in the southeast the figure increases to 13%. The area of ​​the water body today is about 371,000 km2, the maximum depth of the Caspian Sea is 1025 m.

Features of the Caspian Sea

Scientists conditionally divided the lake-sea into 3 natural zones:

• Northern
• Average
• Southern

Each of them has a different depth and composition of water. For example, the smallest part of the North. The full-flowing Volga River flows here, and therefore the salinity here is the lowest. And the southern part is the deepest, and, accordingly, salty.

The Caspian was formed more than 10 million years ago. It can be called part of the ancient super-ocean Tethys, which once ran between the African, Indian and Eurasian continental plates. Its long history is also evidenced by the nature of the bottom and geological coastal deposits. The length of the coastline is 6500 - 6700 km, and taking into account the islands up to 7000 km.

The shores of the Caspian Sea are predominantly smooth and low-lying. The northern part of the coastline is indented by islands and channels of the Ural and Volga deltas. The shore is swampy and low, covered with thickets. The east coast is characterized by limestone coasts that adjoin deserts and semi-deserts. The west and east coasts have winding coastlines.

Where does the Caspian Sea flow into?

Since the Caspian is an endorheic reservoir, it is logical that it does not flow anywhere. But 130 rivers flow into it. The largest of them are Terek, Volga, Emba, Ural, Kura, Atrek, Samur.

Climate of the Caspian

The climate is continental in the northern part of the sea, temperate in the middle part and subtropical in the southern part. In winter, the average temperature ranges from - 8 ... - 10 (northern part) to +8 ... + 10 (southern part). Summer average temperature ranges from +24 (northern part) to +27 (southern part). On the east coast, the maximum temperature was recorded - 44 degrees.

Animal and plant world

The fauna is diverse and includes 1809 species. 415 invertebrates, 101 species of fish live in the sea. It contains most of the world's reserves of pike perch, sturgeon, roach, carp. In the Caspian Sea there are carp, mullet, bream, sprat, perch, kutum, pike, as well as such a large mammal as the Caspian seal.

The flora is represented by 728 species. The sea is dominated by diatoms, brown, red, blue-green, charophytes, ruppia and zostera.

Importance of the Caspian Sea

On its territory there are many reserves of gas and oil, the deposits of which are at the development stage. Scientists have calculated that oil resources are 10 billion tons, and gas condensate - 20 billion tons. The first oil well was drilled in 1820 on the Absheron shelf. Limestone, sand, salt, stone, and clay are also mined on its shelf.

In addition, the Caspian Sea is popular among tourists. Modern resort zones are being created on its banks, mineral waters and mud contribute to the development of health centers and sanatoriums. The most famous resorts are Amburan, Nardaran, Zagulba, Bilgah.

Environmental problems of the Caspian Sea

The waters of the sea are polluted as a result of the extraction and transportation of gas and oil on the shelf. Pollutants also come from the rivers flowing into it. Poaching of sturgeon caviar led to a decrease in the number of these fish.

We hope that the report on the Caspian Sea helped you prepare for the lesson. And you can add an essay about the Caspian Sea through the comment form below.

, Kazakhstan, Turkmenistan, Iran , Azerbaijan

Geographical position

Caspian Sea - view from space.

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

The Caspian Sea is conditionally divided according to physical and geographical conditions into 3 parts - the North Caspian, the Middle Caspian and the South Caspian. The conditional border between the North and Middle Caspian runs along the line of about. Chechnya - Cape Tyub-Karagansky, between the Middle and South Caspian - along the line of about. Residential - Cape Gan-Gulu. The area of ​​the Northern, Middle and Southern Caspian is 25, 36, 39 percent respectively.

Coast of the Caspian Sea

Coast of the Caspian Sea in Turkmenistan

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

Peninsulas of the Caspian Sea

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

Bays of the Caspian Sea

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

Cities on the coast of the Caspian Sea

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

Physiography

Area, depth, volume of water

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

Water level fluctuations

Vegetable world

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

History of the Caspian Sea

Origin of the Caspian Sea

Anthropological and cultural history of the Caspian Sea

Finds in the Khuto cave near the southern coast of the Caspian Sea indicate that a person lived in these parts about 75 thousand years ago. The first mention of the Caspian Sea and the tribes living on its coast are found in Herodotus. Approximately in the V-II centuries. BC e. Saka tribes lived on the coast of the Caspian Sea. Later, during the period of the settlement of the Turks, in the period of the 4th-5th centuries. n. e. Talysh tribes (Talysh) lived here. According to ancient Armenian and Iranian manuscripts, the Russians sailed the Caspian Sea from the 9th-10th centuries.

Exploration of the Caspian Sea

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

Economy of the Caspian Sea

Mining of oil and gas

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

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

Shipping

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

Fishing and seafood

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

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and therapeutic mud in the coastal zone creates good conditions for recreation and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast noticeably loses to the Black Sea coast of the Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coast of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. The resort area in the Baku region is actively developing in Azerbaijan. At the moment, a world-class resort has been created in Amburan, another modern tourist complex is being built near the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also being developed in Nabran, in the north of Azerbaijan. However high prices, in general, the low level of service and the lack of advertising lead to the fact that on Caspian resorts almost not foreign tourists. The development of the tourism industry in Turkmenistan is hampered by a long policy of isolation, in Iran - Sharia law, due to which mass recreation foreign tourists on the Caspian coast of Iran is impossible.

Ecological problems

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

International status of the Caspian Sea

Legal status of the Caspian Sea

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Salinity. Salinity values ​​are determined by such factors as river runoff, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts of the Northern Caspian and between the Northern and Middle Caspian, the bottom topography, which determines the location of waters with different salinity, mainly along the isobaths, evaporation, which ensures the deficit fresh water and the influx of more salty. 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 deep sea trenches In the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of ​​the Apsheron threshold, where it is 1.6‰ in the surface layer and 2.1‰ at the 5 m horizon.

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

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

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

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

Ice formation. The Northern Caspian is covered with ice annually in November, the area of ​​the freezing part of the water area depends on the severity of the winter: in severe winters, the entire Northern Caspian is covered with ice, in soft ice it stays within the 2–3 meter isobath. The appearance of ice in the middle and southern parts of the sea falls on December-January. Near the eastern coast, ice is of local origin, near the western coast - most often brought from the northern part of the sea. In severe winters, shallow bays freeze off the eastern coast of the middle part of the sea, 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.

On the dynamics of concentrations nutrients during the year in the Caspian Sea are influenced by such factors as seasonal fluctuations in the biogenic runoff into the sea, the seasonal ratio of production-destruction processes, the intensity of the exchange between soil and water mass, ice conditions in winter time 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 that enter the sea with river runoff and from the atmosphere.

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

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

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

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

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

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. Total number autochthons - 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 on great depths The Middle and Southern Caspian (from 200 to 700 m), since the lowest water temperatures (4.9–5.9 ° C) are kept here throughout the year.

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

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

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

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