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 and strong winds are often observed here, raising high waves.

Geography

Caspian Sea 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 shores of a drainless lake. However, its length maritime 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 this region own interests. 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. Regulations this document say that coastal states are assigned a twelve-mile water zone along it. In addition, the country is granted the right to economic maritime territory. It is located at a distance of two hundred miles. The coastal state also has the right to, however, even the widest part of the Caspian Sea is narrower than the distance specified in the international document. In such a case, the principle of the median line can be applied. At the same time, the Caspian states, which have the largest length of coastal borders, will receive a large sea area.

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

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

The Caspian is a lake?

Adherents of this point of view proceed from the fact that the reservoir, located at the junction of Asia and Europe, is closed. In this case, it is impossible to apply the document on the norms of international maritime law to it. Supporters of this theory are convinced that they are right, referring to the fact that the Caspian Sea has no natural connection with the waters of the World Ocean. But here another difficulty arises. If the lake is the Caspian Sea, 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 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 that are not operated due to 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 cooperate in carrying out activities to improve the environmental situation in the Caspian.

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

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

Development of the gas pipeline construction

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

Hosting the first summit

The countries on the Caspian Sea are constantly looking for ways to solve the problems that have matured in this Eurasian region. For this, special meetings of their representatives are organized. Thus, the first summit of the heads of the Caspian states took place in April 2002. Ashgabat became its venue. However, the results of this meeting did not meet expectations. The summit was considered unsuccessful due to Iran's demands for 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 coastline states.

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 are washed by the Caspian Sea, only those should ensure the fight against terrorism, transnational crime, weapons proliferation, etc.

Fourth summit

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

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

The Caspian Sea is the largest on Earth drainless lake, located at the junction of Europe and Asia, called the sea due to the fact that its bed is composed of an oceanic type of earth's crust. The Caspian Sea is a drainless lake, and the water in it is salty, from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data it was 27.16 m below sea level. The Caspian Sea is located at the junction of two parts of the Eurasian continent - Europe and Asia. The length of the Caspian Sea from north to south is about 1200 kilometers, from west to east - from 195 to 435 kilometers, an average of 310-320 kilometers. The Caspian Sea is conditionally divided according to physical and geographical conditions into 3 parts - the Northern Caspian, the Middle Caspian and the Southern 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.

The length of 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 channels 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 western coast near the Apsheron Peninsula and on the eastern coast near the Kazakh Gulf and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian Sea.

Bottom relief The relief of the northern part of the Caspian is a shallow undulating plain with banks and accumulative islands, the average depth of the Northern Caspian is 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. Temperature regime The water temperature is subject to significant latitudinal changes, most pronounced in winter, 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. The average water temperature at west coast 1-2 °C higher than that of the eastern one, and in the open sea the water temperature is 2-4 °C higher than that of the coasts.

Animal and plant 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 Sea, 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. The Caspian Sea is also inhabited by a marine mammal - the Caspian seal. 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 consciously or on the bottoms of ships.

Minerals 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.

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

The history of the appearance of the Caspian Sea?

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

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

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

Geographic location

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

• Turkmenistan
• Russia
• Azerbaijan
• Kazakhstan

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

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 major islands- Dzhambaysky, Ogurchinsky, Chechen, Tyuleniy, Konevsky, Zyudev and Apsheron Islands. About one hundred and thirty rivers flow into the Caspian, including the Volga, Ural, Atrek, Sefirud, Terek, Kura and many others.

Sea or lake?

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

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

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

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

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

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

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

In fact, the Caspian Sea is the 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, and not for seas.

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

Interesting features:

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

Ecological situation

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

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

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

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

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

The Caspian Sea is located in different geographical zones. It plays a big role in world history, is an important economic region and a source of resources. The Caspian Sea is a unique body of water.

Short description

This sea is large. The bottom is covered with oceanic bark. These factors make it possible to classify it as a sea.

It is a closed reservoir, has no drains and is not connected with the waters of the oceans. Therefore, it can also be attributed to the category of lakes. In this case, it will be the largest lake on the planet.

The approximate area of ​​the Caspian Sea is about 370 thousand square kilometers. The volume of the sea changes depending on the various fluctuations in the water level. The average value is 80 thousand cubic kilometers. The depth varies in its parts: the southern one has a greater depth than the northern one. The average depth is 208 meters, the highest value in the southern part exceeds 1000 meters.

Great role for development trade relations between the countries plays the Caspian Sea. The resources mined in it, as well as other trade items, were transported to different countries since the development of navigation at sea. Since the Middle Ages, merchants have delivered exotic goods, spices and furs. Today, in addition to transporting resources, ferries between cities are carried out by sea. The Caspian Sea is also connected by a navigable canal through the rivers with the Sea of ​​Azov.

Geographic characteristics

The Caspian Sea is located between two continents - Europe and Asia. Washes the territory of several countries. These are Russia, Kazakhstan, Iran, Turkmenistan and Azerbaijan.

It has more than 50 islands, both large and small in size. For example, the islands of Ashur-Ada, Tyuleniy, Chigil, Gum, Zenbil. As well as the peninsulas, the most significant - Absheron, Mangyshlak, Agrakhan and others.

The Caspian Sea receives the main influx of water resources from the rivers flowing into it. In total, there are 130 tributaries of this reservoir. The largest is the Volga River, which brings the bulk of the water. The Kheras, Ural, Terek, Astarchay, Kura, Sulak and many others rivers also flow into it.

The waters of this sea form many bays. Among the largest are: Agrakhansky, Kizlyarsky, Turkmenbashi, Girkan Bay. In the eastern part there is a bay-lake called Kara-Bogaz-Gol. It communicates with the sea by a small strait.

Climate

The climate is characterized geographical location sea, therefore, it has several types: from continental in the northern region to subtropical in the south. This affects the air and water temperatures, which have great contrasts depending on the part of the sea, especially in the cold season.

in winter average temperature air in the northern region is about -10 degrees, water reaches a value of -1 degree.

In the southern region, the temperature of air and water in winter warms up to an average of +10 degrees.

In summer, the air temperature in the northern zone reaches +25 degrees. Much hotter in the south. The maximum recorded value here is + 44 degrees.

Resources

Natural resources The Caspian Sea contains large reserves of various deposits.

One of the most valuable resources of the Caspian Sea is oil. Mining has been carried out since about 1820. Springs were opened on the territory of the seabed and its coast. By the beginning of the new century, the Caspian was at the forefront in obtaining this valuable product. During this time, thousands of wells were opened, which made it possible to extract oil on a huge industrial scale.

The Caspian Sea and the territory adjacent to it also have rich deposits natural gas, mineral salts, sand, lime, several types of natural clay and rocks.

Inhabitants and fisheries

The biological resources of the Caspian Sea are very diverse and highly productive. It contains more than 1500 species of inhabitants, rich in commercial fish species. The population depends on climatic conditions in different parts of the sea.

In the northern part of the sea, pike perch, bream, catfish, asp, pike and other species are more common. Gobies, mullet, bream, herring live in the western and eastern. Southern waters are rich in various representatives. One of the many are sturgeons. According to their content, this sea occupies a leading place among other reservoirs.

Among the wide variety, tuna, beluga, stellate sturgeon, sprat and many others are also caught. In addition, there are mollusks, crayfish, echinoderms and jellyfish.

The mammal Caspian seal lives in the Caspian Sea, or This animal is unique and lives only in these waters.

The sea is also characterized by a high content of various algae, for example, blue-green, red, brown; sea ​​grass and phytoplankton.

Ecology

The extraction and transportation of oil has a huge negative impact on the ecological situation of the sea. The ingress of oil products into water is almost inevitable. Oil stains cause irreparable damage to marine habitats.

The main inflow of water resources to the Caspian Sea is provided by rivers. Unfortunately, most of them have a high level of pollution, which degrades the quality of the water in the sea.

Industrial and domestic effluents from the surrounding cities are poured into the sea in large quantities, which also damages the environment.

Poaching causes great damage to the marine habitat. Sturgeon species are the main target for illegal catching. This significantly reduces the number of sturgeon and threatens the entire population of this type.

The above information will help to assess the resources of the Caspian Sea, to briefly study the characteristics and ecological situation of this unique reservoir.

CASPIAN SEA (Caspian), the world's largest enclosed body of water, drainless brackish lake. Located on the southern border of Asia and Europe, it washes the shores of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. Because of the size, originality natural conditions and complexity of hydrological processes The Caspian Sea is usually referred to the class of closed inland seas.

The Caspian Sea is located in a vast area of ​​internal flow and occupies a deep tectonic depression. The water level in the sea is at around 27 m below the level of the World Ocean, the area is about 390 thousand km 2, the volume is about 78 thousand km 3. The greatest depth is 1025 m. With a width of 200 to 400 km, the sea is elongated along the meridian for 1030 km.

The largest bays: in the east - Mangyshlak, Kara-Bogaz-Gol, Turkmenbashi (Krasnovodsk), Turkmen; in the west - Kizlyar, Agrakhan, Kyzylagadzh, Baku Bay; in the south - shallow lagoons. There are many islands in the Caspian Sea, but almost all of them are small, with total area less than 2 thousand km 2. In the northern part, there are numerous small islands adjacent to the Volga delta; larger ones - Kulaly, Morskoy, Tyuleniy, Chechen. Off the western shores - the Apsheron archipelago, to the south lie the islands of the Baku archipelago, near east coast- narrow, elongated from north to south island Ogurchinsky.

The northern shores of the Caspian Sea are low-lying and very sloping, characterized by a wide development of droughts formed as a result of surge phenomena; deltaic shores are also developed here (the deltas of the Volga, the Urals, and the Terek) with an abundant supply of terrigenous material; the Volga delta stands out with extensive reed beds. The western shores are abrasion, to the south of the Absheron Peninsula, mostly accumulative deltaic type with numerous bays and spits. southern shores base. The eastern shores are mostly deserted and low-lying, composed of sands.

Relief and geological structure of the bottom.

The Caspian Sea is located in a zone of increased seismic activity. In the city of Krasnovodsk (now Turkmenbashi) in 1895 there was a strong earthquake measuring 8.2 on the Richter scale. Eruptions of mud volcanoes are often observed on the islands and the coast of the southern part of the sea, leading to the formation of new shoals, banks and small islands, which are washed away by waves and reappear.

According to the peculiarities of physical and geographical conditions and the nature of the bottom topography in the Caspian Sea, it is customary to distinguish the Northern, Middle and Southern Caspian. The Northern Caspian is characterized by exceptional shallow water, located completely within the shelf with average depths of 4-5 m. Even small changes in the level here at low coasts lead to significant fluctuations in the area of ​​the water table, so the boundaries of the sea in the northeastern part on small-scale maps are shown by a dotted line. The greatest depths (about 20 m) are observed only near the conditional border with the Middle Caspian, which is drawn along the line connecting Chechen Island (to the north of the Agrakhan Peninsula) with Cape Tyub-Karagan on the Mangyshlak Peninsula. In the relief of the bottom of the Middle Caspian, the Derbent depression stands out (the greatest depth is 788 m). The boundary between the Middle and South Caspian passes over the Apsheron threshold with depths up to 180 m along the line from Chilov Island (to the east of the Absheron Peninsula) to Cape Kuuli (Turkmenistan). The basin of the South Caspian is the most extensive area of ​​the sea with the most great depths, almost 2/3 of the waters of the Caspian Sea are concentrated here, 1/3 falls on the Middle Caspian, less than 1% of the Caspian waters are located in the Northern Caspian due to shallow depths. In general, the shelf areas (the entire northern part and a wide strip along the eastern coast of the sea) predominate in the bottom relief of the Caspian Sea. The continental slope is most pronounced on the western slope of the Derbent Basin and almost along the entire perimeter of the South Caspian Basin. On the shelf, terrigenous-shell sands, shells, and oolitic sands are common; deep-water areas of the bottom are covered with silty and silty sediments with a high content of calcium carbonate. In some areas of the bottom, Neogene bedrocks are exposed. Mirabilite accumulates in the Ka-ra-Bogaz-Gol Bay.

In tectonic terms, within the Northern Caspian, there are southern part The Caspian syneclise of the East European platform, which is framed in the south by the Astrakhan-Aktobe zone, composed of Devonian-Lower Permian carbonate rocks, occurring on a volcanic base and containing large deposits of oil and natural combustible gas. Paleozoic folded formations of the Donets-Caspian zone (or the Karpinsky ridge) are pushed onto the syneclise from the southwest, which is a protrusion of the basement of the young Scythian (in the west) and Turan (in the east) platforms, which are separated at the bottom of the Caspian Sea by the Agrakhan-Guryev fault (left shift) of northeast strike. The Middle Caspian mainly belongs to the Turan platform, and its southwestern margin (including the Derbent depression) is a continuation of the Terek-Caspian foredeep of the folded system Greater Caucasus. The sedimentary cover of the platform and trough, composed of Jurassic and younger sediments, contains oil and combustible gas deposits in local uplifts. The Apsheron Sill, which separates the Middle Caspian from the South, is a connecting link of the Cenozoic folded systems of the Greater Caucasus and the Kopetdag. The South Caspian Basin of the Caspian Sea with crust of oceanic or transitional type is filled with a thick (over 25 km) complex of Cenozoic sediments. Numerous large hydrocarbon deposits are concentrated in the South Caspian Basin.

Until the end of the Miocene, the Caspian Sea was a marginal sea of ​​the ancient Tethys Ocean (since the Oligocene, the relic oceanic basin of the Paratethys). By the beginning of the Pliocene, it lost contact with the Black Sea. The Northern and Middle Caspians were drained, and the paleo-Volga valley stretched through them, the delta of which was located in the area of ​​the Apsheron Peninsula. Delta sediments have become the main reservoir of oil and natural combustible gas deposits in Azerbaijan and Turkmenistan. In the late Pliocene, due to the Akchagyl transgression, the area of ​​the Caspian Sea greatly increased and the connection with the World Ocean temporarily resumed. The waters of the sea covered not only the bottom of the modern depression of the Caspian Sea, but also the adjacent territories. In the Quaternary, transgressions (Absheron, Baku, Khazar, Khvalyn) alternated with regressions. The southern half of the Caspian Sea is located in a zone of increased seismic activity.

Climate. The Caspian Sea, strongly elongated from north to south, is located within several climatic zones. In the northern part, the climate is temperate continental, on the western coast - temperate warm, southwestern and south coast lie within the subtropics, on the east coast dominated by a desert climate. In winter, over the North and Middle Caspian, the weather is formed under the influence of the Arctic continental and sea air, and the South Caspian is often under the influence of southern cyclones. The weather in the west is unstable rainy, in the east it is dry. In summer, the western and northwestern regions are influenced by the spurs of the Azores atmospheric maximum, and the southeastern regions are influenced by the Iran-Afghan minimum, which together creates dry, stable warm weather. Winds of the north and northwest (up to 40%) and southeast (about 35%) directions prevail over the sea. The average wind speed is about 6 m/s, in central regions sea ​​up to 7 m/s, in the area of ​​the Apsheron Peninsula - 8-9 m/s. Northern storm "Baku Nords" reach speeds of 20-25 m/s. The lowest average monthly air temperatures of -10 °C are observed in January - February in the northeastern regions (in the most harsh winters reach -30 °С), in southern regions 8-12 °C. In July - August, the average monthly temperatures over the entire sea area are 25-26 °С, with a maximum of up to 44 °С on the east coast. The distribution of atmospheric precipitation is very uneven - from 100 mm per year on the eastern shores to 1700 mm in Lankaran. In the open sea, on average, about 200 mm of precipitation falls annually.

hydrological regime. Changes in the water balance of an enclosed sea strongly affect the change in the volume of water and the corresponding level fluctuations. Average long-term components of the water balance of the Caspian Sea for the 1900-90s (km 3 / cm layer): river runoff 300/77, precipitation 77/20, underground runoff 4/1, evaporation 377/97, ​​runoff in Kara-Bogaz- Goal 13/3, which forms a negative water balance of 9 km 3 or 3 cm layer per year. According to paleogeographic data, over the past 2000 years, the range of fluctuations in the level of the Caspian Sea has reached at least 7 m. -29 m (the lowest position in the last 500 years). The sea surface area has decreased by more than 40 thousand km 2, which exceeds the area Sea of ​​Azov. Since 1978, a rapid rise in level began, and by 1996 a mark of about -27 m relative to the level of the World Ocean was reached. In the modern era, fluctuations in the level of the Caspian Sea are determined mainly by fluctuations in climatic characteristics. Seasonal fluctuations in the level of the Caspian Sea are associated with the uneven flow of river flow (primarily the flow of the Volga), so the lowest level is observed in winter, the highest in summer. Short-term sharp level changes are associated with surge phenomena, they are most pronounced in shallow northern regions and can reach 3-4 m during storm surges. Such surges cause flooding of significant coastal land areas. In the Middle and Southern Caspian, surge fluctuations in the level are on average 10-30 cm, under storm conditions - up to 1.5 m. The frequency of surges, depending on the area, is from one to 5 times a month, the duration is up to one day. In the Caspian, as in any closed reservoir, seiche fluctuations in the level are observed in the form of standing waves with periods of 4-9 hours (wind) and 12 hours (tidal). The magnitude of seiche fluctuations usually does not exceed 20–30 cm.

River flow in the Caspian Sea is distributed extremely unevenly. More than 130 rivers flow into the sea, which, on average, bring about 290 km 3 of fresh water per year. Up to 85% of the river flow falls on the Volga with the Urals and enters the shallow Northern Caspian. The rivers of the western coast - Kura, Samur, Sulak, Terek, etc. - give up to 10% of the runoff. Another approximately 5% of fresh water is brought to the South Caspian by the rivers of the Iranian coast. The eastern desert shores are completely devoid of constant fresh water.

The average speed of wind currents is 15-20 cm/s, the highest - up to 70 cm/s. In the North Caspian, the prevailing winds create a flow directed along the northwestern coast to the southwest. In the Middle Caspian, this current merges with the western branch of the local cyclonic circulation and continues to move along the western coast. At the Absheron Peninsula, the current bifurcates. Its part in the open sea flows into the cyclonic circulation of the Middle Caspian, and the coastal part goes around the shores of the South Caspian and turns to the north, joining the coastal current, enveloping the entire eastern coast. The average state of the movement of the Caspian surface waters is often disturbed due to the variability of wind conditions and other factors. Thus, in the northeastern shallow area, a local anticyclonic gyre can occur. Two anticyclonic eddies are often observed in the South Caspian. In the Middle Caspian, during the warm season, steady northwest winds create southward transport along the east coast. In light winds and during calm weather, the currents may have other directions.

Wind waves develop very strongly, since the prevailing winds have a large acceleration length. The excitement develops mainly in the northwestern and southeastern directions. Severe storms are observed in the open waters of the Middle Caspian, in the areas of the city of Makhachkala, the Apsheron Peninsula and the Mangyshlak Peninsula. The average wave height of the greatest frequency is 1-1.5 m, at wind speeds of more than 15 m/s it increases to 2-3 m. 10 m

The water temperature on the sea surface in January - February in the North Caspian is close to freezing (about -0.2 - -0.3 ° C) and gradually increases in southbound up to 11 °C off the coast of Iran. In summer, surface waters warm up to 23-28 °С everywhere, except for the eastern shelf of the Middle Caspian, where seasonal coastal upwelling develops in July-August and the water temperature on the surface drops to 12-17 °С. In winter, due to intense convective mixing, the water temperature changes little with depth. In summer, under the upper heated layer at the horizons of 20-30 m, a seasonal thermocline (a layer of sharp temperature change) is formed, separating deep cold waters from warm surface waters. In the near-bottom layers of the waters of the deep-water depressions, the temperature is maintained all year round at 4.5-5.5 °C in the Middle Caspian and 5.8-6.5 °C in the South. The salinity in the Caspian Sea is almost 3 times lower than in the open areas of the World Ocean, and averages 12.8-12.9‰. It should be especially emphasized that the salt composition of the Caspian water is not completely identical to the composition of ocean waters, which is explained by the isolation of the sea from the ocean. The waters of the Caspian Sea are poorer in sodium salts and chlorides, but richer in calcium and magnesium carbonates and sulfates due to the unique composition of salts entering the sea with river and underground runoff. The highest salinity variability is observed in the Northern Caspian, where in the estuarine sections of the Volga and the Urals the water is fresh (less than 1‰), and as you move south, the salt content increases to 10-11‰ at the border with the Middle Caspian. The greatest horizontal salinity gradients are characteristic of the frontal zone between sea and river waters. Differences in salinity between the Middle and South Caspian are small, salinity slightly increases from northwest to southeast, reaching 13.6‰ in the Turkmen Gulf (up to 300‰ in Kara-Bogaz-Gol). Salinity changes along the vertical are small and rarely exceed 0.3‰, which indicates good vertical mixing of waters. Water transparency varies over a wide range from 0.2 m in the mouth areas of large rivers to 15-17 m in the central regions of the sea.

According to the ice regime, the Caspian Sea belongs to partially freezing seas. Ice conditions are observed annually only in the northern regions. The Northern Caspian is completely covered with sea ice, the Middle - partially (only in severe winters). Middle border sea ​​ice passes along an arc, turned by a bulge to the north, from the Agrakhan Peninsula in the west to the Tyub-Karagan Peninsula in the east. Usually, ice formation begins in mid-November in the extreme northeast and gradually spreads to the southwest. In January, the entire Northern Caspian is covered with ice, mostly landfast ice (fixed). Drifting ice borders the fast ice with a strip 20-30 km wide. The average thickness of ice is from 30 cm at the southern border to 60 cm in the northeastern regions of the Northern Caspian, in hummocky heaps - up to 1.5 m. The destruction of the ice cover begins in the 2nd half of February. In severe winters, drifting ice is carried to the south, along the western coast, sometimes as far as the Absheron Peninsula. In early April, the sea is completely free of ice cover.

Research history. It is believed that modern name The Caspian Sea comes from the ancient tribes of the Caspians, who inhabited the coastal regions in the 1st millennium BC; other historical names: Hyrkan (Irkan), Persian, Khazar, Khvalyn (Khvalis), Khorezm, Derbent. The first mention of the existence of the Caspian Sea dates back to the 5th century BC. Herodotus was one of the first to argue that this reservoir is isolated, that is, it is a lake. In the works of Arab scientists of the Middle Ages, there is information that in the 13-16 centuries the Amu Darya partially flowed into this sea by one of the branches. The well-known numerous ancient Greek, Arabic, European, including Russian, maps of the Caspian Sea until the beginning of the 18th century did not reflect reality and were in fact arbitrary drawings. By order of Tsar Peter I, an expedition was organized in 1714-15 under the leadership of A. Bekovich-Cherkassky, who explored the Caspian Sea, in particular its eastern shores. The first map, on which the contours of the coasts are close to modern ones, was compiled in 1720 using astronomical definitions by Russian military hydrographers F. I. Soymonov and K. Verden. In 1731, Soimonov published the first atlas, and soon the first printed sailing direction of the Caspian Sea. A new edition of the maps of the Caspian Sea with corrections and additions was carried out by Admiral A. I. Nagaev in 1760. The first information on the geology and biology of the Caspian Sea was published by S. G. Gmelin and P. S. Pallas. Hydrographic research in the 2nd half of the 18th century was continued by I.V. Tokmachev, M.I. Voinovich, at the beginning of the 19th century - by A.E. Kolodkin, who was the first to perform instrumental compass survey of the coast. Published in 1807 new map of the Caspian Sea, compiled taking into account the latest inventories. In 1837, systematic instrumental observations of sea level fluctuations began in Baku. In 1847 the first Full description Gulf of Kara-Bogaz-Gol. In 1878, the General Map of the Caspian Sea was published, which reflected the results of the latest astronomical observations, hydrographic surveys, and depth measurements. In 1866, 1904, 1912–13, and 1914–15, under the leadership of N. M. Knipovich, expeditionary studies were carried out in the hydrology and hydrobiology of the Caspian Sea; in 1934, a Commission for the Comprehensive Study of the Caspian Sea was established under the Academy of Sciences of the USSR. A great contribution to the study of the geological structure and oil content of the Apsheron Peninsula and the geological history of the Caspian Sea was made by Soviet geologists I. M. Gubkin, D. V. and V. D. Golubyatnikovs, P. A. Pravoslavlev, V. P. Baturin, S. A . Kovalevsky; in the study of water balance and sea level fluctuations - B. A. Appolov, V. V. Valedinsky, K. P. Voskresensky, L.S. Berg. After the Great Patriotic War, systematic diversified studies were launched in the Caspian Sea, aimed at studying the hydrometeorological regime, biological conditions and the geological structure of the sea.

In the 21st century, two large scientific centers are engaged in solving the problems of the Caspian Sea in Russia. Caspian Marine Research Center (KaspMNIC), established in 1995 by a government decree Russian Federation, conducts research work on hydrometeorology, oceanography and ecology. The Caspian Research Institute of Fisheries (CaspNIRKH) traces its history from the Astrakhan Research Station [established in 1897, since 1930 the Volga-Caspian Scientific Fisheries Station, since 1948 the Caspian Branch of the All-Russian Research Institute of Fisheries and Oceanography, since 1954 the Caspian Research Institute of Marine Fisheries and Oceanography (KaspNIRO), modern name since 1965]. CaspNIRKh is developing the foundations for the conservation and rational use of the biological resources of the Caspian Sea. It consists of 18 laboratories and scientific departments - in Astrakhan, Volgograd and Makhachkala. It has a scientific fleet of more than 20 vessels.

Economic use. The natural resources of the Caspian Sea are rich and varied. Significant hydrocarbon reserves are being actively developed by Russian, Kazakh, Azerbaijani and Turkmen oil and gas companies. There are huge reserves of mineral self-saddle salts in the Kara-Bogaz-Gol Bay. The Caspian region is also known as a massive habitat for waterfowl and near-water birds. About 6 million migratory birds migrate through the Caspian Sea every year. In this regard, the Volga delta, Kyzylagadzh, Northern Cheleken and Turkmenbashi bays are recognized as sites of international rank under the Ramsar Convention. The estuarine sections of many rivers flowing into the sea have unique types of vegetation. The fauna of the Caspian Sea is represented by 1800 animal species, of which 415 species are vertebrates. More than 100 species of fish live in the sea and estuaries of rivers. are of commercial importance sea ​​views- herring, sprat, gobies, sturgeons; freshwater - carp, perch; arctic "invaders" - salmon, white salmon. Major ports: Astrakhan, Makhachkala in Russia; Aktau, Atyrau in Kazakhstan; Turkmenbashi in Turkmenistan; Bandar Torkemen, Bandar Anzeli in Iran; Baku in Azerbaijan.

Ecological state. The Caspian Sea is under a powerful anthropogenic impact due to the intensive development of hydrocarbon deposits and the active development of fishing. In the 1980s, the Caspian Sea produced up to 80% of the world's sturgeon catch. Predatory catches of recent decades, poaching and a sharp deterioration in the ecological situation have put many valuable fish species on the brink of extinction. Habitat conditions have deteriorated not only for fish, but also for birds and marine animals (Caspian seal). The countries washed by the waters of the Caspian Sea are faced with the problem of creating a set of international measures to prevent pollution of the aquatic environment and developing the most effective environmental strategy for the near future. stable ecological state It is observed only in parts of the sea remote from the coast.

Lit.: Caspian Sea. M., 1969; Complex studies of the Caspian Sea. M., 1970. Issue. one; Gul K.K., Lappalainen T.N., Polushkin V.A. The Caspian Sea. M., 1970; Zalogin B. S., Kosarev A. N. Morya. M., 1999; International tectonic map of the Caspian Sea and its framing / Ed. V. E. Khain, N. A. Bogdanov. M., 2003; Zonn I. S. Caspian Encyclopedia. M., 2004.

M. G. Deev; V. E. Khain (geological structure of the bottom).