What is the Caspian Sea like? Rivers flowing into the Caspian Sea: list, description, characteristics. Environmental problems of the Caspian Sea
Is it correct to call the Caspian Sea a sea?
It is known that the sea is part of the World Ocean. From this geographically correct point of view, the Caspian Sea cannot in any way be considered a sea, since it is separated from the ocean by huge land masses. The shortest distance from the Caspian Sea to the Black Sea, the closest of the seas included in the World Ocean system, is 500 kilometers. Therefore, it would be more correct to talk about the Caspian Sea as a lake. This largest lake in the world is often called simply the Caspian or lake-sea.
The Caspian Sea has a number of characteristics of a sea: its water is salty (however, there are other salty lakes), its area is not much inferior to the area of such seas as the Black, Baltic, Red, Northern and even exceeds the area of the Azov and some others (however, the Canadian Lake Superior also has a huge area , like the three Seas of Azov). In the Caspian Sea there are often fierce storm winds and huge waves (and this is not uncommon on Lake Baikal).
So, after all, the Caspian Sea is a lake? That's Wikipedia says it And the Great Soviet Encyclopedia answers that no one has yet been able to give an exact definition of this issue - “There is no generally accepted classification.”
Do you know why this is very important and fundamental? And here's why...
The lake belongs to internal waters - the sovereign territories of coastal states, to which the international regime does not apply (the UN principle of non-interference in the internal affairs of states). But the sea area is divided differently, and the rights of coastal states here are completely different.
Due to its geographical location, the Caspian Sea itself, unlike the land territories surrounding it, has not been the object of any targeted attention from the coastal states for many centuries. Only at the beginning of the 19th century. the first treaties were concluded between Russia and Persia: Gulistan (1813) 4 and Turkmanchay (1828), summing up the results of the Russian-Persian war, as a result of which Russia annexed a number of Transcaucasian territories and received the exclusive right to maintain a military fleet in the Caspian sea. Russian and Persian merchants were allowed to trade freely on the territory of both states and use the Caspian Sea to transport goods. The Turkmanchay Treaty confirmed all these provisions and became the basis for maintaining international relations between the parties until 1917.
After the October Revolution of 1917, in a note dated January 14, 1918, the new Russian government that came to power renounced its exclusive military presence in the Caspian Sea. The treaty between the RSFSR and Persia of February 26, 1921 declared invalid all agreements concluded before it by the tsarist government. The Caspian Sea became a body of water for the common use of the parties: both states were granted equal rights of free navigation, with the exception of cases when the crews of Iranian ships could include citizens of third countries using the service for unfriendly purposes (Article 7). Treaty of 1921 maritime border did not provide between the parties.
In August 1935, the following agreement was signed, the parties to which were new subjects of international law - the Soviet Union and Iran, which acted under a new name. The parties confirmed the provisions of the 1921 agreement, but introduced into the agreement a new concept for the Caspian Sea - a 10-mile fishing zone, which limited the spatial limits of this fishery for its participants. This was done in order to control and preserve the living resources of the reservoir.
In the context of the outbreak of World War II, unleashed by Germany, an urgent need arose to conclude a new agreement between the USSR and Iran on trade and navigation in the Caspian Sea. The reason for this was the concern of the Soviet side, caused by Germany’s interest in intensifying its trade ties with Iran and the danger of using the Caspian Sea as one of the stages of the transit route. The agreement between the USSR and Iran 10 signed in 1940 protected the Caspian Sea from such a prospect: it repeated the main provisions of previous agreements, which provided for the presence of ships of only these two Caspian states in its waters. It also included a provision for its indefinite validity.
Camber Soviet Union radically changed the regional situation in the former Soviet space, in particular in the Caspian region. Among a large number of new problems, the problem of the Caspian Sea arose. Instead of two states - the USSR and Iran, which previously bilaterally resolved all emerging issues of maritime navigation, fishing and the use of other living and non-living resources, now there are five of them. Of the former, only Iran remained, Russia took the place of the USSR as successor, the other three are new states: Azerbaijan, Kazakhstan, Turkmenistan. They had access to the Caspian Sea before, but only as republics of the USSR, and not as independent states. Now, having become independent and sovereign, they have the opportunity to participate on equal terms with Russia and Iran in discussions and decision-making in considering all the issues mentioned above. This was also reflected in the attitude of these states towards the Caspian Sea, since all five states that had access to it showed equal interest in using its living and non-living resources. And this is logical, and most importantly, justified: the Caspian Sea is rich in natural resources, both fish stocks and black gold - oil and blue fuel - gas. Exploration and production of the last two resources became the subject of the most heated and protracted negotiations for a long time. But not only them.
In addition to the presence of rich mineral resources, the waters of the Caspian Sea are home to about 120 species and subspecies of fish; here is the global gene pool of sturgeon, the catch of which until recently accounted for 90% of the total world catch.
Due to its location, the Caspian Sea has traditionally and long been widely used for shipping, acting as a kind of transport artery between the peoples of the coastal states. Along its shores are located such large seaports as the Russian Astrakhan, the capital of Azerbaijan Baku, the Turkmen Turkmenbashi, the Iranian Anzeli and the Kazakh Aktau, between which routes for trade, cargo and passenger maritime transport have long been laid.
And yet, the main object of attention of the Caspian states is its mineral resources - oil and natural gas, which each of them can lay claim to within the boundaries that must be determined by them collectively on the basis of international law. And to do this, they will have to divide between themselves both the waters of the Caspian Sea and its bottom, in the depths of which its oil and gas are hidden, and develop rules for their extraction with minimal damage to a very fragile environment, especially the marine environment and its living inhabitants.
The main obstacle in resolving the issue of starting widespread mining of Caspian mineral resources for the Caspian states continues to be its international legal status: should it be considered a sea or a lake? The complexity of the issue lies in the fact that these states themselves must resolve it, and there is no agreement yet among them. But at the same time, each of them strives to quickly begin production of Caspian oil and natural gas and make their sale abroad a constant source of funds to form their budget.
Therefore, oil companies of Azerbaijan, Kazakhstan and Turkmenistan, without waiting for the end of the settlement of existing disagreements over the territorial division of the Caspian Sea, have already begun active production of its oil, in the hope of ceasing to be dependent on Russia, turning their countries into oil-producing countries and already in this capacity begin to build their own long-term trade relations with neighbors.
However, the issue of the status of the Caspian Sea remains unresolved. Regardless of whether the Caspian states agree to consider it a “sea” or a “lake”, they will have to apply the principles corresponding to the choice made to the territorial division of its water area and bottom or develop their own for this case.
Kazakhstan advocated recognition of the Caspian Sea by the sea. Such recognition will make it possible to apply the provisions of the 1982 UN Convention on the Law of the Sea on Internal Waters, the Territorial Sea, the Exclusive Economic Zone, and the Continental Shelf to the division of the Caspian Sea. This would allow coastal states to gain sovereignty over the subsoil of the territorial sea (Article 2) and exclusive rights to the exploration and development of resources on the continental shelf (Article 77). But the Caspian Sea cannot be called a sea from the standpoint of the 1982 UN Convention on the Law of the Sea, since this body of water is closed and has no natural connection with the world ocean.
In this case, the option of sharing its water area and bottom resources is also excluded.
In the agreements between the USSR and Iran, the Caspian Sea was considered as border lake. With the Caspian Sea being given the legal status of a “lake”, it is expected to be divided into sectors, as is done in relation to border lakes. But there is no norm in international law obliging states to do exactly this: division into sectors is an established practice.
The Russian Foreign Ministry has repeatedly made statements that the Caspian Sea is a lake, and its waters and subsoil are the common property of the coastal states. Iran also, from a position enshrined in treaties with the USSR, considers the Caspian Sea to be a lake. The government of the country believes that this status implies the creation of a consortium for unified management of the production and use of its resources Caspian states. Some authors also share this opinion, for example, R. Mamedov believes that with this status, the extraction of hydrocarbon resources in the Caspian Sea by these states should be carried out jointly.
In the literature, a proposal was made to give the Caspian Sea the status of a lake “sui generis”, and in this case we're talking about about the special international legal status such a lake and its special regime. A regime implies the joint development by states of their own rules for the use of its resources.
Thus, recognition of the Caspian Sea as a lake does not require its obligatory division into sectors - each coastal state has its own part. In addition, in international law there are no rules at all on the division of lakes between states: this is their good will, behind which certain internal interests may be hidden.
Currently, all Caspian states recognize that the modern legal regime was established by the established practice of its use, but now the Caspian Sea is in actual common use not by two, but by five states. Even at a meeting of foreign ministers held in Ashgabat on November 12, 1996, the Caspian states confirmed that the status of the Caspian Sea can be changed only with the consent of all five coastal states. This was later also confirmed by Russia and Azerbaijan in a joint statement dated January 9, 2001 on the principles of cooperation, as well as in the Declaration on Cooperation in the Caspian Sea signed between Kazakhstan and Russia dated October 9, 2000.
But during numerous Caspian negotiations, conferences and four summits of the Caspian states (Ashgabat summit on April 23-24, 2002, Tehran summit on October 16, 2007, Baku summit on November 18, 2010 and Astrakhan on September 29, 2014) agreement was reached by the Caspian countries failed to achieve this.
So far, cooperation at the bilateral and trilateral level has proven to be more productive. Back in May 2003, Russia, Azerbaijan and Kazakhstan entered into an agreement on the junction point of the demarcation lines of adjacent sections of the Caspian Sea bottom, which was based on previous bilateral agreements. In the current situation, Russia, by its participation in these agreements, seemed to confirm that the agreements between the USSR and Iran are outdated and do not correspond to existing realities.
In the Agreement of July 6, 1998 between the Russian Federation and the Republic of Kazakhstan on the delimitation of the bottom of the northern part of the Caspian Sea in order to exercise sovereign rights to subsoil use, it was announced that the seabed would be delimited between adjacent and opposite parties along a modified median line based on the principle of fairness and agreement of the parties. At the bottom of the site, states have sovereign rights, but their common use of the water surface is preserved.
Iran perceived this agreement as separate and in violation of previous Treaties with the USSR in 1921 and 1940. However, it should be noted that in the preamble of the 1998 agreement, to which Russia and Kazakhstan were parties, the agreement was considered as a temporary measure pending the signing of the convention by all Caspian states.
Later, on July 19 of the same year, Iran and Russia made a joint statement in which they proposed three possible scenarios for the delimitation of the Caspian Sea. First: the sea should be shared on the basis of the condominium principle. The second scenario comes down to dividing the water area, waters, bottom and subsoil into national sectors. The third scenario, which is a compromise between the first and second options, involves dividing only the bottom between the coastal states, and considering the water surface to be common and open to all coastal countries.
The existing options for delimiting the Caspian Sea, including those mentioned above, are possible only if there is good political will of the parties. Azerbaijan and Kazakhstan have clearly expressed their position from the very beginning of the multilateral consultation process. Azerbaijan considers the Caspian Sea to be a lake and therefore should be divided. Kazakhstan proposes to consider the Caspian Sea a closed sea, citing the 1982 UN Convention (Articles 122, 123), and, accordingly, advocates its division in the spirit of the Convention. Turkmenistan has long supported the idea of joint management and use of the Caspian Sea, but foreign companies already developing resources off the coast of Turkmenistan influenced the policies of its president, who began to object to the establishment of a condominium regime, supporting the position of dividing the sea.
The first of the Caspian states to begin to use the hydrocarbon riches of the Caspian Sea under new conditions was Azerbaijan. After the conclusion of the “Deal of the Century” in September 1994, Baku expressed a desire to declare the adjacent sector an integral part of its territory. This provision was enshrined in the Constitution of Azerbaijan, adopted in order to exercise sovereign rights to subsoil use, Moscow, July 6, 1998, at a referendum on November 12, 1995 (Article 11). But such a radical position from the very beginning did not correspond to the interests of all other coastal states, especially Russia, which has expressed fears that this would open access to the Caspian Sea to countries in other regions. Azerbaijan agreed to a compromise. The 2002 Agreement between the Russian Federation and Azerbaijan on the delimitation of adjacent areas of the Caspian Sea established a provision in which the division of the bottom was carried out using the median line, and the water area of the reservoir remained in joint use.
Unlike Azerbaijan, which has expressed a desire to completely divide the Caspian Sea, Iran proposes to leave its subsoil and water for joint use, but does not object to the option of dividing the Caspian Sea into 5 equal parts. Accordingly, each member of the Caspian Five would be allocated 20 percent of the total territory of the reservoir.
Russia's point of view was changing. Moscow has long insisted on establishing a condominium, but wanting to build a long-term policy with its neighbors, who were not interested in considering the Caspian Sea as the property of five coastal states, it changed its position. This then prompted the states to begin a new stage of negotiations, at the end of which the above Agreement was signed in 1998, where Russia stated that it was “ripe” for the division of the Caspian Sea. Its main principle was the position “common water - divide the bottom.”
Taking into account the fact that some Caspian states, namely Azerbaijan, Kazakhstan and Russia, have reached agreements on the conditional delimitation of spaces in the Caspian Sea, we can conclude that they are actually satisfied with the already established regime with the division of its bottom along a modified median line and the joint use of the surface reservoir for navigation and fishing.
However, the lack of complete clarity and unity in the position of all coastal countries prevents the Caspian states themselves from developing oil production. And oil is of key importance to them. There is no clear data regarding their reserves in the Caspian Sea. According to the US Energy Information Agency in 2003, the Caspian Sea ranked second in oil reserves and third in gas reserves. The data from the Russian side is different: they speak of an artificial overestimation by Western experts of the energy resources of the Caspian Sea. Differences in assessments are due to the political and economic interests of regional and external players. The geopolitical significance of the region, which is associated with the foreign policy plans of the US and the EU, became a factor in the distortion of the data. Zbigniew Brzezinski expressed the opinion back in 1997 that this region is the “Eurasian Balkans”.
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 in past geological eras it had connections with the ocean.
Today Russia has access only to the Northern Caspian Sea and the Dagestan part of the western coast of the Middle Caspian Sea. The waters of the Caspian Sea wash the shores of countries such as Azerbaijan, Iran, Turkmenistan, and Kazakhstan.
The sea area is 386.4 thousand km2, the volume of water is 78 thousand m3.
The Caspian Sea has a vast drainage basin, with an area of about 3.5 million km2. The nature of the landscapes, climatic conditions and types of rivers are different. Despite the vastness of the drainage basin, only 62.6% of its area is drainage areas; about 26.1% - for non-drainage. The area of the Caspian Sea itself is 11.3%. 130 rivers flow into it, but almost all of them are located in the north and west (and the eastern coast does not have a single river reaching the sea). Largest river the Caspian-Volga basin, which provides 78% of the river waters 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 the Kura River, Zhaiyk (Ural), Terek, Sulak, Samur.
Physiographically and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conventional border between the northern and middle parts runs along the line Chechen Island–Cape Tyub-Karagan, and between the middle and southern parts along the line Zhiloy Island–Cape Kuuli.
The shelf of the Caspian Sea is on average limited to depths of about 100 m. The continental slope, which begins below the shelf edge, ends in the middle part at approximately 500–600 m depths, 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 topography is complicated by the presence of banks, islands, and grooves.
The middle part of the sea is an isolated 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 by the Absheron threshold, which is a continuation Greater Caucasus. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression 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.
Shores The Caspian Sea is diverse. In the northern part of the sea they are quite indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy and Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islands and channels, often changing their position. Many small islands and banks are located in other areas coastline.
The middle part of the sea has a relatively flat coastline. On the western coast, on the border with the southern part of the sea, is the Absheron Peninsula. To the east of it there are islands and banks of the Absheron archipelago, of which the largest island is Zhiloy. The eastern coast of the Middle Caspian is more indented; the Kazakh Gulf with Kenderli Bay and several capes stand out here. The largest bay of this coast is Kara-Bogaz-Gol.
South of the Absheron Peninsula are the islands of the Baku archipelago. The origin of these islands, as well as some of the jars east coast the southern part of the sea is associated with the activity of underwater mud volcanoes lying on the seabed. On east coast There are large bays of 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 time The Caspian Sea had a level lower than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) of sea level, the amplitude of its fluctuations has been almost 4 m, from –25.3 m in the eighties of the 19th century. to –29 m in 1977. In the last century, the level of the Caspian Sea changed significantly twice. In 1929 it stood at about -26 m, and since it had been close to this level for almost a century, this level position was considered to be a long-term or secular average. In 1930 the level began to decline rapidly. By 1941 it had dropped by almost 2 m. This led to the drying out of vast coastal areas of the bottom. The decrease in level, with slight fluctuations (short-term slight rises in level in 1946–1948 and 1956–1958), continued until 1977 and reached a level of –29.02 m, i.e. the level reached its lowest position in history the last 200 years.
In 1978, contrary to all forecasts, sea level began to rise. As of 1994, the level of the Caspian Sea was at –26.5 m, that is, over 16 years the level rose by more than 2 m. The rate of this rise is 15 cm per year. The level increase 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 long-term average of which reaches 40 cm, as well as surge phenomena. The latter are especially pronounced in the Northern Caspian Sea. The northwestern coast is characterized by large surges created by prevailing storms from the eastern and southeastern directions, especially in the cold season. A number of large (more than 1.5–3 m) surges have been observed here over the past decades. 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 waters.
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Climate. The Caspian Sea is located in temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since the sea stretches from north to south for almost 1200 km.
Various atmospheric circulation systems interact in the Caspian region, however, winds from the eastern directions predominate throughout the year (the influence of the Asian High). The position at fairly low latitudes provides a positive balance of heat influx, 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°C, in the middle part - 11–14°C, in the southern part - 15–17°C. However, in the northernmost areas of the sea, the average January temperature is from –7 to –10°C, and the minimum during intrusions of Arctic air is down to –30°C, which determines the formation of ice cover. In summer, rather high temperatures dominate over the entire region under consideration - 24–26°C. Thus, the Northern Caspian is subject to the most dramatic temperature fluctuations.
The Caspian Sea is characterized by very a large number of precipitation per year is only 180 mm, with most of it occurring in 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 lower (for the western part only 137 mm), and the seasonal distribution is more uniform (10–18 mm per month). In general, we can talk about closeness climatic conditions to arid ones.
Water temperature. The distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, the nature of the bottom topography, isolation) have a certain influence on the formation of temperature conditions. In the shallow Northern Caspian Sea, the entire water column can be considered homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and Southern Caspian Sea, surface and deep masses can be distinguished, separated by a transition layer. In the Northern Caspian and in the surface layers of the Middle and Southern Caspian, water temperatures vary over a wide range. In winter, temperatures vary from north to south from less than 2 to 10°C, the water temperature off the west coast is 1–2°C higher than that on the east, in the open sea the temperature is higher than at the coasts: by 2–3°C in the middle part and by 3–4°С in the southern part of the sea. In winter, the distribution of temperature with depth is more uniform, which is facilitated by winter vertical circulation. During moderate and severe winters in the northern part of the sea and shallow bays of the east coast, the water temperature drops to freezing temperature.
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 Northern Caspian Sea. The zone where the lowest temperatures occur is adjacent to the east coast. This is explained by the rise of cold deep waters to the surface. Temperatures are also relatively low in the poorly heated deep-sea central part. In open areas of the sea, at the end of May–beginning of June, the formation of a temperature jump layer begins, which is most clearly expressed in August. Most often it is located between 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 off the eastern coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature throughout the year is about 4.5°C in the middle part and 5.8–5.9°C in the southern part.
Salinity. Salinity values are determined by factors such as river flow, 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, bottom topography, which determines the location of waters with different salinities, mainly along isobaths, evaporation providing a deficit fresh water and an influx of more salty ones. These factors collectively influence seasonal differences in salinity.
The Northern Caspian Sea 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 flow. Horizontal salinity gradients can reach 1‰ per 1 km.
The eastern part of the Northern Caspian Sea is characterized by a more uniform salinity field, since most of river and sea (Middle Caspian) waters enter this area of the sea in a transformed form.
Based on the values of horizontal salinity gradients, it is possible to distinguish in the western part of the Northern Caspian the river-sea contact zone with water salinity from 2 to 10‰, in the eastern part from 2 to 6‰.
Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea waters, the determining role is played by runoff. The strengthening 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 seashore in summer is 10–15°C higher than the bottom waters.
In the deep-sea depressions of the Middle and Southern Caspian Sea, fluctuations in salinity in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of the Absheron threshold, where it is 1.6‰ in the surface layer and 2.1‰ at a 5 m horizon.
The decrease in salinity along the western coast of the South Caspian Sea in the 0–20 m layer is caused by the flow of the Kura River. The influence of the Kura runoff decreases with depth; at horizons of 40–70 m, the range of salinity fluctuations is no more than 1.1‰. Along the entire western coast to the Absheron Peninsula there is a strip of desalinated water with a salinity of 10–12.5‰, coming from the Northern Caspian Sea.
In addition, in the Southern Caspian Sea, an increase in salinity occurs when salted waters are carried out from bays and gulfs on the eastern shelf under the influence of southeastern winds. Subsequently, these waters are transferred to the Middle Caspian Sea.
In the deep layers of the Middle and Southern Caspian Sea, the salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep-water part of the Southern Caspian, the upper limit of waters with high salinity drops to 250 m. Obviously, in these parts of the sea vertical mixing water is difficult.
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 part - southwestern and southern ones. Currents caused by the runoff of the Volga and Ural rivers can be traced only within the estuary coastal area. The prevailing current speeds are 10–15 cm/s; in open areas of the Northern Caspian Sea, maximum speeds are about 30 cm/s.
In the coastal areas of the middle and southern parts of the sea, in accordance with the wind directions, currents of the northwest, north, southeast and southern directions, off the east coast there are often easterly currents. Along the western coast of the middle part of the sea, the most stable currents are southeastern and southern. Current speeds are on average about 20–40 cm/s, with maximum speeds reaching 50–80 cm/s. Other types of currents also play a significant role in the circulation of sea waters: gradient, seiche, and inertial.
Ice formation. The Northern Caspian Sea is covered with ice every year in November, the area of the frozen part of the water area depends on the severity of the winter: in severe winters the entire Northern Caspian Sea is covered with ice, in mild winters the ice remains within 2–3 meter isobath. The appearance of ice in the middle and southern parts of the sea occurs in December-January. On the eastern coast the ice is of local origin, on the western coast it is 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, shores and fast ice form off the coast, and on the western coast, drifting ice spreads to the Absheron Peninsula in abnormally cold winters. The disappearance of ice cover is observed in the second half of February–March.
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Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of patterns. The central part of the waters of the Northern Caspian Sea is characterized by a fairly uniform distribution of oxygen. An increased oxygen content is found in the areas near the Volga River near the mouth, while a decreased oxygen content is found in the southwestern part of the Northern Caspian Sea. In the Middle and Southern Caspian highest concentrations oxygen are confined to coastal shallow areas and pre-estuary coastal areas of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.). In summer, due to the significant warming of water masses and the activation of photosynthesis processes, the leading factors in the formation of the oxygen regime are photosynthetic processes in surface waters, and biochemical oxygen consumption by bottom sediments in bottom waters. Thanks to high temperature water, stratification of the water column, a large influx of organic matter and its intense oxidation, oxygen is quickly consumed with minimal entry into the lower layers of the sea, as a result of which an oxygen deficiency zone is formed in the Northern Caspian Sea. Intensive photosynthesis in open waters The deep-sea regions of the Middle and Southern Caspian Sea cover the upper 25-meter layer, where oxygen saturation is more than 120%. |
– The Northern Caspian, which is a vast mixing zone of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
– in the Middle Caspian, the cyclonic nature of the circulation contributes to the rise of deep waters with a high content of nutrients into the overlying layers of the sea;
– in the deep-water regions of the Middle and Southern Caspian Sea, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.
On the dynamics of concentrations nutrients During the year, the Caspian Sea is influenced by such factors as seasonal fluctuations in nutrient runoff into the sea, the seasonal ratio of production-destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter time in the Northern Caspian, processes of winter vertical circulation in deep-water areas of the sea.
In winter, a significant area of the Northern Caspian Sea is covered with ice, but biochemical processes actively develop in subglacial water and in ice. The ice of the Northern Caspian Sea, being a kind of accumulator of nutrients, transforms these substances entering the sea with river runoff and from the atmosphere.
As a result of the winter vertical circulation of water in the deep-water regions of the Middle and Southern Caspian Sea during the cold season, the active layer of the sea is enriched with nutrients due to their supply from the underlying layers.
Spring for the waters of the Northern Caspian Sea 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 Sea during floods, are due to intensive washing by river waters of the Volga delta.
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In the spring season, in the area of water exchange between the Northern and Middle Caspian Seas in the subsurface layer, with a maximum oxygen content, the phosphate content is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.
In the Southern 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 detected. Here the content of ammonium nitrogen and nitrates decreases significantly, 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 Southern Caspian Sea, the concentration of phosphates has decreased due to their consumption during photosynthesis and the difficulty of water exchange with the deep-sea accumulation zone.
In autumn in the Caspian Sea, due to the cessation of activity of some types of phytoplankton, the content of phosphates and nitrates increases, and the concentration of silicon decreases, as there is an autumn outbreak of the development of diatoms.
For more than 150 years, oil has been mined on the shelf of the Caspian Sea. oil.
Currently, large hydrocarbon reserves are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons in oil equivalent (of which 132 million tons of oil and 78 billion m3 of gas), on the shelf of the Northern Caspian Sea - at 1 billion tons of oil .
In total, about 2 billion tons of oil have already been produced in the Caspian Sea.
Losses of oil and its products during production, transportation and use reach 2% of the total volume.
Main sources of income pollutants, including petroleum products into the Caspian Sea - this is the removal with river runoff, the discharge of untreated industrial and agricultural wastewater, municipal wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, oil transportation by sea. The places where pollutants enter with river runoff are 90% concentrated in the Northern Caspian Sea, industrial wastes are confined mainly to the area of the Absheron Peninsula, and increased oil pollution of the Southern Caspian Sea is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud volcanism) in the zone of oil and gas bearing structures.
From the territory of Russia, about 55 thousand tons of petroleum products enter the Northern Caspian annually, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the runoff of the Terek and Sulak rivers.
Thickening of the film on the water surface to 0.01 mm disrupts gas exchange processes and threatens the death of hydrobiota. The concentration of petroleum products is toxic to fish at 0.01 mg/l and to phytoplankton at 0.1 mg/l.
The development of oil and gas resources on the bottom of the Caspian Sea, the forecast reserves of which are estimated at 12–15 billion tons of standard fuel, will become the main factor in the anthropogenic load on the sea ecosystem in the coming decades.
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Caspian autochthonous fauna. The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, mollusks, etc.
Arctic species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire Caspian fauna (mysids, sea cockroach, whitefish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna are crustaceans (71.4%), which easily tolerate desalination and live at great depths of the Middle and Southern Caspian Sea (from 200 to 700 m), since the lowest water temperatures are maintained here throughout the year (4.9– 5.9°C).
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Mediterranean species. These are 2 types of mollusks, needle fish, etc. At the beginning of the 20s of our century, the mollusk mytileaster entered here, later 2 types of shrimp (with mullet, during their acclimatization), 2 types of mullet and flounder. Some Mediterranean species entered the Caspian Sea after the opening of the Volga-Don Canal. Mediterranean species play a significant role in the food supply of fish in the Caspian Sea.
Freshwater fauna(228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, carp, and also rotifers).
Marine species. These are ciliates (386 forms), 2 species of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalves (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most unique brackish bodies of water on the planet.
The Caspian Sea produces more than 80% of the world's sturgeon catches, the bulk of which occur in the Northern Caspian Sea.
To increase sturgeon catches, which sharply decreased during the years of falling sea levels, a set of measures is being implemented. Among them are a complete ban on sturgeon fishing in the sea and its regulation in rivers, and an increase in the scale of sturgeon factory farming.
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The territory of Russia is washed by twelve seas belonging to the basins three oceans. But one of these seas - the Caspian - is often called a lake, which sometimes confuses people who have little understanding of geography.
Meanwhile, it is really more correct to call the Caspian a lake rather than a sea. Why? Let's figure it out.
A little geography. Where is the Caspian Sea located?
Occupying an area that exceeds 370,000 square kilometers, the Caspian Sea stretches from north to south, dividing its water surface spaces of Europe and Asia. Its coastline belongs to five different countries: Russia, Kazakhstan, Azerbaijan, Turkmenistan and Iran. Geographers conventionally divide its water area into three parts: the Northern (25% of the area), the Middle (36% of the area) and the Southern Caspian (39% of the area), which differ in climate, geological conditions and natural features. The coastline is predominantly flat, indented by river channels, covered with vegetation, and in the northern part, where the Volga flows into the Caspian Sea, it is also swampy.
The Caspian Sea has about 50 large and small islands, about one and a half dozen bays and six large peninsulas. In addition to the Volga, approximately 130 rivers flow into it, and nine rivers form fairly wide and branched deltas. The annual drainage of the Volga is about 120 cubic kilometers. Together with other large rivers - Terek, Ural, Emba and Sulak - this accounts for up to 90% of the total annual flow into the Caspian Sea.
Why is the Caspian called a lake?
The main feature of any sea is the presence of straits connecting it to the ocean. The Caspian Sea is a closed or closed reservoir that receives river water, but is not connected to any ocean. 
Its water contains a very small amount of salt compared to other seas (about 0.05%) and is considered slightly salty. Due to the absence of at least one strait connecting to the ocean, the Caspian Sea is often called the largest lake in the world, since the lake is a completely enclosed body of water, which is fed only river water.
The waters of the Caspian Sea are not subject to international maritime laws, and its waters are divided between all countries that are adjacent to it, in proportion to the coastline.
Why is the Caspian called a sea?
Despite all of the above, most often in geography, as well as in international and internal documents, the name “Caspian Sea” is used, and not “Caspian Lake”. First of all, this is explained by the size of the reservoir, which is much more typical for the sea than for the lake. Even, which is much smaller in area than the Caspian Sea, local residents often called the sea. There are no other lakes in the world whose shores belong simultaneously to five different countries.
In addition, you should pay attention to the structure of the bottom, which near the Caspian Sea has a pronounced oceanic type. Once upon a time, the Caspian Sea most likely connected with the Mediterranean, but tectonic processes and drying out separated it from the World Ocean. There are more than fifty islands in the Caspian Sea, and the area of some of them is quite large, even by international standards they are considered large. All this allows us to call the Caspian a sea, and not a lake.
origin of name
Why is this sea (or lake) called the Caspian? The origin of any name is often associated with ancient history terrain. Different peoples who lived on the shores of the Caspian called it differently. More than seventy names of this reservoir have been preserved in history - it was called the Hyrcanian, Derbent, Sarai Sea, etc. 
Iranians and Azerbaijanis still call it the Khazar Sea. It began to be called Caspian after the name of the ancient tribe of nomadic horse breeders who lived in the steppes adjacent to its coast - the numerous Caspian tribe. They gave it its name large lake on our planet - the Caspian Sea.
The coastline of the Caspian Sea is estimated at approximately 6,500 - 6,700 kilometers, with islands - up to 7,000 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 banks are low and swampy, and the water surface in many places is covered with thickets. The east coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding shores are on the western coast in the area of the Absheron Peninsula and on the eastern 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
* The Absheron Peninsula, located on the western coast of the Caspian Sea on the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory the cities of Baku and Sumgait are located
* 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 total area approximately 350 square kilometers.
Most large islands:
* Ashur-Ada
* Garasu
*Hum
* Dash
* Zira (island)
* Zyanbil
* Cure Dasha
* Khara-Zira
* Sengi-Mugan
* Chechen (island)
* Chygyl
Large bays of the Caspian Sea:
* Agrakhan Bay,
* Komsomolets (bay),
* Mangyshlak,
* Kazakh (bay),
* Turkmenbashi (bay) (formerly Krasnovodsk),
* Turkmen (bay),
* Gizilagach,
* Astrakhan (bay)
* Gyzlar
* Hyrcanus (formerly Astarabad) and
* Anzeli (formerly Pahlavi).
Rivers flowing into the Caspian Sea
130 rivers flow into the Caspian Sea, of which 9 rivers have a delta-shaped mouth. 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. The largest river flowing into the Caspian Sea is the Volga, its average annual flow is 215-224 cubic kilometers. The Volga, Ural, Terek and Emba provide up to 88 - 90% of the annual runoff of the Caspian Sea.
Basin of the Caspian Sea
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 basin area. The length of the Caspian Sea basin from north to south is about 2500 kilometers, from west to east - about 1000 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, coastline length 695 kilometers
* Kazakhstan - in the north, northeast and east, coastline length 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, coastline length 955 kilometers
Cities on the Caspian Sea coast
The largest city and port on the Caspian Sea is Baku, the capital of Azerbaijan, which is located in the southern part of the Absheron Peninsula and has a population of 2,070 thousand people (2003). Other large Azerbaijani Caspian cities are Sumgait, which is located in the northern part of the Absheron Peninsula, and Lankaran, which is located near southern border Azerbaijan. To the South-East of the Absheron Peninsula, the oil workers’ village of Neftyanye Kamni is located, the buildings of which stand on artificial islands, overpasses and technological sites.
Large Russian cities- the capital of Dagestan Makhachkala and the most Southern City Russia Derbent - located on the western coast of the Caspian Sea. 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 north coast Caspian Sea.
On the eastern shore of the Caspian Sea there is a Kazakh city - the port of Aktau, in the north in the Ural delta, 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, former Krasnovodsk. Several Caspian cities are located on the southern (Iranian) coast, the largest of them is Anzeli.
Area, depth, volume of water
The area and volume of water of 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 in Northern part The Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.
Water level fluctuations
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 been 15 meters. Instrumental measurements of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out since 1837, during which 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 risen and in 1995 reached −26.7 m; since 1996, there has again been a downward trend in the level of the Caspian Sea. Scientists associate the reasons for 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, when the temperature varies 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 difference in water temperature 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 off the western coast is 1-2 °C higher than that on the eastern coast, and in the open sea the water temperature is 2-4 °C higher than on the coasts. Based on the nature of the horizontal structure of the temperature field in the annual cycle of variability, three can be distinguished: time intervals in the upper 2-meter layer. From October to March, the water temperature increases in the southern and eastern regions, which is especially clearly visible in the Middle Caspian. Two stable quasi-latitudinal zones can be distinguished, where temperature gradients are increased. This is, firstly, the border between the Northern and Middle Caspian, and, secondly, between the Middle and Southern. 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 Absheron threshold, from 7 to 10 °C. During this period, the least cooled waters are in the center of the South Caspian Sea, which form a quasi-stationary core.
In April-May, the area of minimum temperatures moves to the Middle Caspian Sea, which is associated with faster heating 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 here rises to 16-17 °C. In the middle part the temperature at this time is 13-15 °C, and in the south it increases to 17-18 °C.
Spring warming of water evens out horizontal gradients, and the temperature difference between coastal areas and open sea does not exceed 0.5 °C. Warming up of the surface layer, starting in March, disrupts the homogeneity in the temperature distribution with depth. In June-September, horizontal homogeneity in the temperature distribution in the surface layer is observed. In August, which is the month of greatest warming, the water temperature throughout the sea is 24-26 °C, and in the southern regions it 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 Southern Caspian.
The rise of cold deep waters occurs with varying intensity as a result of the influence of prevailing summer season northwest winds. The wind in this direction causes the outflow of warm surface waters from the coast and the rise of colder waters from the intermediate layers. Upwelling begins in June, but it reaches its greatest intensity in July-August. As a result, a decrease in temperature is observed on the surface of the water (7-15 °C). Horizontal temperature gradients reach 2.3 °C at the surface and 4.2 °C at a depth of 20 m.
The source of upwelling gradually shifts from 41-42° north. latitude in June, to 43-45° north. latitude in September. Summer upwelling is of great importance for the Caspian Sea, radically changing the dynamic processes in the deep-water area. In 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 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 off the eastern coast, the shock layer rises close to the surface.
Since the Caspian Sea lacks a stable baroclinic layer with large supply potential energy similar to the main thermocline of the World Ocean, then with the cessation of the prevailing winds causing upwelling and with the beginning of autumn-winter convection in October-November, a rapid restructuring of the temperature fields to the winter regime occurs. 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 eroded 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 the oceanic one. There are significant differences in the ratios of concentrations of salt-forming ions, especially for waters in areas directly influenced by 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 of 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 ions. In the Caspian Sea, the content of calcium and magnesium cations is almost two times higher than in the Sea of Azov, and the sulfate anion is three times higher. The salinity of water changes especially sharply in the northern part of the sea: from 0.1 units. psu in the estuary areas of the Volga and Ural up to 10-11 units. psu on the border with the Middle Caspian.
Mineralization in shallow salty bays-kultuks can reach 60-100 g/kg. In the Northern Caspian, during the entire ice-free period from April to November, a salinity front of a quasi-latitudinal location is observed. The greatest desalination, associated with the spread of river flow across the sea, is observed in June. The formation of the salinity field in the Northern Caspian Sea is greatly influenced by the wind field. In the middle and southern parts of the sea, salinity fluctuations are small. Basically it is 11.2-12.8 units. psu, increasing in the southern and eastern directions. With depth, salinity increases slightly (by 0.1-0.2 units psu).
In the deep-sea part of the Caspian Sea, in the vertical profile of salinity, characteristic deflections of isohalines and local extrema are observed in the area of the eastern continental slope, which indicate processes of bottom sliding of waters salinizing in the eastern shallow waters of the South Caspian. The magnitude of salinity also strongly depends on sea level and (which is interconnected) on the volume of continental runoff.
Bottom relief
The relief of the northern part of the Caspian Sea is a shallow undulating plain with banks and accumulative islands, the average depth of the Northern Caspian Sea is about 4-8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle Caspian. The Middle Caspian is quite deep, the water depth in the Derbent depression reaches 788 meters. The Absheron threshold separates the Middle and Southern Caspian Seas. The Southern Caspian is considered deep-sea; the water depth in the South Caspian depression reaches 1025 meters from the surface of the Caspian Sea. Shell sands are widespread on the Caspian shelf, deep-sea 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 and subtropical in the southern part. In winter average monthly temperature The Caspian Sea 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 was 44 degrees.
The average annual precipitation is 200 millimeters per year, ranging from 90-100 millimeters in the arid eastern part to 1,700 millimeters along 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 Sea 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, the wind rose is dominated by north winds. In the autumn and winter months, winds become stronger, with wind speeds often reaching 35-40 meters per second. The most windy areas are the Absheron Peninsula and the environs of Makhachkala - Derbent, where the highest wave was recorded - 11 meters.
Currents
Water circulation in the Caspian Sea is related to runoff and winds. Since most of the drainage occurs in the Northern Caspian Sea, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current divides 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 Sea is represented by 1809 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian world, where most of the world's sturgeon reserves are concentrated, as well as freshwater fish such as roach, carp, and pike perch. The Caspian Sea is the habitat of fish such as carp, mullet, sprat, kutum, bream, salmon, perch, and pike. The Caspian Sea is also home to a marine mammal, the 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. Among the plants in the Caspian Sea, the predominant algae are blue-green, diatoms, red, brown, characeae and others, and among the flowering plants - zoster and ruppia. In origin, the flora is predominantly of Neogene age, but some plants were brought into the Caspian Sea by humans deliberately or on the bottoms of ships.
Origin of the Caspian Sea
The Caspian Sea is of oceanic origin - its bed is folded earth's crust oceanic type. It was formed approximately 10 million years ago, when the closed Sarmatian Sea, which lost contact with the world's oceans approximately 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 u cave south coast The Caspian Sea indicates that man lived in these areas approximately 75 thousand years ago. The first mentions of the Caspian Sea and the tribes living on its coast are found in Herodotus. Around the V-II centuries. BC e. Saka tribes lived on the Caspian coast. Later, during the period of 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, Russians sailed the Caspian Sea from the 9th - 10th centuries.
Research of the Caspian Sea
Research of the Caspian Sea was started by Peter the Great, when, on his order, an expedition was organized in 1714-1715 under the leadership of A. Bekovich-Cherkassky. In the 1820s, hydrographic research was 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 surveys of the shores were carried out by I. F. Kolodkin, in the mid-19th century. - instrumental geographical survey under the direction of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary research on the hydrology and hydrobiology of the Caspian Sea was carried out under the leadership of N. M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power, geological research by I.M. Gubkin and other Soviet geologists was actively carried out in the Caspian Sea, mainly aimed at searching for oil, as well as research into the study of water balance and level fluctuations in the Caspian Sea.
Mining of oil and gas
Many oil and gas fields are being developed in the Caspian Sea. Proven oil resources in the Caspian Sea are about 10 billion tons, total oil and gas condensate resources 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 in 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. There are ferry crossings on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with Sea of Azov through the Volga, Don and Volga-Don Canal rivers.
Fishing and seafood production
Fishing (sturgeon, bream, carp, pike perch, sprat), caviar production, as well as seal fishing. More than 90 percent of the world's sturgeon catch occurs in the Caspian Sea. In addition to industrial mining, illegal fishing of sturgeon and their caviar flourishes in the Caspian Sea.
Recreational resources
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, according to the degree of development of resorts and tourism industry Caspian coast loses noticeably Black Sea coast Caucasus. At the same time, in last years The tourism industry is actively developing on the coasts of Azerbaijan, Iran, Turkmenistan and Russian Dagestan.
Ecological problems
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 life of coastal cities, as well as the flooding of individual objects due to rising levels of the Caspian Sea. Predatory production of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeon and to 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 unresolved disagreements related to the division of Caspian shelf resources - oil and gas, as well as biological resources. For a long time, negotiations were ongoing 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 insisted on dividing the Caspian by one-fifth between all 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
, Kura
42° N. w. 51° east d. HGIOLCaspian Sea- the largest closed body of water on Earth, which can be classified as the largest closed lake, or as a full-fledged sea, due to its size, and also because its bed is composed of oceanic-type crust. Located at the junction of Europe and Asia. The water in the Caspian Sea is brackish, 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 area of the Caspian Sea is currently approximately 371,000 km², the maximum depth is 1025 m.
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Subtitles
Etymology
Geographical position
The Caspian Sea is located at the junction of Europe and Asia. The length of the 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° in .d.).
According to physical and geographical conditions, the Caspian Sea is conventionally divided into three parts - the Northern Caspian (25% of the sea area), the Middle Caspian (36%) and the Southern Caspian (39%). The conditional border between the Northern and Middle Caspian runs along the line Chechen Island - Cape Tyub-Karagan, between the Middle and Southern Caspian - along the line Chilov Island - Cape Gan-Gulu.
Coast
The territory adjacent to the Caspian Sea is called the Caspian region.
Peninsulas
- Absheron Peninsula, located on the western coast of the Caspian Sea on the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory the cities of Baku and Sumgait are located
- Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory is the city of Aktau
Islands
There are about 50 large and medium-sized islands in the Caspian Sea with a total area of approximately 350 square kilometers.
Largest islands:
Bays
Large bays:
Kara-Bogaz-Gol
Off the east coast is salt Lake Kara-Bogaz-Gol, until 1980, was a bay-lagoon of the Caspian Sea, connected to it by a narrow strait. In 1980, a dam was built separating Kara-Bogaz-Gol from the Caspian Sea, and in 1984 a culvert was built, after which the level of Kara-Bogaz-Gol dropped by several meters. In 1992, the strait was restored, through which water flows from the Caspian Sea to Kara-Bogaz-Gol and evaporates there. Every year, 8-10 cubic kilometers of water (according to other sources - 25 cubic kilometers) and about 15 million tons of salt flow into Kara-Bogaz-Gol from the Caspian Sea.
Rivers flowing into the Caspian Sea
130 rivers flow into the Caspian Sea, of which 9 rivers have a delta-shaped mouth. Large rivers flowing into the Caspian Sea are Volga, Terek, Sulak, Samur (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Atrek (Turkmenistan), Sefidrud (Iran). The largest river flowing into the Caspian Sea is the Volga, its average annual flow is 215-224 cubic kilometers. The Volga, Ural, Terek, Sulak and Emba provide up to 88-90% of the annual flow into the Caspian Sea.
Basin of the Caspian Sea
Coastal states
According to the Intergovernmental Economic Conference of the Caspian States:
The Caspian Sea washes the shores of five coastal states:
Cities on the Caspian Sea coast
On the Russian coast are the cities of Lagan, Makhachkala, Kaspiysk, Izberbash, Dagestanskie Ogni 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. The predominant plants in the Caspian Sea are algae - blue-green, diatoms, red, brown, characeae and others, and flowering plants - zoster and ruppia. In origin, the flora is predominantly of Neogene age, however, some plants were brought into the Caspian Sea by humans deliberately, or on the bottoms of ships.
Story
Origin
The Caspian Sea is of oceanic origin - its bed is composed of oceanic-type crust. 13 million l. n. the resulting Alps separated the Sarmatian Sea from the Mediterranean. 3.4 - 1.8 million l. n. (Pliocene) there was the Akchagyl Sea, the sediments of which were studied by N. I. Andrusov. It was originally formed on the site of the dried-up Pontic Sea, from which Lake Balakhanskoe (in the southern Caspian Sea) remained. The Akchagyl transgression gave way to the Domashkin regression (a drop of 20 - 40 m from the level of the Akchagyl basin), accompanied by a strong desalination of sea waters, which is due to the cessation of the flow of sea (ocean) waters from the outside. After a short Domashkin regression at the beginning of the Quaternary period (Eopleistocene), the Caspian Sea is almost restored in the form of the Absheron Sea, which covers the Caspian Sea and floods the territories of Turkmenistan and the Lower Volga region. At the beginning of the Absheron transgression, the basin turns into a brackish water body. The Absheron Sea exists from 1.7 to 1 million years ago. The beginning of the Pleistocene in the Caspian Sea was marked by a long and deep Turkic regression (-150 m to −200 m), corresponding to the Matuyama-Brunhes magnetic reversal (0.8 million years ago). The water mass of the Turkyan basin with an area of 208 thousand km² was concentrated in the South Caspian and part of the Middle Caspian basins, between which there was a shallow strait in the area of the Absheron threshold. In the early Neopleistocene, after the Turkic regression, there existed an isolated Early Baku and a Late Baku (level up to 20 m) drainage basins (about 400 thousand years ago). The Vened (Mishovdag) regression divided the Baku and Urundzhik (middle Neopleistocene, up to −15 m) transgressions at the end of the early - beginning of the late Pleistocene (basin area - 336 thousand km²). Between the marine Urundzhik and Khazar deposits, a large deep Cheleken regression (up to −20 m) was noted, corresponding to the optimum of the Likhvin interglacial (350-300 thousand years ago). In the Middle Neopleistocene there were basins: early Khazar (200 thousand years ago), early Khazar middle (level up to 35-40 m) and early Khazar late. In the late Neopleistocene, there was an isolated late Khazar basin (level up to −10 m, 100 thousand years ago), after which a small Chernoyarsk regression occurred in the second half - the end of the Middle Pleistocene (thermoluminescent dates 122-184 thousand years ago), in in turn, replaced by the Hyrcanian (Gyurgyan) basin.
The deep long-term Atelian regression of the mid-Late Pleistocene at the initial stage had a level of −20 - −25 m, at the maximum stage −100 - −120 m, at the third stage - −45 - −50 m. At the maximum, the basin area is reduced to 228 thousand km² . After Atel regression (−120 - −140 m), approx. 17 thousand l. n. The early Khvalynian transgression began - up to + 50 m (the Manych-Kerch Strait was functioning), which was interrupted by the Eltonian regression. The Early Khvalyn II basin (level up to 50 m) was replaced at the beginning of the Holocene by a short-term Enotaev regression (from −45 to −110 m), coinciding in time with the end of the Preboreal and the beginning of the Boreal. The Enotayevskaya regression gave way to the Late Khvalynskaya transgression (0 m). The Late Khvalynian transgression was replaced in the Holocene (ca. 9-7 thousand years ago or 7.2-6.4 thousand years ago) by the Mangyshlak regression (from −50 to −90 m). The Mangyshlak regression gave way during the first phase of interglacial cooling and humidification (Atlantic period) to the New Caspian transgression. The New Caspian basin was brackish-water (11-13 ‰), warm-water and isolated (level up to −19 m). At least three cycles of transgressive-regressive phases have been recorded in the development of the Novo-Caspian basin. The Dagestan (Gousan) transgression previously belonged to the initial stage of the New Caspian era, but the absence of a leading New Caspian form in its sediments Cerastoderma glaucum (Cardium edule) gives grounds for identifying it as an independent transgression of the Caspian Sea. The Izberbash regression, separating the Dagestan and the Neo-Caspian transgressions of the Caspian Sea itself, occurred between 4.3 and 3.9 thousand years ago. Judging by the structure of the Turali section (Dagestan) and radiocarbon analysis data, transgressions were noted twice - about 1900 and 1700 years ago.
Anthropological and cultural history of the Caspian Sea
Shipping
Shipping is developed in the Caspian Sea. There are ferry crossings on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with the Sea of Azov through the Volga, Don and Volga-Don Canal rivers.
Fishing and seafood production
Fishing (sturgeon, bream, carp, pike perch, sprat), caviar production, as well as seal fishing. More than 90 percent of the world's sturgeon catch occurs in the Caspian Sea. In addition to industrial mining, illegal mining of sturgeon and their caviar flourishes in the Caspian Sea.
Recreational resources
Natural environment of the Caspian coast with sandy beaches, mineral waters and healing mud in the coastal zone creates good conditions for relaxation and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast is noticeably inferior to the Black Sea coast of the Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coasts of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. Azerbaijan is actively developing resort area in the Baku region. A world-class resort has now been created in Amburan, another modern tourist complex is being built in the area of the village of Nardaran, holidays in the sanatoriums of the villages of Bilgah and Zagulba are very popular. A resort area is also being developed in Nabran, in northern Azerbaijan. However high prices, in general, the low level of service and lack of advertising lead to the fact that Caspian resorts almost no foreign tourists. The development of the tourism industry in Turkmenistan is hampered by a long-term policy of isolation; in Iran, Sharia law, due to which mass recreation foreign tourists on the Caspian coast of Iran is impossible.
Ecological problems
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 life activity of coastal cities, as well as the flooding of individual objects due to rising levels of the Caspian Sea. Predatory production of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeon and to forced restrictions on their production and export.
Legal status
After the collapse of the USSR, the division of the Caspian Sea has long been and still remains the subject of unresolved disagreements related to the division of Caspian shelf resources - oil and gas, as well as biological resources. For a long time, negotiations were ongoing 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 insisted on dividing the Caspian by one-fifth between all Caspian states.
In relation to the Caspian Sea, the key is the physical-geographical circumstance that it is a closed inland body of water 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 1982 UN Convention on the Law of the Sea, should not automatically apply to the Caspian Sea. Based on this, in relation to the Caspian Sea 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 vessels flying the flag of non-Caspian states sailing in its waters.
Negotiations on the legal status of the Caspian Sea are currently ongoing.
Delineation of sections of the Caspian seabed for subsoil use
The Russian Federation concluded an agreement with Kazakhstan on delimiting 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 thereto dated May 13, 2002), an agreement with Azerbaijan on delimiting adjacent areas of the bottom of the northern part of the Caspian Sea (dated September 23, 2002), as well as the trilateral Russian-Azerbaijani-Kazakh agreement on the junction point of the demarcation lines of adjacent sections of the Caspian Sea bottom (dated May 14, 2003), which established geographical coordinates dividing lines limiting the areas of the seabed within which the parties exercise their sovereign rights in the field of exploration and production of mineral resources.