Caspian Sea. Where is it located, photos, characteristics, area, holiday resorts. The largest lake in the world is the Caspian Sea. On what continent is the Caspian Sea located?

The Caspian Sea is called the most big lake on our planet. It is located between Europe and Asia and is called the sea for its size.

Caspian Sea

The water level is 28m below the level. The water in the Caspian Sea has lower salinity in the north in the delta. The highest salinity is observed in the southern regions.

The Caspian Sea covers an area of 371 thousand km2, the greatest depth is 1025 meters (South Caspian Depression). The coastline is estimated to be from 6,500 to 6,700 km, and if we take it together with the islands, then more than 7,000 km.

The seashore is mostly low-lying and smooth. If you look at the northern part, there are many islands and water channels cut by the Volga and the Urals. In these places the shore is swampy and covered with thickets. From the east, a semi-desert and desert area with limestone shores approaches the sea. The region of the Kazakh Gulf, the Absheron Peninsula and the Kara-Bogaz-Gol Bay have winding shores.

Bottom relief

The bottom topography is divided into three main forms. Shelf in the northern part, average depth here from 4 to 9 m, the maximum is 24 m, which gradually increases and reaches 100 m. The continental slope in the middle part drops to 500 m. The northern part is separated from the middle by the Mangyshlak threshold. Here one of the deepest places is the Derbent depression (788 m).

2. Heraz, Babol, Sefudrud, Gorgan, Polerud, Chalus, Tejen - https://site/russia/travel/po-dagestanu.html;

4. Atrek - Turkmenistan;

Samur is located on the border between Azerbaijan and Russia, Astarachay is on the border of Azerbaijan and Iran.

The Caspian Sea belongs to five states. From the west and north-west, the length of the coast of 695 km is the territory of Russia. Most of the 2,320 km coastline belongs to Kazakhstan in the east and northeast. Turkmenistan has 1200 km in the south-eastern part, Iran has 724 km in the south and Azerbaijan has 955 km of coastline in the south-west.

In addition to the five states that have access to the sea, the Caspian basin also includes Armenia, Turkey, and Georgia. The sea is connected to the World Ocean by the Volga (Volga-Baltic Route, White Sea-Baltic Canal). There is a connection with the Azov and Black Seas through the Volga-Don Canal, and with the Moscow River (Moscow Canal).

The main ports are Baku in Azerbaijan; Makhachkala in; Aktau in Kazakhstan; Olya in Russia; Noushehr, Bandar-Torkemen and Anzali in Iran.

The largest bays of the Caspian Sea: Agrakhansky, Kizlyarsky, Kaydak, Kazakhsky, Dead Kultuk, Mangyshlaksky, Hasan-kuli, Turkmenbashi, Kazakhsky, Gyzlar, Anzeli, Astrakhan, Gyzlar.

Until 1980, Kara-Bogaz-Gol was a bay-lagoon, which was connected to the sea by a narrow strait. Now it is a salt lake, separated from the sea by a dam. After the construction of the dam, the water began to decrease sharply, so a culvert had to be built. Through it, up to 25 km3 of water enters the lake annually.

Water temperature

The greatest temperature fluctuations are observed in winter. In shallow water it reaches 100 in winter. The difference between summer and winter temperatures reaches 240. On the coast in winter it is always 2 degrees lower than in the open sea. Optimal heating of the water occurs in July-August; in shallow water the temperature reaches 320. But at this time, northwest winds raise cold layers of water (upwelling). This process begins already in June and reaches intensity in August. The temperature at the surface of the water decreases. The temperature difference between the layers disappears by November.

The climate in the northern part of the sea is continental, in the middle part it is temperate, and in the southern part it is subtropical. Temperatures are always higher on the east coast than on the west coast. One day, 44 degrees was recorded on the east coast.

Composition of Caspian waters

About salinity is 0.3%. This is a typical desalinated pool. But the further south you go, the higher the salinity. In the southern part of the sea it already reaches 13%, and in Kara-Bogaz-Gol it is more than 300%.

Storms are frequent in shallow areas. They arise due to changes in atmospheric pressure. Waves can reach 4 meters.

The water balance of the sea depends on river flows and precipitation. Among them, the Volga makes up almost 80% of all other rivers.

In recent years, there has been rapid water pollution with petroleum products and phenols. Their level already exceeds the permissible level.

Minerals

Hydrocarbon production began back in the 19th century. These are the main ones Natural resources. There are also mineral and balneological biological resources here. Nowadays, in addition to gas and oil production, marine salts (astrakhanite, mirabalite, halite), sand, limestone, and clay are mined on the shelf.

Animal and plant life

The fauna of the Caspian Sea includes up to 1800 species. Of these, 415 are vertebrates, 101 are fish species, and there is a world stock of sturgeon. Freshwater fish such as carp, pike perch, and roach also live here. They catch carp, salmon, pike, and bream in the sea. The Caspian Sea is the habitat of one of the mammals - the seal.

Plants include blue-green, brown, and red algae. Zostera and ruppia also grow; they are classified as flowering algae.

Plankton brought into the sea by birds begins to bloom in the spring, the sea is literally covered with greenery, and during flowering the rhizosolinium paints most of the sea area yellow-green. Clusters of rhizosolenia are so thick that they can even calm waves. In some places near the coast, literally meadows of algae have grown.

On the coast you can see both local and migratory birds. In the south, geese and ducks winter, and birds such as pelicans, herons, and flamingos arrange nesting grounds.

The Caspian Sea contains almost 90% of the world's sturgeon stocks. But recently the environment has been deteriorating; you can often meet poachers who hunt sturgeon for their expensive caviar.

States are investing a lot of money to improve the situation. They are purifying wastewater and building fish breeding factories; despite these measures, sturgeon production has to be limited.

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

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

Why is the Caspian considered neither a lake nor a sea?

To be considered a sea, the Caspian Sea must have access to the ocean; this is one of the most important conditions for which a body of water can be called a sea. But the Caspian Sea has no access to the ocean, so it is considered a closed body of water not connected to the World Ocean.

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

Due to its specific geographical and hydrological characteristics, the reservoir received a special legal status. The summit participants decided that the Caspian Sea is an inland body of water that does not have a direct connection with the World Ocean, and therefore cannot be considered a sea, and at the same time, due to its size, water composition and bottom features, cannot be considered a lake.

What has been achieved since the signing of the Convention?

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

“The most important thing that was achieved was to fix that the Caspian Sea will be demilitarized for all Caspian states. There will be no other military personnel there except those representing the countries that signed the Caspian Agreement. This is fundamental and main question, which was important to record. Everything else, what is divided proportionally into zones of influence, zones of extraction of biological resources, zones of extraction of shelf resources, was not so important. As we remember, in the last twenty years the military has been actively seeking to enter the region. The USA even wanted to build their own there military base", says Martynov.

In addition to the distribution of each country's shares in the oil and gas fields of the Caspian basin, the Convention also provides for the construction of pipelines. As stated in the document, the rules for laying them provide for the consent of only neighboring countries, and not all countries of the Caspian Sea. After signing the agreement, Turkmenistan, in particular, stated that it was ready to lay pipelines along the bottom of the Caspian Sea, which would allow it to export its gas through Azerbaijan to Europe. The consent of Russia, which previously insisted that the project could only be implemented with the permission of all five Caspian states, is now no longer required. They plan to subsequently connect the gas pipeline to the Trans-Anatolian gas pipeline, through which natural gas will flow through the territory of Azerbaijan, Georgia and Turkey to Greece.

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

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

V. N. MIKHAILOV

The Caspian Sea is the largest closed lake on the planet. This body of water is called the sea for its huge size, brackish water and a regime similar to the sea. The level of the Caspian Sea-lake lies much lower than the level of the World Ocean. At the beginning of 2000, it was around -27 abs. m. At this level, the area of the Caspian Sea is ~ 393 thousand km2 and the volume of water is 78,600 km3. The average and maximum depths are 208 and 1025 m, respectively.

The Caspian Sea stretches from south to north (Fig. 1). The Caspian Sea washes the shores of Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran. The reservoir is rich in fish, its bottom and shores are rich in oil and gas. The Caspian Sea has been studied quite well, but many mysteries remain in its regime. The most characteristic feature of a reservoir is the instability of the level with sharp drops and rises. The last increase in the level of the Caspian Sea occurred before our eyes from 1978 to 1995. It gave rise to many rumors and speculation. Numerous publications appeared in the press talking about catastrophic floods and an environmental disaster. They often wrote that the rise in the level of the Caspian Sea led to the flooding of almost the entire Volga delta. What is true in the statements made? What is the reason for this behavior of the Caspian Sea?

WHAT HAPPENED TO THE CASPIAN IN THE XX CENTURY

Systematic observations of the level of the Caspian Sea began in 1837. In the second half of the 19th century, the average annual values of the Caspian Sea level were in the range from – 26 to – 25.5 abs. m and had a slight downward trend. This trend continued into the 20th century (Fig. 2). In the period from 1929 to 1941, sea level dropped sharply (by almost 2 m - from - 25.88 to - 27.84 abs. m). In subsequent years, the level continued to fall and, having decreased by approximately 1.2 m, reached in 1977 the lowest level during the observation period - 29.01 abs. m. Then the sea level began to rise rapidly and, having risen by 2.35 m by 1995, reached 26.66 abs. m. In the next four years, the average sea level dropped by almost 30 cm. Its average levels were - 26.80 in 1996, - 26.95 in 1997, - 26.94 in 1998 and - 27.00 abs. m in 1999.

The decrease in sea level in 1930-1970 led to the shallowing of coastal waters, the extension of the coastline towards the sea, and the formation of wide beaches. The latter was perhaps the only positive consequence of the drop in level. There were significantly more negative consequences. As the level dropped, the areas of feeding grounds for fish stocks in the northern Caspian Sea decreased. The shallow-water estuarine coastal area of the Volga began to quickly become overgrown with aquatic vegetation, which worsened the conditions for the passage of fish to spawn in the Volga. Fish catches have sharply decreased, especially valuable species: sturgeon and sterlet. Shipping began to suffer due to the fact that the depths in the approach channels decreased, especially near the Volga delta.

The rise in levels from 1978 to 1995 was not only unexpected, but also led to even greater negative consequences. After all, both the economy and the population of coastal areas have already adapted to the low level.

Many sectors of the economy began to suffer damage. Significant territories were in the zone of flooding and inundation, especially in the northern (plain) part of Dagestan, in Kalmykia and Astrakhan region. The cities of Derbent, Kaspiysk, Makhachkala, Sulak, Kaspiysky (Lagan) and dozens of other smaller settlements suffered from the rise in level. Significant areas of agricultural land have been flooded and submerged. Roads and power lines, engineering structures of industrial enterprises and public utilities are being destroyed. A threatening situation has developed with fish farming enterprises. Abrasion processes in the coastal zone and the influence of seawater surges have intensified. In recent years, the flora and fauna of the seaside and coastal zone of the Volga delta have suffered significant damage.

Due to the increase in depth in the shallow waters of the Northern Caspian and the reduction in the areas occupied by aquatic vegetation in these places, the conditions for the reproduction of stocks of anadromous and semi-anadromous fish and the conditions for their migration to the delta for spawning have somewhat improved. However, the predominance of negative consequences from rising sea levels has led to talk of an environmental catastrophe. The development of measures to protect national economic facilities and settlements from the advancing sea began.

HOW UNUSUAL IS THE CURRENT BEHAVIOR OF THE CASPIAN SEA?

Research into the life history of the Caspian Sea can help answer this question. Of course, there are no direct observations of the past regime of the Caspian Sea, but there is archaeological, cartographic and other evidence for historical time and the results of paleogeographic studies covering a longer period.

It has been proven that during the Pleistocene (the last 700-500 thousand years), the level of the Caspian Sea underwent large-scale fluctuations in the range of about 200 m: from -140 to + 50 abs. m. During this period of time, four stages are distinguished in the history of the Caspian Sea: Baku, Khazar, Khvalyn and Novo-Caspian (Fig. 3). Each stage included several transgressions and regressions. The Baku transgression occurred 400-500 thousand years ago, sea level rose to 5 abs. m. During the Khazar stage, there were two transgressions: early Khazar (250-300 thousand years ago, maximum level 10 abs. m) and late Khazar (100-200 thousand years ago, highest level -15 abs. m). The Khvalynian stage in the history of the Caspian Sea included two transgressions: the largest during the Pleistocene period, the Early Khvalynian (40-70 thousand years ago, maximum level 47 absolute meters, which is 74 m higher than the modern one) and the Late Khvalynian (10-20 thousand years ago, rise level up to 0 absolute m). These transgressions were separated by the deep Enotayev regression (22-17 thousand years ago), when sea level dropped to -64 abs. m and was 37 m lower than the modern one.

Rice. 4. Fluctuations in the level of the Caspian Sea over the past 10 thousand years. P is the natural range of fluctuations in the level of the Caspian Sea under climatic conditions characteristic of the sub-Atlantic Holocene era (risk zone). I-IV - stages of the New Caspian transgression; M - Mangyshlak, D - Derbent regression

Significant fluctuations in the level of the Caspian Sea also occurred during the New Caspian stage of its history, which coincided with the Holocene (the last 10 thousand years). After the Mangyshlak regression (10 thousand years ago, the level dropped to – 50 abs. m), five stages of the New Caspian transgression were noted, separated by small regressions (Fig. 4). Following fluctuations in sea level—its transgressions and regressions—the outline of the reservoir also changed (Fig. 5).

Over historical time (2000 years), the range of change in the average level of the Caspian Sea was 7 m – from – 32 to – 25 abs. m (see Fig. 4). The minimum level in the last 2000 years was during the Derbent regression (VI-VII centuries AD), when it decreased to – 32 abs. m. During the time elapsed after the Derbent regression, the average sea level changed in an even narrower range - from – 30 to – 25 abs. m. This range of level changes is called the risk zone.

Thus, the level of the Caspian Sea has experienced fluctuations before, and in the past they were more significant than in the 20th century. Such periodic fluctuations are a normal manifestation of the unstable state of a closed reservoir with variable conditions at the outer boundaries. Therefore, there is nothing unusual in the decrease and increase in the level of the Caspian Sea.

Fluctuations in the level of the Caspian Sea in the past, apparently, did not lead to irreversible degradation of its biota. Of course, sharp drops in sea level created temporary unfavorable conditions, for example for fish stocks. However, as the level rose, the situation corrected itself. Natural conditions coastal zone (vegetation, bottom animals, fish) experience periodic changes along with sea level fluctuations and, apparently, have a certain margin of stability and resistance to external influences. After all, the most valuable sturgeon stock has always been in the Caspian basin, regardless of sea level fluctuations, quickly overcoming temporary deterioration in living conditions.

Rumors that rising sea levels caused floods throughout the Volga delta were not confirmed. Moreover, it turned out that the increase in water levels even in the lower part of the delta is inadequate to the magnitude of the sea level rise. The increase in water level in the lower part of the delta during the low-water period did not exceed 0.2-0.3 m, and during the flood it almost did not appear at all. At the maximum level of the Caspian Sea in 1995, the backwater from the sea extended along the deepest branch of the delta, Bakhtemiru, no more than 90 km, and along other branches no more than 30 km. Therefore, only the islands on the seashore and the narrow coastal strip of the delta were flooded. Flooding in the upper and middle parts of the delta was associated with high floods in 1991 and 1995 (which is a normal phenomenon for the Volga delta) and with the unsatisfactory condition of protective dams. The reason for the weak influence of sea level rise on the regime of the Volga delta is the presence of a huge shallow coastal zone, which dampens the impact of the sea on the delta.

As for the negative impact of sea level rise on the economy and life of the population in the coastal zone, the following should be recalled. At the end of the last century, sea levels were higher than they are now, and this was in no way perceived as an environmental disaster. And before the level was even higher. Meanwhile, Astrakhan has been known since the middle of the 13th century, and here in the 13th - mid-16th centuries the capital of the Golden Horde, Sarai-Batu, was located. These and many others settlements on the Caspian coast did not suffer from high levels, since they were located on elevated places and during abnormal flood levels or surges, people temporarily moved from low places to higher places.

Why is it that now the consequences of sea level rise, even to lower levels, are perceived as a catastrophe? The reason for the enormous damage suffered by the national economy is not the rise in level, but the thoughtless and short-sighted development of a strip of land within the mentioned risk zone, freed (as it turned out, temporarily!) from under sea level after 1929, that is, when the level decreased below the mark - 26 abs. m. The buildings erected in the risk zone, naturally, turned out to be flooded and partially destroyed. Now, when a territory developed and polluted by humans is flooded, a dangerous ecological situation is actually created, the source of which is not natural processes, but unreasonable economic activity.

ABOUT THE REASONS FOR CASPIAN LEVEL FLUCTUATIONS

When considering the reasons for fluctuations in the level of the Caspian Sea, it is necessary to pay attention to the confrontation between two concepts in this area: geological and climatic. Significant contradictions in these approaches emerged, for example, at the international conference "Caspian-95".

According to the geological concept, the causes of changes in the level of the Caspian Sea include processes of two groups. The processes of the first group, according to geologists, lead to a change in volume Caspian basin and, as a consequence, to changes in sea level. Such processes include vertical and horizontal tectonic movements of the earth's crust, accumulation of bottom sediments and seismic phenomena. The second group includes processes that, as geologists believe, affect the underground flow into the sea, either increasing or decreasing it. Such processes are called periodic extrusion or absorption of waters that saturate bottom sediments under the influence of changing tectonic stresses (changes in periods of compression and extension), as well as technogenic destabilization of the subsurface caused by oil and gas production or underground nuclear explosions. It is impossible to deny the fundamental possibility of the influence of geological processes on the morphology and morphometry of the Caspian basin and underground flow. However, at present, the quantitative connection of geological factors with fluctuations in the level of the Caspian Sea has not been proven.

There is no doubt that tectonic movements played a decisive role in the initial stages of the formation of the Caspian basin. However, if we take into account that the Caspian Sea basin is located within a geologically heterogeneous territory, which results in a periodic rather than linear nature of tectonic movements with repeated changes in sign, then one should hardly expect a noticeable change in the capacity of the basin. The tectonic hypothesis is also not supported by the fact that coastlines New Caspian transgressions on all sections of the Caspian coast (with the exception of certain areas within the Absheron archipelago) are at the same level.

There is no reason to believe that the cause of fluctuations in the level of the Caspian Sea is a change in the capacity of its depression due to the accumulation of sediments. The rate of filling of the basin with bottom sediments, among which the main role is played by river discharges, is estimated, according to modern data, to be about 1 mm/year or less, which is two orders of magnitude less than the currently observed changes in sea level. Seismic deformations, which are noted only near the epicenter and attenuate at close distances from it, cannot have any significant effect on the volume of the Caspian basin.

As for the periodic large-scale discharge of groundwater into the Caspian Sea, its mechanism is still unclear. At the same time, this hypothesis is contradicted, according to E.G. Maevu, firstly, the undisturbed stratification of silt waters, indicating the absence of noticeable migrations of water through the thickness of bottom sediments, and secondly, the absence of proven powerful hydrological, hydrochemical and sedimentation anomalies in the sea, which should have accompanied large-scale discharge of groundwater that could influence changes in reservoir level.

The main proof of the insignificant role of geological factors at present is the convincing quantitative confirmation of the plausibility of the second, climatic, or more precisely, water-balance concept of Caspian level fluctuations.

CHANGES IN THE COMPONENTS OF THE CASPIAN WATER BALANCE AS THE MAIN REASON FOR FLUCTUATIONS IN ITS LEVEL

For the first time, fluctuations in the level of the Caspian Sea were explained by changes climatic conditions(more specifically river flow, evaporation and precipitation on the sea surface) also E.Kh. Lentz (1836) and A.I. Voeikov (1884). Later, the leading role of changes in the components of the water balance in sea level fluctuations was proven again and again by hydrologists, oceanologists, physical geographers and geomorphologists.

The key to most of the studies mentioned is the development of a water balance equation and the analysis of its components. The meaning of this equation is as follows: the change in the volume of water in the sea is the difference between the incoming (river and underground runoff, precipitation on the sea surface) and outgoing (evaporation from the sea surface and outflow of water into the Kara-Bogaz-Gol Bay) components of the water balance. The change in the level of the Caspian Sea is the quotient of the change in the volume of its waters divided by the area of the sea. The analysis showed that the leading role in the water balance of the sea belongs to the ratio of the runoff of the Volga, Ural, Terek, Sulak, Samur, Kura rivers and visible or effective evaporation, the difference between evaporation and precipitation on the sea surface. Analysis of the components of the water balance revealed that the largest contribution (up to 72% of the variance) to the level variability is made by the influx of river water, and more specifically, the zone of runoff formation in the Volga basin. As for the reasons for the change in the Volga runoff itself, many researchers believe that they are associated with the variability of atmospheric precipitation (mainly winter) in the river basin. And the precipitation regime, in turn, is determined by atmospheric circulation. It has long been proven that the latitudinal type of atmospheric circulation contributes to an increase in precipitation in the Volga basin, and the meridional type contributes to a decrease.

V.N. Malinin revealed that the root cause of moisture entering the Volga basin should be sought in the North Atlantic, and specifically in the Norwegian Sea. It is there that an increase in evaporation from the sea surface leads to an increase in the amount of moisture transferred to the continent and, accordingly, to an increase in atmospheric precipitation in the Volga basin. The latest data on the water balance of the Caspian Sea, obtained by employees of the State Oceanographic Institute R.E. Nikonova and V.N. Bortnik, are given with clarifications by the author in table. 1. These data provide convincing evidence that the main causes of both the rapid drop in sea level in the 1930s and the sharp rise in 1978-1995 were changes in river flow, as well as visible evaporation.

Bearing in mind that river flow is one of the main factors influencing the water balance and, as a consequence, the level of the Caspian Sea (and the Volga flow provides at least 80% of the total river flow into the sea and about 70% of the incoming part of the Caspian water balance), It would be interesting to find a connection between sea level and the flow of the Volga alone, measured most accurately. Direct correlation of these quantities does not give satisfactory results.

However, the connection between sea level and Volga runoff is clearly visible if we take into account the river flow not for every year, but take the ordinates of the difference integral runoff curve, that is, the sequential sum of normalized deviations of annual runoff values from the long-term average value (norm). Even a visual comparison of the course of the average annual levels of the Caspian Sea and the difference integral curve of the Volga runoff (see Fig. 2) allows us to identify their similarities.

Over the entire 98-year period of observations of the Volga runoff (the village of Verkhnee Lebyazhye at the top of the delta) and sea level (Makhachkala), the correlation coefficient between the sea level and the ordinates of the difference integral runoff curve was 0.73. If we discard years with small changes in level (1900-1928), then the correlation coefficient increases to 0.85. If we take for analysis a period with a rapid decline (1929-1941) and a rise in level (1978-1995), then the overall correlation coefficient will be 0.987, and separately for both periods 0.990 and 0.979, respectively.

The above calculation results fully confirm the conclusion that during periods of a sharp decrease or rise in sea level, the levels themselves are closely related to the runoff (more precisely, to the sum of its annual deviations from the norm).

A special task is to assess the role of anthropogenic factors in fluctuations in the level of the Caspian Sea, and first of all, the reduction of river flow due to irreversible losses due to the filling of reservoirs, evaporation from the surface of artificial reservoirs, and water intake for irrigation. It is believed that since the 40s, irreversible water consumption has steadily increased, which has led to a reduction in the influx of river water to the Caspian Sea and an additional decrease in its level compared to the natural one. According to V.N. Malinin, by the end of the 80s, the difference between the actual sea level and the restored (natural) reached almost 1.5 m. At the same time, the total irrecoverable water consumption in the Caspian basin was estimated in those years at 36-45 km3/year (of which the Volga accounted for about 26 km3/year). If it were not for the withdrawal of river flow, sea level rise would have begun not in the late 70s, but in the late 50s.

The increase in water consumption in the Caspian basin by 2000 was predicted first to 65 km3/year, and then to 55 km3/year (36 of which were accounted for by the Volga). Such an increase in irrevocable losses of river flow should have reduced the level of the Caspian Sea by more than 0.5 m by 2000. In connection with assessing the impact of irreversible water consumption on the level of the Caspian Sea, we note the following. Firstly, estimates in the literature of the volumes of water intake and losses due to evaporation from the surface of reservoirs in the Volga basin are apparently significantly overestimated. Secondly, forecasts for the growth of water consumption turned out to be erroneous. The forecasts included the pace of development of water-consuming sectors of the economy (especially irrigation), which not only turned out to be unrealistic, but also gave way to a decline in production in recent years. In fact, as A.E. points out. Asarin (1997), by 1990, water consumption in the Caspian basin was about 40 km3/year, and has now decreased to 30-35 km3/year (in the Volga basin up to 24 km3/year). Therefore, the “anthropogenic” difference between the natural and actual sea level is currently not as great as predicted.

ABOUT POSSIBLE FLUCTUATIONS IN THE CASPIAN SEA LEVEL IN THE FUTURE

The author does not set himself the goal of analyzing in detail the numerous forecasts of fluctuations in the level of the Caspian Sea (this is an independent and difficult task). The main conclusion from assessing the results of forecasting Caspian level fluctuations can be drawn as follows. Although the forecasts were based on completely different approaches (both deterministic and probabilistic), there was not a single reliable forecast. The main difficulty in using deterministic forecasts based on the sea water balance equation is the lack of development of the theory and practice of ultra-long-term climate change forecasts over large areas.

When sea levels dropped in the 1930s to 1970s, most researchers predicted they would fall further. In the last two decades, when sea level rise began, most forecasts predicted an almost linear and even accelerating rise in sea level to -25 and even -20 abs. m and higher at the beginning of the 21st century. Three circumstances were not taken into account. Firstly, the periodic nature of fluctuations in the level of all closed reservoirs. The instability of the Caspian Sea level and its periodic nature is confirmed by an analysis of its current and past fluctuations. Secondly, at a sea level close to – 26 abs. m, the flooding of large bays-sorts that have dried out at a low level will begin northeast coast Caspian Sea - Dead Kultuk and Kaydak, as well as low-lying areas in other places on the coast. This would lead to an increase in the area of shallow waters and, as a consequence, to an increase in evaporation (up to 10 km3/year). With more high level sea, the outflow of water into Kara-Bogaz-Gol will increase. All this should stabilize or at least slow down the level increase. Thirdly, level fluctuations under the conditions of the modern climatic era (the last 2000 years), as shown above, are limited by the risk zone (from – 30 to – 25 abs. m). Taking into account the anthropogenic decrease in runoff, the level is unlikely to exceed the level of 26-26.5 abs. m.

The decrease in average annual levels in the last four years by a total of 0.34 m may indicate that in 1995 the level reached its maximum (- 26.66 abs. m), and a change in the trend of the Caspian level. In any case, the prediction is that sea level is unlikely to exceed 26 absolute. m, apparently, is justified.

In the 20th century, the level of the Caspian Sea changed within 3.5 m, first falling and then rising sharply. This behavior of the Caspian Sea is the normal state of a closed reservoir as an open dynamic system with variable conditions at its inlet.

Each combination of incoming (river flow, precipitation on the sea surface) and outgoing (evaporation from the surface of a reservoir, outflow into the Kara-Bogaz-Gol Bay) components of the Caspian water balance corresponds to its own level of equilibrium. Since the components of the water balance of the sea also change under the influence of climatic conditions, the level of the reservoir fluctuates, trying to reach an equilibrium state, but never reaches it. Ultimately, the trend of changes in the Caspian Sea level in given time depends on the ratio of precipitation minus evaporation in the catchment area (in the basins of the rivers feeding it) and evaporation minus precipitation above the reservoir itself. There is actually nothing unusual about the recent rise in the Caspian sea level by 2.3 m. Such level changes have happened many times in the past and have not caused irreparable damage to the natural resources of the Caspian Sea. The current rise in sea level has become a disaster for the economy of the coastal zone only because of the unreasonable development by man of this risk zone.

Vadim Nikolaevich Mikhailov, Doctor of Geographical Sciences, Professor of the Department of Land Hydrology, Faculty of Geography, Moscow State University, Honored Scientist of the Russian Federation, Full Member of the Academy of Water Sciences. Area of scientific interests: hydrology and water resources, interaction of rivers and seas, deltas and estuaries, hydroecology. Author and co-author of about 250 scientific works, including 11 monographs, two textbooks, four scientific and methodological manuals.

, Kura

42° N. w. 51° east d. HGIOL

Caspian Sea- the largest on Earth closed water, which can be classified as the biggest endorheic lake, or as a full sea, due to its size, and also due to the fact that its bed is composed of the earth’s crust oceanic type. Located at the junction Europe And Asia. Water in the Caspian Sea salty, - from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. Water level subject to fluctuations, according to 2009 data 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 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 island line Chechen- cape Tyub-Karagan, between the Middle and Southern Caspian - along the island line Chilov- Cape Gan-Gulu.

Coast

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

Peninsulas

Absheronsky peninsula, situated on west coast Caspian Sea on the territory of Azerbaijan, at the northeastern end Greater Caucasus, on its territory there are cities Baku And Sumgayit
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 total area approximately 350 square kilometers.

Largest islands:

Bays

Large bays:

Kara-Bogaz-Gol

U east coast located salt Lake Kara-Bogaz-Gol, until 1980, was a bay-lagoon of the Caspian Sea, connected to it by a narrow strait. Built in 1980 dam, separating Kara-Bogaz-Gol from the Caspian Sea, built in 1984 culvert, 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 - Volga , Terek , Sulak , Samur(Russia), Ural , Emba(Kazakhstan), Kura(Azerbaijan), Atrek(Turkmenistan), Sefidrud(Iran). Largest river, flowing into the Caspian Sea - 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 there are cities - Lagan , Makhachkala , Kaspiysk , Izberbash , Dagestan Lights and the most Southern City Russia Derbent. port city The Caspian Sea is also considered Astrakhan, which, however, is not located on the shores of the Caspian Sea, but in Volga delta, 60 kilometers from north coast 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. In the same time Northern part The Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

Vegetable world

The flora of the Caspian Sea and its coast is represented by 728 species. The predominant plants in the Caspian Sea are seaweed- blue-green, diatoms, red, brown, charophytes and others, from flowering plants - eelgrass And rupees. 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 the earth's crust oceanic type. 13 million l. n. the resulting Alps separated Sarmatian Sea from the Mediterranean. 3.4 - 1.8 million l. n. ( Pliocene) existed Akchagyl Sea, whose deposits have been studied N. I. Andrusov. Originally formed on the site of a dry Pontic Sea, from which Lake Balakhanskoye remains (in the territory of the southern Caspian Sea). The Akchagyl transgression was replaced by the Domashkin regression (a drop of 20 - 40 m from the level of the Akchagyl basin), accompanied by strong desalination 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. Start 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 inversion (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 Khvalynsky II basin (level up to 50 m) was replaced at the beginning of the Holocene by a short-term Enotaevsky regression (from −45 to −110 m), coinciding in time with the end preboreal and the beginning boreal. The Enotayevskaya regression gave way to the Late Khvalynskaya transgression (0 m). The Late Khvalynian transgression gave way to Holocene(approx. 9-7 thousand years ago or 7.2-6.4 thousand years ago) by Mangyshlak regression (from −50 to −90 m). The Mangyshlak regression gave way to the first phase of interglacial cooling and humidification ( Atlantic period) Novo-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. On the Caspian Sea there are ferry crossings, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with Sea of Azov across the rivers Volga, Don and Volga-Donskoy Canal.

Fishing and seafood production

Fishing (sturgeon , bream , carp , zander , sprat), caviar production, as well as fishing seal. More than 90 percent of the world's sturgeon catch occurs in the Caspian Sea. In addition to industrial production, the Caspian Sea is thriving illegal mining sturgeon and their caviar.

Recreational resources

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

Ecological problems

Ecological problems The Caspian Sea is associated with water pollution as a result of oil production and transportation on the continental shelf, the 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.

Legal status

After the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of resources of the Caspian shelf - 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 Sea along the median line, Iran- on the division of the Caspian Sea 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 should not automatically apply to the Caspian Sea, in particular the provisions UN Convention on the Law of the Sea 1982. 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.