How old is the Caspian Sea. Seas of Russia - Caspian Sea

This is how the Mediterranean Sea was formed, which then included the current Azov, Black and Caspian Sea. On the site of the modern Caspian, a huge Caspian lowland was formed, the surface of which was almost 30 meters below the water level in the World Ocean. When the next rise of land began to take place at the place of formation Caucasus mountains, The Caspian Sea was finally cut off from the ocean, and in its place a closed drainless reservoir was formed, which today is considered the largest inland sea on the planet. However, some scientists call this sea a giant lake.
A feature of the Caspian Sea is the constant fluctuation of the level of salinity of its water. Even in different areas of this sea, the water has different salinity. This was the reason why fish and crustaceans dominate in the Caspian Sea, which more easily tolerate fluctuations in water salinity.

Since the Caspian is completely isolated from the ocean, its inhabitants are endermics, i.e. always live in its water area.

The fauna of the Caspian Sea can be conditionally divided into four groups.

The first group of animals includes the descendants of ancient organisms that inhabited Tethys about 70 million years ago. Such animals include Caspian gobies (golovach, Knipovich, Berg, bubyr, pugolovka, Baer) and herring (Kessler, Brazhnikov, Volga, shad, etc.), some mollusks and most crustaceans (long-sexed crayfish, orthemia crustacean, etc.). Some fish, mainly herring, periodically enter the rivers flowing into the Caspian to spawn, many never leave the sea. Gobies prefer to live in coastal waters, often found in estuaries.
The second group of animals of the Caspian Sea is represented by arctic species. penetrated into the Caspian Sea from the north in the postglacial period. These are such animals as the Caspian seal (Caspian seal), fish - Caspian trout, white salmon, nelma. Of the crustaceans, this group is represented by mysid crustaceans, similar to small shrimps, tiny sea cockroaches, and some others.
The third group of animals inhabiting the Caspian includes species that independently or with the help of humans moved here from mediterranean sea. These are mollusks mitisyaster and abra, crustaceans - amphipods, shrimp, Black Sea and Atlantic crabs and some types of fish: golden mullet (sharp nose), needle fish and Black Sea kalk (flounder).

And, finally, the fourth group - freshwater fish that penetrated into the Caspian Sea from fresh rivers and turned into marine or anadromous, i.e. periodically rising into the rivers. Some of the typically freshwater fish also occasionally enter the Caspian. Among the fish of the fourth group are catfish, pike perch, barbel, red-lipped asp, Caspian fish, Russian and Persian sturgeon, beluga, stellate sturgeon. It should be noted that the Caspian Sea basin is the main habitat of sturgeons on the planet. Almost 80% of all sturgeons in the world live here. Barbels and fish are also valuable commercial fish.

As for sharks and other fish that are predatory and dangerous to humans, they do not live in the Caspian Sea-Lake.

V. N. MIKHAILOV

The Caspian Sea is the largest on the planet drainless lake. This body of water is called the sea for its huge size, brackish water and sea-like regime. The level of the Caspian Sea-lake lies much lower than the level of the World Ocean. At the beginning of 2000, he had a mark of about - 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. Average and maximum depth 208 and 1025 m respectively.

The Caspian Sea is elongated from south to north (Fig. 1). The Caspian washes the shores of Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran. The reservoir is rich in fish, its bottom and banks are rich in oil and gas. The Caspian Sea is quite well studied, but many mysteries remain in its regime. The most characteristic feature of the reservoir is the instability of the level with sharp drops and rises. The last rise in the level of the Caspian took place before our eyes from 1978 to 1995. It gave rise to many rumors and speculation. Numerous publications appeared in the press, which spoke about catastrophic floods and ecological catastrophe. It was often written 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 such behavior of the Caspian Sea?

WHAT HAPPENED TO THE CASPIAN IN THE 20TH CENTURY

Systematic observations over the level of the Caspian Sea were started in 1837. In the second half of the 19th century, the average annual values of the Caspian Sea level were in the range of marks from -26 to -25.5 abs. m and showed a slight downward trend. This trend continued into the 20th century (Fig. 2). In the period from 1929 to 1941, the 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 mark for 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 a mark of 26.66 abs. m. In the next four years, the average sea level decreased by almost 30 cm. Its average marks 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 advancement coastline towards the sea, the formation of wide beaches. The latter was perhaps the only positive consequence of the level drop. There were many more negative consequences. With a decrease in the level, the areas of forage land for fish stocks in the northern Caspian have decreased. The shallow estuarine coast of the Volga began to quickly overgrow with aquatic vegetation, which worsened the conditions for the passage of fish to spawn in the Volga. Catches of fish, especially valuable species such as sturgeon and sterlet, have sharply decreased. Shipping began to suffer damage due to the fact that the depths in the approach channels decreased, especially near the Volga delta.

The rise in the level 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 a low level.

Many sectors of the economy began to suffer damage. Significant territories turned out to be in the zone of flooding and flooding, especially in the northern (flat) part of Dagestan, in Kalmykia and Astrakhan region. The cities of Derbent, Kaspiysk, Makhachkala, Sulak, Caspian (Lagan) and dozens of other smaller settlements suffered from the level rise. Significant areas of agricultural land have been flooded and flooded. Roads and power lines, engineering structures of industrial enterprises and public utilities are being destroyed. A threatening situation has developed with fish-breeding enterprises. Abrasion processes in the coastal zone and the impact of surges have intensified sea water. In recent years, the flora and fauna of the seashore and the coastal zone of the Volga delta suffered significant damage.

In connection with the increase in depth in the shallow waters of the Northern Caspian and the reduction in the areas occupied in these places by aquatic vegetation, 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 the rising sea level made us speak of an ecological catastrophe. The development of measures to protect national economic objects and settlements from the advancing sea began.

HOW UNUSUAL IS CURRENT CASPIAN BEHAVIOR?

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

It is proved 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. In this period of time in the history of the Caspian, four stages are distinguished: Baku, Khazar, Khvalyn and New Caspian (Fig. 3). Each stage included several transgressions and regressions. The Baku transgression occurred 400-500 thousand years ago, the sea level rose to 5 abs. m. During the Khazar stage, there were two transgressions: the early Khazar (250-300 thousand years ago, the maximum level is 10 abs. m) and the late Khazar (100-200 thousand years ago, the highest level is 15 abs. m). The Khvalyn stage in the history of the Caspian included two transgressions: the largest for the Pleistocene period, the early Khvalyn (40-70 thousand years ago, the maximum level is 47 abs. m, which is 74 m higher than the modern one) and the late Khvalyn (10-20 thousand years ago, the rise level up to 0 abs. m). These transgressions were separated by a deep Enotaevskaya regression (22-17 thousand years ago), when the 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 subatlantic epoch of the Holocene (risk zone). I-IV - stages of the New Caspian transgression; M - Mangyshlak, D - Derbent regression

Significant fluctuations in the level of the Caspian 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, a level decrease to -50 abs. m), five stages of the New Caspian transgression were noted, separated by small regressions (Fig. 4). Following sea level fluctuations, its transgressions and regressions, the outline of the reservoir also changed (Fig. 5).

Over the historical time (2000 years), the range of changes 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 that has passed since the Derbent regression, the average sea level has 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 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 lowering and rising of the level of the Caspian Sea.

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

Rumors that rising sea levels have caused flooding throughout the Volga Delta have not been 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 the water level in the lower part of the delta during the low water period did not exceed 0.2-0.3 m, and almost did not manifest itself during the flood. At the maximum level of the Caspian Sea in 1995, the backwater from the sea spread along the deepest branch of the Bakhtemir delta for no more than 90 km, and along other branches for no more than 30 km. Therefore, only islands on the seashore and a 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 normal for the Volga delta) and with the unsatisfactory condition of protective dams. The reason for the weak effect of sea level rise on the regime of the Volga delta is the presence of a huge shallow coastal zone, which dampens the effect of the sea on the delta.

With regard to 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, the sea level was higher than at present, and this was not perceived as an ecological disaster. And before the level was even higher. Meanwhile, Astrakhan has been known since the middle of the 13th century, and Sarai-Batu, the capital of the Golden Horde, was located here in the 13th - mid-16th centuries. These and many more settlements on the coast of the Caspian Sea did not suffer from high level standing, since they were located on elevated places and at abnormal flood levels or during surges, people temporarily moved from low places to higher ones.

Why, then, are the consequences of a rise in sea level even to smaller levels now perceived as a catastrophe? The reason for the enormous damage that the national economy suffers is not the rise in the 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 the sea level after 1929, that is, with a decrease in the level below the mark - 26 abs. m. The buildings erected in the risk zone, of course, turned out to be flooded and partially destroyed. Now, when the territory developed and polluted by man is flooded, a dangerous ecological situation is really created, the source of which is not natural processes, but unreasonable economic activity.

ABOUT THE REASONS FOR THE CASPIAN LEVEL FLUCTUATIONS

Considering the issue of the causes of fluctuations in the level of the Caspian Sea, it is necessary to pay attention to the confrontation in this area of two concepts: geological and climatic. Significant contradictions in these approaches were revealed, for example, at the international conference "Caspian-95".

According to the geological concept, two groups of processes are attributed to the causes of changes in the level of the Caspian Sea. The processes of the first group, according to geologists, lead to a change in the volume of the Caspian depression and, as a result, to changes in sea level. Such processes include vertical and horizontal tectonic movements of the earth's crust, accumulation of bottom sediments, and seismic events. The second group includes processes that, as geologists believe, affect the underground runoff into the sea, either increasing it or decreasing it. Such processes are called periodic extrusion or absorption of water, which saturate bottom sediments under the influence of changing tectonic stresses (changes in periods of compression and tension), as well as technogenic destabilization of the subsoil due to 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 depression and underground runoff. However, at present, the quantitative relationship 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 depression. However, if we take into account that the Caspian Sea basin is located within a geologically heterogeneous territory, which results in periodic rather than linear tectonic movements with repeated sign changes, then one should hardly expect a noticeable change in the capacity of the basin. Not in favor of the tectonic hypothesis is the fact that the coastlines of the New Caspian transgressions in all sections of the Caspian coast (with the exception of certain areas within the Apsheron archipelago) are at the same level.

There are no grounds to consider the change in the capacity of its basin due to the accumulation of precipitation as the reason for fluctuations in the level of the Caspian Sea. The rate of filling the basin with bottom sediments, among which the main role is played by river runoff, is estimated, according to modern data, at a value of 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. Maev, firstly, the undisturbed stratification of interstitial waters, indicating the absence of noticeable migrations of waters 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 a large-scale discharge of groundwater capable of affect changes in water levels.

The main evidence of the insignificant role of geological factors at present is a convincing quantitative confirmation of the plausibility of the second, climatic, or rather, water-balance concept of fluctuations in the Caspian level.

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

For the first time, fluctuations in the level of the Caspian Sea were explained by a change climatic conditions(more specifically, the runoff of rivers, evaporation and precipitation on the surface of the sea) by E.Kh. Lenz (1836) and A.I. Voeikov (1884). Later, the leading role of changes in the components of the water balance in sea level fluctuations was again and again proved by hydrologists, oceanologists, physicogeographers and geomorphologists.

The key to most of the studies mentioned is the compilation of the 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, atmospheric 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 is the quotient of dividing the change in the volume of its waters 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 flow of the Volga, Ural, Terek, Sulak, Samur, Kura rivers and visible or effective evaporation, the difference between evaporation and atmospheric precipitation on the sea surface. An analysis of the components of the water balance revealed that the largest contribution (up to 72% of the dispersion) to the level variability comes from the inflow of river waters, and more specifically, the runoff formation zone in the Volga basin. As for the reasons for the change in the flow of the Volga itself, they are associated, as many researchers believe, with the variability of atmospheric precipitation (mainly winter) in the river basin. And the mode of precipitation, in turn, is determined by the circulation of the atmosphere. It has long been proven that the latitudinal type of atmospheric circulation contributes to an increase in precipitation in the Volga basin, while 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 the 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, received by the staff of the State Oceanographic Institute R.E. Nikonova and V.N. Bortnik, are given with the author's clarifications in Table. 1. These data convincingly prove that the main reasons for 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 apparent evaporation.

Keeping in mind that river runoff is one of the main factors affecting the water balance and, as a result, the level of the Caspian Sea (and the Volga runoff provides at least 80% of the total river runoff in 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 one Volga, measured most accurately. Direct correlation of these quantities does not give satisfactory results.

However, the relationship between the sea level and the Volga runoff is well traced if the river runoff is not taken into account for each year, but the ordinates of the difference integral runoff curve are taken, that is, the sequential sum of the normalized deviations of the 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) makes it possible to reveal their similarity.

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

The presented 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 above all, the reduction in river flow due to its irretrievable losses for filling reservoirs, evaporation from the surface of artificial reservoirs, and water withdrawal for irrigation. It is believed that since the 1940s, irretrievable water consumption has been steadily increasing, which has led to a reduction in the inflow of river waters 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 1980s, the difference between the actual sea level and the restored (natural) level reached almost 1.5 m. about 26 km3/year). If it were not for the withdrawal of river runoff, then the rise in sea level would have begun not at the end of the 70s, but at the end of the 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 them were in the Volga). Such an increase in irretrievable losses of river runoff should have lowered the level of the Caspian by more than 0.5 m by 2000. In connection with the assessment of the impact of irreversible water consumption on the level of the Caspian, we note the following. First, estimates of water withdrawal volumes and evaporation losses from the surface of reservoirs in the Volga basin found in the literature are apparently significantly overestimated. Secondly, forecasts of water consumption growth turned out to be erroneous. The forecasts included the rate 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. 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 to 24 km3/year). Therefore, the "anthropogenic" difference between the natural and actual sea levels is currently not as large as predicted.

ON POSSIBLE FLUCTUATIONS OF THE CASPIAN 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 the assessment of the results of forecasting fluctuations in the level of the Caspian 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 forecasts of climate change over large areas.

When the sea level decreased in the 30-70s, most researchers predicted its further fall. In the last two decades, when sea level rise began, most forecasts predicted an almost linear and even accelerating rise in level to -25 and even -20 abs. m and above at the beginning of the XXI century. In this case, three factors were not taken into account. First, the periodic nature of fluctuations in the level of all endorheic reservoirs. The instability of the Caspian level and its periodic nature are confirmed by the analysis of its current and past fluctuations. Secondly, at sea level close to - 26 abs. m, the flooding of large sor bays on the northeastern coast of the Caspian Sea - Dead Kultuk and Kaydak, as well as low-lying territories in other places of the coast, which have dried up at a low level, will begin. This would lead to an increase in the area of shallow waters and, as a consequence, an increase in evaporation (up to 10 km3/year). With a higher sea level, the outflow of water to Kara-Bogaz-Gol will increase. All this should stabilize or at least slow down the level growth. Thirdly, level fluctuations under the conditions of the modern climatic epoch (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 mark of 26-26.5 abs. m.

The decrease in average annual levels in the last four years by a total of 0.34 m, possibly indicates 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 that sea level is unlikely to exceed 26 abs. m, apparently justified.

In the 20th century, the level of the Caspian Sea changed within 3.5 m, first dropping and then rising sharply. Such 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 runoff, precipitation on the sea surface) and outgoing (evaporation from the surface of the reservoir, outflow to 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 changing the level of the Caspian in given time depends on the ratio of precipitation minus evaporation in the watershed (in the basins of the rivers that feed it) and evaporation minus precipitation over the reservoir itself. There is really nothing unusual about the recent rise of the Caspian Sea level by 2.3 m. Such level changes have occurred many times in the past and did not cause irreparable damage to the natural resources of the Caspian. The current rise in sea level has become a catastrophe for the economy of the coastal zone only because of the unreasonable development of this risk zone by man.

Vadim Nikolaevich Mikhailov, Doctor of Geography, Professor of the Department of Terrestrial Hydrology of the Faculty of Geography of Moscow State University, Honored Worker of Science of the Russian Federation, full member of the Academy of Water Management 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.

Caspian Sea is a unique ecological system. It is the largest lake on planet Earth. Diverse biosphere, beautiful nature and the wealth of natural resources make it attractive in every aspect.

Caspian Sea: description, photo and video

Many people wonder what is the area of the Caspian Sea. It is quite difficult to answer this question, since this parameter varies depending on seasonality. For example, when the level of the water surface is at around 27 meters, the reservoir covers an area of 370 thousand square kilometers. This is almost 45 percent of the volume of freshwater lakes on Earth.

The Caspian also has a non-uniform depth. In the north, maximum depth of the Caspian Sea only about 25 meters, and the average is within 4 meters. The southern region, on the contrary, is very deep - 1025 kilometers. This is the third indicator in the world among lakes, after Tanganyika and. Scientists cannot yet name the exact reasons for such fluctuations in the Caspian Sea. Among the most likely versions is climate change and the earth's crust in the region.

Caspian Sea - Azerbaijan (Baku)

Since the lake is not only an industrial reservoir, but also a recreational one, the water temperature in the Caspian Sea is also of great interest. In winter, the lake experiences significant temperature fluctuations. On the south side, it is kept at around 11 degrees, and in the north it can drop to 0.5 and below. Sometimes glaciation can be observed in this region.

During the summer period, which lasts here from early June to mid-September, the temperature is approximately the same throughout the reservoir. In the upper layers, the average values are kept within 26-27 degrees, and in shallow water the reservoir can heat up to 32. The water is slightly salty, but the saturation depends on the regional factor and may change. The largest concentration is in the west and south, and in the northern part, thanks to freshwater rivers, it is the smallest. The local climate is also changeable.

The lake is located in three climatic zones at once:

continental;
moderate;
subtropical.

Summer in the region is quite hot. The thermometer can reach up to 44 degrees Celsius. In winter, in the south, these figures fluctuate up to +10, and in the north - up to -10. The Caspian Sea on the map has quite even shores, but in fact, its borders are very indented with river mouths, peninsulas and straits. The length of the coast, taking into account the islands, is 7 thousand kilometers. In the north, the coast is low-lying, and marshland caused by channels is common on it. In the east, limestones are common, flowing into semi-deserts.

There are approximately 50 islands on the territory of the lake. The largest of them:

Seals;
Boyuk-Zira;
Chechen;
Ogurchinsky;
Ashur-Ada.

Among the numerous bays, Kara-Bogaz-Gol can be noted. Until the end of the century before last, it was a kind of lagoon, but in 1980 the construction of a dam began here, because of this, the amount of water entering the lake decreased. To date, the strait has been restored.

What rivers flow into the Caspian Sea? The lake feeds a large number of rivers, the largest of which are:

Volga;
Sulak (Pro);
Terek;
Ural (Pro).

Every year they bring hundreds of cubic meters of fresh water into the lake.

The region has been actively developed for many centuries. Today on the Caspian Sea there are major ports linking trade routes. Of the Russian ones, the most important are Astrakhan and Makhachkala. Oil production is also carried out in the Caspian Sea. According to experts, the oil resources of the region are about 10 billion tons. There are also gas reserves here.

The Caspian Lake is a great place to relax. Local beaches amaze everyone who comes here. The quality of recreation on the Caspian Sea is in no way inferior. Pleasant climate, comfortable beaches and fresh air - all this the Caspian is ready to give to tourists. For those who decide to visit the Caspian Sea, the prices for holidays can pleasantly surprise you. For a low cost, you can get high-quality service.

Popular cities include: resorts of the Caspian Sea:

Makhachkala;
Kaspiysk;
Astrakhan;
Lagan;
Derbent;
Dagestan lights.

Derbent is very attractive from a historical point of view. Astrakhan allows you to enjoy outdoor activities and fishing, and Makhachkala attracts with comfortable and equipped beaches. Rest on the Caspian Sea in Russia allows you to restore your health and relax from the bustle of the city. Among foreign resorts, the most popular are Baku (Azerbaijan), Avaza (Turkmenistan) and Aktau.

Caspian Sea on the map

Where is the Caspian Sea located? It is located on the continent of Eurasia. It is interesting that his east coast located in Asia, and the western - in Europe. Conventionally, the sea is divided into several parts:

Northern Caspian;
South Caspian;
Middle Caspian.

Of these, only the North Caspian is a sea shelf. It contains only 1 percent of the total volume of water and ends at Chechen Island, located near the Kizlyar Bay.

Which countries are washed by the Caspian Sea? There are 5 states on the shore of the lake:

Azerbaijan;
Iran;
Turkmenistan;
Kazakhstan;
Russia.

The largest coastline runs through the territory of Kazakhstan, in second place, according to this indicator, is Russia. The coast of Azerbaijan has the smallest length, but it owns the largest port - Baku.

There are also other large settlements on the coast of the salt reservoir:

Anzali (Iran) - 111 thousand people;
Aktau (Kazakhstan) - 178 thousand people;
Atyrau (Russia) - 183 thousand people

Astrakhan also belongs to the coastal cities of the Caspian Sea, although the city is located 69 kilometers from the coast. Among the rest Russian cities on the seashore one can note Makhachkala, Derbent and Kaspiysk.

Caspian Sea or lake?

The Caspian Sea is a geographical feature, the essence of which does not quite correlate with its name.

Why is the Caspian Sea considered a lake? Caspian Sea It is an endorheic and closed reservoir. It receives water from rivers and has no connection with oceans and other seas. Although the water here is salty, this figure is much lower than that of other seas. International maritime laws do not apply to the Caspian Sea.

On the other hand, the Caspian is quite large in size, which differs from traditional ideas about lakes. Even Baikal, and even more so, is inferior to it in terms of area. There are no other lakes in the world whose coast belongs to five states at the same time. The bottom structure is also very similar to the ocean type. With a high degree of probability, the waters of the Caspian Sea flowed into the Mediterranean Sea many centuries ago, but due to drying and tectonic processes, they were separated.

The water area of the Caspian Sea is rich in islands, the size of which, even by international standards, is quite large.

Nature of the Caspian Sea

One of the most interesting mysteries of the Caspian Sea is the population of seals living on the territory of the lake, which are a small variety of those that live in the cold northern waters. However, their appearance on the coast, at least suggests that these places are beginning to recover ecologically after the negative consequences of oil production.

vegetable and animal world The Caspian Sea is very diverse. The underwater ecosystem boasts a large number of crustaceans, mollusks, gobies, herring and sprat. Many species are endemic, meaning they only live in this region and nowhere else.

Freshwater species also live in the waters of the lake. They were able to adapt to salt water. These are primarily carp and perch fish. At the end of the ice age, arctic fish and invertebrates penetrated here. In the 40s of the last century, the waters of the Caspian Sea were deliberately populated with mullet, nereis and abra, which are the food base for sturgeons.

Fish processing plants operate in the vicinity of the Caspian Sea, as well as purification stations designed to ensure water cycles. Systematic work is also underway to breed many varieties of underwater abodes that have industrial value. The region is of great interest for fishing tourism. This holiday is especially popular in the Astrakhan region on the Caspian Sea.

The flora of the lake is represented by more than 700 plant species. Some of them grow on land, others in water. Phytoplankton of the Caspian Sea consists of both marine and freshwater algae. According to rough estimates, about 440 species of algae live in the reservoir.

Historical facts

The Caspian coast was once home to ancient civilization, which subsequently disappeared. There is an opinion that in the vicinity of Dagestan, the waters hide Itil from human eyes - the capital city of the Khazar Khaganate, which completely disappeared in the 12th century. In Derbent, there is still a wall from an ancient settlement, going to a depth of 300 meters. For what purpose it was built and who built it is a mystery.

Another interesting feature of the Caspian Sea is the Sabail citadel, located under water in the Baku Bay. The building was flooded during an earthquake that occurred in 1306. In 1723, the upper part of the highest tower became visible above the water surface - this was the result of a decrease in the water level. Today, the fortress is again hidden in the depths of the Caspian Sea, although in sunny weather it can be seen in the water column.

The territory of the Caspian Sea was an "apple of discord" between the adjacent countries. Disputes over the distribution of the possessions and resources of the lake have been going on for 22 years. In 2018, the countries finally came to a common denominator. On August 12, the Convention on the Legal Status of the Caspian Sea was signed. Prior to this, in the legal field, regulation was carried out on the basis of the Soviet-Iranian agreements defining the Caspian as a closed body of water, and each border state had an independent right to a 10-mile zone. The rest of the lake was divided equally.

How the Caspian Sea was divided? The new agreement assigns 15 miles of territorial waters to each state. Also, the bottom of the Caspian Sea is divided into sectors, as happens with the seas, and the sovereignty of the water column is established on the principle of a lake.

For the current day Caspian Sea is an economically important region. Without it, it is impossible to imagine Eurasia, including Russia. Everyone should visit the Caspian Sea, and the protection of the reservoir should be carried out at the state level. Only by joint efforts can this natural pearl be preserved.

, Kazakhstan, Turkmenistan, Iran , Azerbaijan

Geographical position

Caspian Sea - view from space.

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

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

Coast of the Caspian Sea

Coast of the Caspian Sea in Turkmenistan

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

Peninsulas of the Caspian Sea

Ashur-Ada
Garasu
Zyanbil
Hara Zira
Sengi-Mugan
Chygyl

Bays of the Caspian Sea

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

Cities on the coast of the Caspian Sea

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

Physiography

Area, depth, volume of water

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

Water level fluctuations

Vegetable world

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

History of the Caspian Sea

Origin of the Caspian Sea

Anthropological and cultural history of the Caspian Sea

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

Exploration of the Caspian Sea

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

Economy of the Caspian Sea

Oil and gas

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

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

Shipping

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

Fishing and seafood

The purpose of the Convention is "to protect the marine environment of the Caspian Sea from pollution, including the protection, conservation, restoration, sustainable and rational use of its biological resources." The Convention entered into force on 12 August 2006.

Security issues

The head of the strategic planning service of the Association for Border Cooperation (Moscow), Russian political expert Alexander Sobyanin believes that security in the Caspian and guarantees of the neutrality of the sea will be observed only if the Russian fleet dominates in it.

He noted in an interview with the SalamNews news agency: “A delicate balance and the absence of war is possible only and exclusively with the overwhelming superiority of one country - Russia. Any step towards bringing the capabilities of the flotillas of other countries closer to the capabilities of the Caspian flotilla will upset the unstable balance and increase the possibility of military action. Such a task is still being carried out - the capabilities of the Caspian military flotilla [of Russia] exceed the combined capabilities of the flotillas of the other Caspian countries.

The Caspian Sea is the most big lake On the Earth. It is called the sea because of its size and bed, which is folded like an ocean basin. The area is 371,000 square meters, the depth is 1025 m. The list of rivers flowing into the Caspian Sea includes 130 names. The largest of them are: Volga, Terek, Samur, Sulak, Ural and others.

Caspian Sea

It took 10 million years before the Caspian was formed. The reason for its formation is that the Sarmatian Sea, which lost its connection with the World Ocean, was divided into two reservoirs, which were called the Black and Caspian Seas. Between the latter and the World Ocean stretch thousands of kilometers of waterless path. It is located at the junction of two continents - Asia and Europe. Its length in the north-south direction is 1200 km, west-east - 195-435 km. The Caspian Sea is an internal drainless basin of Eurasia.

Near the Caspian Sea, the water level is below the level of the World Ocean, and besides, it is subject to fluctuations. According to scientists, this is due to many factors: anthropogenic, geological, climatic. At present, the average water level reaches 28 m.

The network of rivers and sewage is unevenly distributed along the coast. Few rivers flow into the part of the sea from the north side: Volga, Terek, Ural. From the west - Samur, Sulak, Kura. East Coast characterized by the absence of permanent streams. Differences in space in the flow of water that rivers bring to the Caspian Sea is an important geographical feature of this reservoir.

Volga

This river is one of the largest in Europe. In Russia, it ranks sixth in size. Regarding the catchment area, it is second only to the Siberian rivers flowing into the Caspian Sea, such as the Ob, Lena, Yenisei, Irtysh. For the source, from where the Volga originates, the key is taken near the village of Volgoverkhovye, Tver Region, on the Valdai Upland. Now there is a chapel at the source, which attracts the attention of tourists, for whom it is a pride to step over the very beginning of the mighty Volga.

A small fast stream gradually gains strength and becomes a huge river. Its length is 3690 km. The source is 225 m above sea level. Among the rivers flowing into the Caspian Sea, the largest is the Volga. Her path runs through many regions of our country: Tver, Moscow, Nizhny Novgorod, Volgograd and others. The territories through which it flows are Tatarstan, Chuvashia, Kalmykia and Mari El. The Volga is the location of millionaire cities - Nizhny Novgorod, Samara, Kazan, Volgograd.

Volga Delta

The main riverbed is divided into channels. A certain shape of the mouth is formed. It's called the delta. Its beginning is the place of separation of the Buzan branch from the bed of the Volga river. The delta is located 46 km north of the city of Astrakhan. It includes channels, branches, small rivers. There are several main branches, but only Akhtuba is navigable. Among all the rivers of Europe, the Volga is distinguished by the largest delta, which is a rich fish region in this basin.

It lies lower than the ocean level, at 28 m. The mouth of the Volga is the location of the southernmost Volga city of Astrakhan, which in the distant past was the capital of the Tatar Khanate. Later, at the beginning of the 18th century (1717), Peter 1 gave the city the status of "the capital of the province of Astrakhan." During his reign, the main attraction of the city, the Assumption Cathedral, was built. Its Kremlin is made of white stone, brought from the capital of the Golden Horde, the city of Saray. The mouth is divided by branches, the largest of which are: Bolda, Bakhtemir, Buzan. Astrakhan is southern city located on 11 islands. Today it is a city of shipbuilders, sailors and fishermen.

Currently, the Volga needs protection. For this purpose, a reserve has been established at the place where the river flows into the sea. The delta of the Volga, the largest river flowing into the Caspian Sea, abounds in unique flora and fauna: sturgeon, lotuses, pelicans, flamingos and others. Immediately after the revolution of 1917, a law was passed on their protection by the state as part of the Astrakhan Reserve.

Sulak River

It is located in Dagestan, flows through its territory. It feeds on the waters of melted snows that flow down from the mountains, as well as tributaries: Small Sulak, Chvakhun-bak, Akh-su. Water also enters Sulak through a canal from the Aksai and Aktash rivers.

The source is formed by the confluence of two rivers that originate in the basins: Didoyskaya and Tushinskaya. The length of the Sulak River is 144 km. Its pool has a fairly large area - 15,200 square meters. It flows through the canyon with the same name as the river, then through the Akhetlinsky gorge and finally comes to the plane. Going around the Agrakhan Bay from the south side, Sulak flows into the sea.

The river provides drinking water for Kaspiysk and Makhachkala, and is home to hydroelectric power plants, the urban-type settlements of Sulak and Dubki, and the small town of Kizilyurt.

Samur

The river got its name not by chance. The name translated from the Caucasian language (one of them) means "middle". Indeed, the border between the states of Russia and Azerbaijan is marked along the waterway along the Samur River.

The sources of the river are glaciers and springs, originating in the spurs of the Caucasus Range from the northeast side, not far from Guton Mountain. The height above sea level is 3200 m. Samur has a length of 213 km. The height in the upper reaches and the mouth differs by three kilometers. The catchment basin has an area of almost five thousand square meters.

The places where the river flows are narrow gorges located between mountains of great height, composed of shales and sandstones, which is why the water here is muddy. The Samur basin has 65 rivers. Their length reaches 10 km or more.

Samur: the valley and its description

The valley of this river in Dagestan is the most densely populated region. Derbent is located near the mouth - ancient city peace. The banks of the Samur River are home to twenty or more species of relict representatives of the flora. Endemic, endangered and rare species listed in the Red Book grow here.

In the river delta, a relict forest is comfortably located, which is the only one in Russia. Liana forest is a fairy tale. Huge trees of the rarest and most common species grow here, intertwined with lianas. The river is rich in valuable species of fish: mullet, pike perch, pike, catfish and others.

Terek

The river got its name from the Karachay-Balkar peoples who lived along its banks. They called it "Terk Suu", which means "rushing water" in translation. Ingush and Chechens called it Lomeki - "mountain water".

The beginning of the river is the territory of Georgia, the Zigla-Khokh glacier is a mountain located on a slope Caucasian ridge. It is under glaciers all year round. One of them melts when sliding down. A small stream is formed, which is the source of the Terek. It is located at an altitude of 2713 m above sea level. The length of the river flowing into the Caspian Sea is 600 km. At the confluence with the Caspian, the Terek is divided into many branches, as a result of which a vast delta is formed, its area is 4000 square meters. In some places it is very swampy.

The course in this place has changed several times. The old arms have now been turned into canals. The middle of the last century (1957) was marked by the construction of the Kargaly hydroelectric complex. It is used to supply water to the channels.

How is the Terek replenished?

The river has a mixed supply, but for the upper reaches, water from the melting of glaciers plays an important role, they fill the river. In this regard, 70% of the runoff occurs in spring and summer, that is, at this time the water level in the Terek is the highest, and the lowest - in February. The river freezes if the winters are characterized by a harsh climate, but the freeze-up is unstable.

The river is not distinguished by cleanliness and transparency. The turbidity of the water is large: 400-500 g/m 3 . Every year, the Terek and its tributaries pollute the Caspian Sea, pouring into it from 9 to 26 million tons of various suspensions. This is due to the rocks of which the shores are composed, and they are clayey.

Terek mouth

The Sunzha is the largest tributary flowing into the Terek, the lower reaches of which are measured precisely from this river. By this time, the Terek flows for a long time over the flat terrain, leaving the mountains located behind the Elkhot Gates. The bottom here is composed of sand and pebbles, the current slows down, and in some places stops altogether.

The mouth of the Terek River has an unusual appearance: the channel here is elevated above the valley, along appearance resembles a canal, which is fenced with an embankment of great height. The water level rises above the land level. This phenomenon is due to a natural cause. Since the Terek is a turbulent river, it brings sand and stones in large quantities from the Caucasus Range. Given that the current in the lower reaches is weak, some of them settle here and do not reach the sea. For the inhabitants of the area, sediments are both a threat and a boon. When they are washed away by water, floods of great destructive power occur, this is very bad. But in the absence of floods, the soils become fertile.

Ural River

In antiquity (before the second half of XVIII century) the river was called Yaik. It was renamed into the Russian style by the decree of Catherine II in 1775. Just at this time, the Peasant War was suppressed, the leader of which was Pugachev. The name is still preserved in the Bashkir language, and in Kazakhstan it is official. The Urals are the third longest in Europe, only the Volga and the Danube are larger than this river.

The Ural originates in Russia, on the slope of the Kruglyaya Sopka of the Uraltau Ridge. The source is a spring gushing out of the ground at an altitude of 637 m above sea level. At the beginning of its journey, the river flows in a north-south direction, but after meeting a plateau on the way, it makes a sharp turn and continues to flow in a north-westerly direction. However, beyond Orenburg, its direction again changes to the southwestern, which is considered the main one. Having overcome the winding path, the Ural flows into the Caspian Sea. The length of the river is 2428 km. The mouth is divided into branches and tends to shallow.

The Ural is a river along which the natural water boundary between Europe and Asia passes, with the exception of the upper reaches. This is an internal European river, but its upper reaches to the east of the Ural Range are the territory of Asia.

Importance of the Caspian rivers

The rivers flowing into the Caspian Sea are of great importance. Their waters are used for human and animal consumption, domestic needs, agricultural and industrial needs. Hydroelectric power plants are being built on the rivers, the energy of which is in demand by man for various purposes. River basins are full of fish, algae, shellfish. Even in ancient times, people chose river valleys for future settlements. And now cities and towns are being built on their banks. Rivers plow passenger and transport ships, performing important tasks for the transport of passengers and goods.