Caspian Sea. Where is it located, photos, characteristics, area, holiday resorts. Caspian Sea ~ Seas and Oceans Where is the source of the Caspian Sea

There are still disputes about the status of the Caspian Sea. The fact is that, despite its generally accepted name, it is still the largest endorheic lake in the world. It was called the sea because of the features of the structure of the bottom. It is formed by oceanic crust. In addition, the water in the Caspian Sea is salty. As at sea, there are often storms and strong winds that raise high waves.

Geography

The Caspian Sea is located at the junction of Asia and Europe. In its shape, it resembles one of the letters of the Latin alphabet - S. From south to north, the sea stretches for 1200 km, and from east to west - from 195 to 435 km.

The territory of the Caspian Sea is heterogeneous in its physical and geographical conditions. In this regard, it is conventionally divided into 3 parts. These include the Northern and Middle, as well as the Southern Caspian.

Coastal countries

Which countries is washed by the Caspian Sea? There are only five of them:

1. Russia, located in the northwest and west. The length of the coastline of this state along the Caspian Sea is 695 km. Kalmykia, Dagestan and the Astrakhan region, which are part of Russia, are located here.
2. Kazakhstan. It is a country on the shores of the Caspian Sea, located in the east and northeast. The length of its coastline is 2320 km.
3. Turkmenistan. The map of the Caspian states indicates that this country is located in the southeast of the water basin. The length of the line along the coast is 1200 km.
4. Azerbaijan. This state, stretching 955 km along the Caspian Sea, washes its shores in the southwest.
5. Iran. A map of the Caspian states indicates that this country is located on the southern shores of an endorheic lake. At the same time, its length maritime boundaries is 724 km.

Is the Caspian Sea?

The dispute over what to call this unique body of water has not yet been resolved. And it is important to answer this question. The fact is that all countries on the Caspian Sea have their own interests in this region. However, the governments of five states have not been able to resolve the question of how to divide this huge body of water for a long time. The most important controversy revolved around the name. Is the Caspian Sea a sea or a lake? Moreover, the answer to this question is of no more interest to geographers. First of all, politicians need it. This is due to the application of international law.

Caspian states such as Kazakhstan and Russia believe that their borders in this region are washed by the sea. In this regard, representatives of the two indicated countries insist on the application of the UN Convention adopted in 1982. It concerns the law of the sea. The provisions of this document state that coastal states are allocated a twelve-mile water zone along it. In addition, the country is granted the right to economic maritime territory. It is located two hundred miles away. The coastal state also has rights to However, even the widest part of the Caspian Sea is narrower than the distance specified in the international document. In this case, the middle line principle can be applied. At the same time, the Caspian states, which have the greatest length of coastal borders, will receive a large maritime territory.

Iran has a different opinion on this matter. Its representatives believe that the Caspian Sea should be divided fairly. In this case, all countries will get twenty percent of the maritime territory. The position of official Tehran can be understood. With this solution to the issue, the state will manage a larger zone than when dividing the sea along the middle line.

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

Is the Caspian a lake?

Adherents of this point of view proceed from the fact that the reservoir, located at the junction of Asia and Europe, is closed. In this case, it is impossible to apply a document on the norms of international maritime law to it. Proponents of this theory are convinced that they are right, citing the fact that the Caspian Sea does not have a natural connection with the waters of the World Ocean. But here another difficulty arises. If the lake is the Caspian Sea, the boundaries of states according to what international standards should be determined in its water spaces? Unfortunately, such documents have not yet been developed. The fact is that the issues of the international lake have not been discussed anywhere by anyone.

Is the Caspian Sea a unique body of water?

In addition to those listed above, there is another, third point of view on the ownership of this amazing body of water. Its supporters are of the opinion that the Caspian Sea should be recognized as an international water basin, belonging equally to all countries bordering it. In their opinion, the resources of the region are subject to joint exploitation by countries bordering the reservoir.

Solving security problems

The Caspian states are doing everything possible to eliminate all existing disagreements. And in this matter, positive developments can be noted. One of the steps towards solving problems related to the Caspian region was the agreement signed on November 18, 2010 between all five countries. It concerns issues of security cooperation. In this document, the countries agreed on joint activities to eliminate terrorism, drug trafficking, smuggling, poaching, money laundering, etc. in the region.

Environmental protection

Particular attention is paid to solving environmental issues. The territory in which the Caspian states and Eurasia are located is a region under the threat of industrial pollution. Kazakhstan, Turkmenistan and Azerbaijan dump waste from energy exploration and production into the waters of the Caspian Sea. Moreover, it is in these countries that a large number of abandoned oil wells that are not exploited due to their unprofitability, but nevertheless continue to have an adverse impact on the environmental situation. As for Iran, it dumps agricultural waste and sewage into sea waters. Russia threatens the ecology of the region with industrial pollution. It's connected with economic activity, which unfolded in the Volga region.

Countries on the Caspian Sea have made some progress in addressing environmental problems. Thus, since August 12, 2007, the Frame Convection has been in force in the region, with the goal of protecting the Caspian Sea. This document develops provisions on the protection of biological resources and regulation of anthropogenic factors affecting the aquatic environment. According to this convection, the parties must interact when carrying out measures to improve the environmental situation in the Caspian Sea.

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

• Protocol on cooperation, response and regional preparedness in the event of oil pollution incidents.
• Protocol concerning the protection of the region against pollution from land-based sources.

Development of gas pipeline construction

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

Holding the first summit

Countries on the Caspian Sea are constantly looking for ways to solve the problems that have arisen in this Eurasian region. For this purpose, special meetings of their representatives are organized. Thus, the first summit of the heads of the Caspian states took place in April 2002. Its venue was Ashgabat. However, the results of this meeting did not live up to expectations. The summit was considered unsuccessful due to Iran's demands to divide the sea area into 5 equal parts. Other countries categorically opposed this. Their representatives defended their own point of view that the size of national waters should correspond to the length that coastline states.

The failure of the summit was also provoked by a dispute between Ashgabat and Baku over the ownership of three oil fields located in the center of the Caspian Sea. As a result, the heads of five states did not develop a consensus on any of all the issues raised. However, an agreement was reached to hold a second summit. It was supposed to take place in 2003 in Baku.

Second Caspian Summit

Despite the existing agreements, the planned meeting was postponed every year. The heads of the Caspian states gathered for the second summit only on October 16, 2007. It was held in Tehran. At the meeting, current issues related to determining the legal status of the unique body of water that is the Caspian Sea were discussed. The borders of states within the division of the water area were previously agreed upon during the development of the draft of the new convention. Problems of security, ecology, economics and cooperation of coastal countries were also raised. In addition, the results of the work that the states carried out after the first summit were summed up. In Tehran, representatives of the five states also outlined ways for further cooperation in the region.

Meeting at the third summit

Once again, the heads of the Caspian countries met in Baku on November 18, 2010. The result of this summit was the signing of an agreement to expand cooperation regarding security issues. During the meeting, it was pointed out that which countries are washed by the Caspian Sea, only those should ensure the fight against terrorism, transnational crime, weapons proliferation, etc.

Fourth summit

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

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

V. N. MIKHAILOV

The Caspian Sea is the largest on the planet endorheic lake. 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, the formation 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 areas were in the flood and flood zone, especially in the northern (plain) part of Dagestan, Kalmykia and the 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 last years The flora and fauna of the seaside and coastal zone of the Volga delta suffered significant damage.

Due to the increase in depth in the shallow waters of the Northern Caspian Sea 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 abs. 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 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 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. The natural conditions of the 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 other 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 that a territory developed and polluted by humans is being flooded, a dangerous situation is indeed being created. ecological situation, 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 changes in the volume of the 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 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 not supported by the fact that the coastlines of the 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 in climatic conditions (more specifically, river flow, evaporation and precipitation on the sea surface) by 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-sors on the north-eastern coast of the Caspian Sea - Dead Kultuk and Kaydak, as well as low-lying areas in other places on the coast - will begin to flood, which have dried out at low levels. 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). At a higher sea level, 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.

The Caspian Sea is the largest enclosed body of water on planet Earth, located on the continent of Eurasia - in the border territory of the states of Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. In fact, it is a giant lake left after the disappearance of the ancient Tethys Ocean. Nevertheless, there is every reason to consider it as an independent sea (this is indicated by its salinity, large area and considerable depth, a bottom made of oceanic crust and other signs). In terms of maximum depth, it is the third among closed reservoirs - after lakes Baikal and Tanganyika. In the northern part of the Caspian Sea (a few kilometers from northern shore- parallel to it) runs geographical boundary between Europe and Asia.

Toponymy

• Other names: throughout the history of mankind, the Caspian Sea has had about 70 different names among different peoples. The most famous of them: Khvalynskoye or Khvalisskoye (took place during the Ancient Rus', arose from the name of the people praises, who lived in the Northern Caspian region and traded with the Russians), Hyrcanian or Djurdzhanian (descended from alternative names the city of Gorgan, located in Iran), Khazarskoye, Abeskunskoye (after the name of the island and city in the Kura delta - now flooded), Saraiskoye, Derbentskoye, Sikhay.
• Origin of name: according to one hypothesis, its modern and most ancient name, The Caspian Sea received from a tribe of nomadic horse breeders Caspian Sea, who lived in the 1st millennium BC on the southwestern coast.

Morphometry

• Catchment area: 3,626,000 km².
• Mirror area: 371,000 km².
• Coastline length: 7,000 km.
• Volume: 78,200 km³.
• Average depth: 208 m.
• Maximum depth: 1,025 m.

Hydrology

• Availability of permanent flow: no, drainless.
• Tributaries:, Ural, Emba, Atrek, Gorgan, Kheraz, Sefidrud, Astarchay, Kura, Pirsagat, Kusarchay, Samur, Rubas, Darvagchay, Ulluchay, Shuraozen, Sulak, Terek, Kuma.
• Bottom: very diverse. At shallow depths, sandy soil with an admixture of shells is common; in deep-sea areas, it is silty. In the coastal strip there may be pebbly and rocky places (especially where mountain ranges adjoin the sea). In the estuarine areas, the underwater soil consists of river sediments. The Kara-Bogaz-Gol Bay is notable for the fact that its bottom is a thick layer of mineral salts.

Chemical composition

• Water: salty.
• Salinity: 13 g/l.
• Transparency: 15 m.

Geography

Rice. 1. Map of the Caspian Sea basin.

• Coordinates: 41°59′02″ n. latitude, 51°03′52″ e. d.
• Height above sea level:-28 m.
• Coastal landscape: due to the fact that the coastline of the Caspian Sea is very long, and it itself is located in different geographical areas— The coastal landscape is diverse. In the northern part of the reservoir, the banks are low, swampy, and in the deltas of large rivers, they are cut by numerous channels. Eastern Shores for the most part limestone - desert or semi-desert. Western and southern shore adjacent to mountain ranges. The greatest ruggedness of the coastline is observed in the west - in the area of ​​the Absheron Peninsula, as well as in the east - in the area of ​​the Kazakh and Kara-Bogaz-Gol bays.
• Settlements on the banks:
  • Russia: Astrakhan, Derbent, Kaspiysk, Makhachkala, Olya.
  • Kazakhstan: Aktau, Atyrau, Kuryk, Sogandyk, Bautino.
  • Turkmenistan: Ekerem, Karabogaz, Turkmenbashi, Khazar.
  • Iran: Astara, Balboser, Bender-Torkemen, Bender-Anzeli, Neka, Chalus.
  • Azerbaijan: Alyat, Astara, Baku, Dubendi, Lankaran, Sangachali, Sumgayit.

Interactive map

Ecology

The ecological situation in the Caspian Sea is far from ideal. Almost all large rivers flowing into it are polluted by wastewater from industrial enterprises located upstream. This could not but affect the presence of pollutants in the waters and bottom sediments of the Caspian Sea - over the past half century, their concentration has increased significantly, and the content of some heavy metals has already exceeded permissible standards.

In addition, the waters of the Caspian Sea are constantly polluted by domestic wastewater from coastal cities, as well as during oil production on the continental shelf, and during its transportation.

Fishing on the Caspian Sea

• Types of fish:
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
• Artificial settlement: not all of the above fish species in the Caspian Sea are native. About 4 dozen species arrived by accident (for example, through canals from the basins of the Black and Baltic Seas), or were intentionally populated by humans. As an example, it is worth citing mullets. Three Black Sea species of these fish - mullet, sharpnose and singil - were released in the first half of the 20th century. The mullet did not take root, but the sharpnose and the singil successfully acclimatized, and by now have settled virtually throughout the entire Caspian waters, forming several commercial herds. At the same time, the fish fatten up faster than in the Black Sea and reach larger sizes. In the second half of the last century (starting from 1962), attempts were also made to introduce such Far Eastern salmon fish as pink salmon and chum salmon into the Caspian Sea. In total, several billion fry of these fish were released into the sea over the course of 5 years. Pink salmon did not survive in the new habitat, chum salmon, on the contrary, successfully took root and even began to enter the rivers flowing into the sea to spawn. However, it was unable to reproduce in sufficient quantities and gradually disappeared. There are still no favorable conditions for its full natural reproduction (there are very few places where spawning and development of fry could successfully occur). To provide them, river reclamation is necessary, otherwise, without human help (artificial collection of eggs and their incubation), the fish will not be able to maintain their numbers.

Fishing spots

In fact, fishing is possible anywhere on the Caspian Sea coast, which can be reached by land or water. What types of fish will be caught depends on local conditions, but to a greater extent on whether the rivers flow here. As a rule, in places where estuaries and deltas are located (especially large watercourses), the water in the sea is greatly desalinated, so freshwater fish (carp, catfish, bream, etc.) usually predominate in the catches; species characteristic of the flowing rivers may also be found. rivers (usachi, shemaya). From marine species in desalinated areas, those for which salinity does not matter (mullet, some gobies) are caught. At certain periods of the year, semi-anadromous and anadromous species can be found here, feeding in the sea and entering rivers to spawn (sturgeon, some herrings, Caspian salmon). In places where there are no flowing rivers, freshwater species are found in slightly smaller numbers, but marine fish also appear, usually avoiding desalinated areas (for example, sea pike perch). Far from the coast, fish are caught that prefer salt water, and deep-sea species.

Conventionally, we can distinguish 9 places or areas that are interesting in terms of fishing:

1. North Shore (RF)- this site is located on the northern coast of the Russian Federation (from the Volga delta to the Kizlyar Bay). Its main features are low salinity of water (the lowest in the Caspian Sea), shallow depth, the presence of multiple shoals, islands, and highly developed aquatic vegetation. In addition to the Volga delta with its numerous channels, bays and eriks, it also includes the estuary coastal area, called the Caspian Peaks. These places are popular among Russian fishermen, and for good reason: the conditions for fish here are very favorable, and there is also a good food supply. The ichthyofauna in these parts may not shine with a wealth of species, but it is distinguished by its abundance, and some of its representatives reach quite considerable sizes. Typically, the bulk of the catches are freshwater fish characteristic of the Volga basin. Most often caught: perch, pike perch, roach (more precisely, its varieties called roach and ram), rudd, asp, sabrefish, bream, silver carp, carp, catfish, pike. Somewhat less common are black bream, silver bream, white-eye, and bluegill. Representatives of sturgeons (sturgeon, stellate sturgeon, beluga, etc.) and salmonids (nelma, brown trout - Caspian salmon) are also found in these places, but their fishing is prohibited.
2. Northwestern coast (RF)- this section covers the western coast of the Russian Federation (from Kizlyar Bay to Makhachkala). The rivers Kuma, Terek and Sulak flow here - they carry their waters both through natural channels and artificial canals. There are bays in this area, some of which are quite large (Kizlyarsky, Agrakhansky). The sea in these places is shallow. Freshwater fish predominate in the catches: pike, perch, carp, catfish, rudd, bream, barbel, etc., and marine species are also caught here, for example, herring (blackback, bellyfish).
3. West Bank (RF)- from Makhachkala to the border of the Russian Federation with Azerbaijan. An area where mountain ranges adjoin the sea. The salinity of the water here is slightly higher than in previous places, therefore, marine species are more common in fishermen’s catches (sea pike perch, mullet, herring). However, freshwater fish are by no means uncommon.
4. West Bank (Azerbaijan)- from the border of the Russian Federation with Azerbaijan along the Absheron Peninsula. Continuation of the area where mountain ranges adjoin the sea. Fishing here is even more similar to typical offshore fishing, with fish such as razorback and mullet and several species of gobies also caught here. In addition to them, there are kutum, herring, and some typically freshwater species, for example, carp.
5. Southwestern coast (Azerbaijan)- from the Absheron Peninsula to the border of Azerbaijan with Iran. Most of this area is occupied by the Kura River delta. The same types of fish that were listed in the previous paragraph are caught here, but freshwater ones are somewhat more common.
6. Northern coast (Kazakhstan)- this area covers north coast Kazakhstan. Here are the Ural delta and state reserve“Akzhaiyk”, therefore fishing directly in the river delta and in some adjacent water areas is prohibited. Fishing can only be done outside the reserve - upstream from the delta, or in the sea - at some distance from it. Fishing near the Ural delta has much in common with fishing at the confluence of the Volga - almost the same species of fish are found here.
7. Northeast coast (Kazakhstan)- from the mouth of the Emba to Cape Tyub-Karagan. Unlike the northern part of the sea, where the water is greatly diluted by large rivers flowing in, its salinity here increases slightly, so those species of fish appear that avoid desalinated areas, for example, sea pike perch, which is fished in Dead Kultuk Bay. Also, other representatives of marine fauna are often found in the catches.
8. Eastern coast (Kazakhstan, Turkmenistan)- from Cape Tyub-Karagan to the border of Turkmenistan and Iran. It is distinguished by the almost complete absence of flowing rivers. The salinity of the water here is at its maximum. Of the fish in these places, marine species predominate; the bulk of the catches are mullet, sea pike perch and gobies.
9. South Bank (Iran)- covers South coast Caspian Sea. Along the entire length of this section, the sea is adjacent to mountain range Elborz. Many rivers flow here, most of which are small streams, there are also several medium-sized and one large river. Of the fish, in addition to marine species, there are also some freshwater, as well as semi-anadromous and anadromous species, for example, sturgeon.

Fishing Features

The most popular and catchy amateur tackle used on the Caspian coast is a heavy spinning rod, converted into a “sea bottom”. It is usually equipped with a durable reel on which a fairly thick fishing line (0.3 mm or more) is wound. The thickness of the fishing line is determined not so much by the size of the fish, but by the mass of a fairly heavy sinker, which is necessary for ultra-long casting (in the Caspian Sea it is widely believed that the farther from the shore the casting point is, the better). After the sinker comes a thinner line - with several leashes. The bait used is shrimp and amphipods that live in coastal algae thickets - if you plan to catch sea fish, or ordinary bait like a worm, chafer larvae and others - if there are freshwater species in the fishing area.

At the mouths of inflowing rivers, other gear can be used, such as a float rod, feeder and traditional spinning rod.

kasparova2 majorov2006 g2gg2g-61 .

Photo 8. Sunset in Aktau.

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

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

Physiographically and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conventional border between the northern and middle parts runs along the line Chechen Island–Cape Tyub-Karagan, and between the middle and southern parts along the line Zhiloy Island–Cape Kuuli.
The shelf of the Caspian Sea is on average limited to depths of about 100 m. The continental slope, which begins below the shelf edge, ends in the middle part at approximately 500–600 m depths, in the southern part, where it is very steep, at 700–750 m.

Northern part The sea is shallow, its average depth is 5–6 m, the maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom topography is complicated by the presence of banks, islands, and grooves.
The middle part of the sea is an isolated basin, the region of maximum depths of which - the Derbent depression - is shifted to the western coast. The average depth of this part of the sea is 190 m, the greatest is 788 m.

The southern part of the sea is separated from the middle by the Absheron threshold, which is a continuation Greater Caucasus. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum sea depth of 1025 m is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.

Shores The Caspian Sea is diverse. In the northern part of the sea they are quite indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy and Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islands and channels, often changing their position. Many small islands and banks are located on other parts of the coastline.
The middle part of the sea has a relatively flat coastline. On the western coast, on the border with the southern part of the sea, is the Absheron Peninsula. To the east of it, the islands and banks of the Absheron archipelago stand out, of which the most large island Residential. The eastern coast of the Middle Caspian is more indented; the Kazakh Gulf with Kenderli Bay and several capes stand out here. The largest bay of this coast is Kara-Bogaz-Gol.

South of the Absheron Peninsula are the islands of the Baku archipelago. The origin of these islands, as well as some of the jars east coast the southern part of the sea is associated with the activity of underwater mud volcanoes lying on the seabed. On east coast There are large bays of Turkmenbashi and Turkmensky, and near it the island of Ogurchinsky.

One of the most striking phenomena of the Caspian Sea is the periodic variability of its level. In historical times, the Caspian Sea had a level lower than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) of sea level, the amplitude of its fluctuations has been almost 4 m, from –25.3 m in the eighties of the 19th century. to –29 m in 1977. In the last century, the level of the Caspian Sea changed significantly twice. In 1929 it stood at about -26 m, and since it had been close to this level for almost a century, this level position was considered to be a long-term or secular average. In 1930 the level began to decline rapidly. By 1941 it had dropped by almost 2 m. This led to the drying out of vast coastal areas of the bottom. The decrease in level, with slight fluctuations (short-term slight rises in level in 1946–1948 and 1956–1958), continued until 1977 and reached a level of –29.02 m, i.e. the level reached its lowest position in history the last 200 years.

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

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

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

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

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

Salinity. Salinity values ​​are determined by factors such as river flow, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts of the Northern Caspian and between the Northern and Middle Caspian, bottom topography, which determines the location of waters with different salinities, mainly along isobaths, evaporation, providing a deficit of fresh water and an influx of saltier water. These factors collectively influence seasonal differences in salinity.
The Northern Caspian Sea can be considered as a reservoir of constant mixing of river and Caspian waters. The most active mixing occurs in the western part, where both river and Central Caspian waters directly flow. Horizontal salinity gradients can reach 1‰ per 1 km.

The eastern part of the Northern Caspian Sea is characterized by a more uniform salinity field, since most of the river and sea (Middle Caspian) waters enter this area of ​​the sea in a transformed form.

Based on the values ​​of horizontal salinity gradients, it is possible to distinguish in the western part of the Northern Caspian the river-sea contact zone with water salinity from 2 to 10‰, in the eastern part from 2 to 6‰.

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea ​​waters, the determining role is played by runoff. The strengthening of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated waters coming from the seashore in summer is 10–15°C higher than the bottom waters.
In the deep-sea depressions of the Middle and Southern Caspian Sea, fluctuations in salinity in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of ​​the Absheron threshold, where it is 1.6‰ in the surface layer and 2.1‰ at a 5 m horizon.

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

In addition, in the Southern Caspian Sea, an increase in salinity occurs when salted waters are carried out from bays and gulfs on the eastern shelf under the influence of southeastern winds. Subsequently, these waters are transferred to the Middle Caspian Sea.
In the deep layers of the Middle and Southern Caspian Sea, the salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep-water part of the Southern Caspian, the upper limit of waters with high salinity drops to 250 m. Obviously, in these parts of the sea vertical mixing water is difficult.

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

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

Ice formation. The Northern Caspian Sea is covered with ice every year in November, the area of ​​the frozen part of the water area depends on the severity of the winter: in severe winters the entire Northern Caspian Sea is covered with ice, in mild winters the ice remains within 2–3 meter isobath. The appearance of ice in the middle and southern parts of the sea occurs in December-January. On the eastern coast the ice is of local origin, on the western coast it is most often brought from the northern part of the sea. In severe winters, shallow bays freeze off the eastern coast of the middle part of the sea, shores and fast ice form off the coast, and on the western coast, drifting ice spreads to the Absheron Peninsula in abnormally cold winters. The disappearance of ice cover is observed in the second half of February–March.

Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of patterns. The central part of the waters of the Northern Caspian Sea is characterized by a fairly uniform distribution of oxygen. Increased oxygen content is found in the areas near the mouth of the Volga River, and decreased oxygen content in the southwestern part of the Northern Caspian Sea. In the Middle and Southern Caspian highest concentrations oxygen are confined to coastal shallow areas and pre-estuary coastal areas of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.). In the deep-water areas of the Caspian Sea, the main pattern remains the same throughout all seasons - a decrease in oxygen concentration with depth. Thanks to autumn-winter cooling, the density of the North Caspian Sea waters increases to a value at which it becomes possible for North Caspian waters with a high oxygen content to flow along the continental slope to significant depths of the Caspian Sea. The seasonal distribution of oxygen is mainly associated with the annual variation of water temperature and the seasonal relationship between production and destruction processes occurring in the sea. In the spring, the production of oxygen during photosynthesis very significantly covers the decrease in oxygen caused by a decrease in its solubility with an increase in water temperature in the spring. In the areas of the coastal mouths of rivers feeding the Caspian Sea, in the spring there is a sharp increase in the relative oxygen content, which in turn is an integral indicator of the intensification of the photosynthesis process and characterizes the degree of productivity of the mixing zones of sea and river waters. In summer, due to the significant warming of water masses and the activation of photosynthesis processes, the leading factors in the formation of the oxygen regime are photosynthetic processes in surface waters, and biochemical oxygen consumption by bottom sediments in bottom waters. Thanks to high temperature water, stratification of the water column, a large influx of organic matter and its intense oxidation, oxygen is quickly consumed with minimal entry into the lower layers of the sea, as a result of which an oxygen deficiency zone is formed in the Northern Caspian Sea. Intensive photosynthesis in open waters The deep-sea regions of the Middle and Southern Caspian Sea cover the upper 25-meter layer, where oxygen saturation is more than 120%. In autumn, in the well-aerated shallow areas of the Northern, Middle and Southern Caspian Sea, the formation of oxygen fields is determined by the processes of water cooling and the less active, but still ongoing process of photosynthesis. The oxygen content is increasing. The spatial distribution of nutrients in the Caspian Sea reveals the following patterns:

– increased concentrations of nutrients characterize the areas of pre-estuarine coastal rivers that feed the sea and shallow areas of the sea that are subject to active anthropogenic influence(Baku Bay, Turkmenbashi Bay, water areas adjacent to Makhachkala, Fort Shevchenko, etc.);
– The Northern Caspian, which is a vast mixing zone of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
– in the Middle Caspian Sea, the cyclonic nature of the circulation contributes to the rise of deep waters with a high content of nutrients into the overlying layers of the sea;
– in the deep-water regions of the Middle and Southern Caspian Sea, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.

On the dynamics of concentrations nutrients During the year, the Caspian Sea is influenced by such factors as seasonal fluctuations in nutrient runoff into the sea, the seasonal ratio of production-destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter time in the Northern Caspian, processes of winter vertical circulation in deep-water areas of the sea.
In winter, a significant area of ​​the Northern Caspian Sea is covered with ice, but biochemical processes actively develop in subglacial water and in ice. The ice of the Northern Caspian Sea, being a kind of accumulator of nutrients, transforms these substances entering the sea with river runoff and from the atmosphere.

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

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

In the spring season, in the area of ​​water exchange between the Northern and Middle Caspian Seas in the subsurface layer, with a maximum oxygen content, the phosphate content is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.
In the Southern Caspian, the distribution of nutrients in spring is basically similar to their distribution in the Middle Caspian.

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

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

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

From the territory of Russia, about 55 thousand tons of petroleum products enter the Northern Caspian annually, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the runoff of the Terek and Sulak rivers.
Thickening of the film on the water surface to 0.01 mm disrupts gas exchange processes and threatens the death of hydrobiota. The concentration of petroleum products is toxic to fish at 0.01 mg/l and to phytoplankton at 0.1 mg/l.

The development of oil and gas resources on the bottom of the Caspian Sea, the forecast reserves of which are estimated at 12–15 billion tons of standard fuel, will become the main factor in the anthropogenic load on the sea ecosystem in the coming decades.

Caspian autochthonous fauna. The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, mollusks, etc.

Arctic species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire Caspian fauna (mysids, sea cockroach, whitefish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna are crustaceans (71.4%), which easily tolerate desalination and live at great depths of the Middle and Southern Caspian Sea (from 200 to 700 m), since the lowest water temperatures are maintained here throughout the year (4.9– 5.9°C).

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

Freshwater fauna(228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, carp, and also rotifers).

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

The Caspian Sea produces more than 80% of the world's sturgeon catches, the bulk of which occur in the Northern Caspian Sea.
To increase sturgeon catches, which sharply decreased during the years of falling sea levels, a set of measures is being implemented. Among them are a complete ban on sturgeon fishing in the sea and its regulation in rivers, and an increase in the scale of sturgeon factory farming.

Today in Astrakhan the program for celebrating Caspian Sea Day began. Such holidays are celebrated in five Caspian states. Although the Caspian Sea requires in modern conditions not so much festive events, but respect from all who inhabit its shores and exploit its wealth.

“Caspian News”, of course, cannot stand aside, because the attitude towards the Caspian Sea is inherent in the very name and ideology of our portal. Our story about a unique reservoir is a kind of offering to the “hero of the occasion.”

The uniqueness of the Caspian Sea lies, first of all, in the fact that it is not a sea, but a real endorheic lake. The sea must have access to the World Ocean, which the Caspian does not have; on the other hand, this salty lake has all the signs of the sea, from ebbs and flows to real storms, about which sailors say: “No ocean storms are scary for someone who has survived a storm in the Caspian.” " And the oceanic bottom topography is convincing evidence that initially the Caspian Sea, together with the Black and Azov Seas, belonged to a single ancient body of water, that is, it was part of the World Ocean.

Where the Caspian Lake is now located, several tens of thousands of years ago a depression was formed in earth's crust. Today it is filled with the waters of the Caspian Sea. At the end of the 20th century, the water level in the Caspian Sea was 28 meters below the level of the World Ocean. About six thousand years ago, the waters of the Caspian Sea gained independence, parting with the World Ocean. Another feature that distinguishes the Caspian from the sea is that the salinity of the water in it is almost three times lower than the salinity of the sea. This is because the rivers carry their fresh water to the Caspian Sea. The Volga accounts for the largest contribution: it gives almost 80% of all water to the sea-lake. And it also connects the Caspian Sea with the World Ocean through a system of canals. That's why this lake is still considered a sea!

In terms of its area and volume of water, the Caspian Sea-lake has no equal on Earth. The volume of water in the Caspian Sea accounts for 44% of the reserve of all lake waters on the planet! If we talk about the depth of reservoirs, their area and volume of water, the lake can compete with the Yellow, Baltic and Black Seas and surpasses the Aegean and Adriatic Seas in these same parameters.

Not every sea can boast that during its history it has had as many names as the Caspian: as many as seventy! Every traveler, every expedition to the Caspian Sea and the ancient peoples inhabiting its coast gave it their names. The most famous names are: Djurdzhansky, Khvalynsky, Shirvansky, Derbentsky, Saraysky and finally, Khazar. In Azerbaijan and Iran, the Caspian Sea is still called the Khazar Sea. A modern name The sea got its name from the tribes of Caspian horse breeders, who for a very long time inhabited the eastern parts of the Caucasus and the steppes of the Caspian territories.

The Caspian Sea is the hero of many legends and traditions in the epic of all peoples living on its shores. Legends, as a rule, tell about the love of a mighty and handsome Caspian hero for one of the beauties named Volga, Kura or Amu Darya - the choice is huge, since about 130 large and small rivers flow into the sea, nine of which have a mouth in the form deltas. Everyone's fantasy on the theme of love is approximately the same.

The sea area is divided into three regions: Northern, Middle and Southern Caspian. The Northern Caspian is shallow. The greatest depth of the Middle Caspian in the area of ​​the Derbent depression is about 788 m. Beyond the Absheron threshold the South Caspian begins, this is where the sea is deepest: about 1025 m. For clarity, imagine three Eiffel towers stacked on top of each other.

There are many secrets and mysteries associated with the Caspian Sea. In 1939, archaeological divers found a flooded ancient guest house (caravanserai) in Baku Bay. Many inscriptions have been preserved on the walls, indicating that the building was erected in 1234-1235. Perhaps these are the remains of the ancient city of Sabail. Ancient quarries have been discovered nearby in the sea. And in 1940, during the construction of a dam on the Absheron Peninsula, an ancient cemetery was discovered at the bottom of the sea. The burials date back to the 1st century BC. It can be assumed that the level of the Caspian Sea in those days was about four meters lower than today.

It is no coincidence that the inscription on geographical map, compiled in 1320, says: “The sea rises every year to one hand, and many good cities are already flooded”

Instrumental measurements of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out since 1837. The highest water level was recorded in 1882 (−25.2 m), the lowest in 1977 (−29.0 m), since 1978 the water level has risen and in 1995 reached −26.7 m, since 1996 year began to decline again, and since 2001 - to rise again and reached a level of −26.3 m. The reasons for this “behavior” of the Caspian Sea are climate change, as well as geological and anthropogenic factors.

The Caspian seal remains another mystery of the unique sea-lake: scientists cannot answer the question of where the animal of northern latitudes came from in the Caspian Sea. In total, 1809 species of different groups of animals live in the Caspian Sea. The Caspian Sea is also famous for its valuable fish species, in particular sturgeon. Their reserves account for up to 80% of the world's resources. The most valuable caviar is not black, as many are accustomed to believe, but white. Albino Beluga caviar ranges in color from light gray to white. The lighter, the more expensive: the cost of 100 grams is $2,000. This fish is caught in the Caspian Sea off the coast of Iran.

Many oil and gas fields are being developed in the Caspian Sea. The first oil well was drilled on the Absheron Peninsula near Baku back in 1820. In 1949, they began to extract oil from the bottom of the Caspian Sea for the first time. Salt, limestone, stone, sand and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.

The Caspian Sea washes the shores of five countries: Kazakhstan, Azerbaijan, Turkmenistan, Iran and Russia. Caspian Day has been celebrated in every country for several years now, reminding that the Caspian Sea is not just a waterer and breadwinner for the peoples inhabiting its shores, but a very fragile ecosystem.

By the way, in 1978, World Maritime Day appeared on the calendar of world events, which refers to the international UN days, designed to draw humanity’s attention to the problems of the hydraulic system. There is also an International Black Sea Day: in 1996, representatives of Russia, Ukraine, Bulgaria, Romania, Turkey and Georgia signed a strategic action plan to save the Black Sea. In this regard, the Day of the Caspian Sea is also, rather, not a holiday, but a warning, a warning to people about how everything is interconnected in this world and how it is possible, by mercilessly exploiting, to lose what is dear to everyone.

Marina Parenskaya