Is the Caspian Sea fresh? Temperature and salinity

This is how the Mediterranean Sea was formed, which then included the current Azov, Black and Caspian Sea... In place of the modern Caspian Sea, 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 at the place of formation Caucasus mountains, The Caspian Sea was finally cut off from the ocean, and in its place a closed closed body of water was formed, which today is considered the largest inland sea on the planet. However, some scientists call this sea a giant lake.
The peculiarity of the Caspian Sea is the constant fluctuation of the salinity level of its water. Even in different regions of this sea, the water has different salinity. This was the reason that the animal classes of fish and crustaceans predominate in the Caspian Sea, which more easily tolerate fluctuations in water salinity.

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

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

The first group of animals includes the descendants of ancient organisms that inhabited Tethys about 70 million years ago. These animals include Caspian gobies (golovach, Knipovich, Berga, bubyr, pugolovka, Baer) and herring (Kessler, Brazhnikovskaya, Volga, puzanok, etc.), some mollusks and most crustaceans (long-sex crayfish, crustacean ortemia, etc.). Some fish, mainly herring fish, periodically go out into the rivers flowing into the Caspian for spawning, many never leave the sea. Gobies prefer to live in coastal waters and are often found at river mouths.
The second group of animals of the Caspian Sea is represented by Arctic species. penetrated into the Caspian from the north in the postglacial period. These are such animals as the Caspian seal (Caspian seal), fish - Caspian trout, white fish, nelma. From crustaceans, this group is represented by the mysida crustaceans, similar to small shrimps, tiny sea cockroaches and some others.
The third group of animals inhabiting the Caspian includes the species that independently or with the help of humans migrated here from Mediterranean Sea... These are mollusks mitisaster and abra, crustaceans - amphipods, shrimps, Black Sea and Atlantic crabs and some fish species: singil (ostronos), needlefish and Black Sea kalkan (flounder).

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

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

I was resting somehow in the camp... It's no secret that almost every day contests are held there to entertain children and young people. So that's it. Was we have quiz. Question: "Which lake is the largest?" One guy, about fifteen years old, raised his hand first and answered: "Baikal". The strangest thing was that the answer was counted as correct! How so? Isn't the Caspian Sea the most big lake? Now I will explain to you.

How to tell the sea from the lake

I will list several signs by which a body of water is defined as a sea.

1. Rivers can flow into the sea.

2. The Outer Sea has direct access to the ocean.

3. If the sea is internal, then it is connected by straits with other seas or directly with the ocean.

Is the Caspian Sea suitable for the parameters of the sea

Need to check, does the Caspian Sea have signs of the sea. Into it really rivers flow, but they flow into many bodies of water: seas, lakes, oceans, and other rivers. The Caspian Sea is surrounded from all sides by land... Is it really inland sea? Then it must connect with the Black or Azov seas any strait. The strait too No... Exactly due to the lack of access to the World Ocean, the Caspian Sea is considered a lake.

"But why was it then called the sea, if it is a lake?"- you ask. Answer very simple: due to his large size and salinity... Indeed, The Caspian Sea is several times larger than the Azov Sea and is almost the same in size with the Baltic.

Fine! The problem with the quiz has been resolved. Judge for the soap !!!

Well then, i told, that the Caspian Sea in fact - Lake... Now I want to you provide small compilation interesting facts about this lake.

1. The Caspian Sea is below sea level (-28 m), which once again proves that this is a lake.

2. BC near the lake lived nomadic Caspian tribes,in honor of which he was nicknamed the Caspian.

3. This the deepest enclosed body of water on the planet.

4. Many believe that the name of the group "Caspian Cargo" is related to the Caspian Sea... In some ways they are right ( No). Actually the expression "Caspian cargo" can mean any illegal cargo.

5.Caspian Sea OK suitable for tourism... Under the USSR, a large number of sanatoriums were built here. Today the same here you can see many hotels, water parks and beaches.

There are still disputes over the status of the Caspian Sea. The fact is that, despite its common name, it is still the world's largest closed-drainage lake. It was named the sea because of the features that the structure of the bottom has. It is formed by the oceanic crust. In addition, the water in the Caspian is salty. As in the sea, storms and strong winds, raising high waves, are often observed here.

Geography

The Caspian Sea is located at the junction of Asia and Europe. In its shape, it resembles one of the letters 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 North and Middle, as well as the South 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, which stretches along the Caspian for 955 km, washes its shores in the southwest.
5. Iran. The map of the Caspian states indicates that this country is located at southern shores closed lake. Moreover, the length of its sea borders is 724 km.

Is the Caspian Sea?

Until now, the dispute about what to call this unique reservoir has not been resolved. And it is important to answer this question. The point is that all the countries on the Caspian Sea have their own interests in this region. However, the question of how to divide this huge reservoir, the governments of five states have not been able to resolve for a long time. The main controversy revolved around the name. Is the Caspian a sea or a lake after all? Moreover, the answer to this question is not of 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, the 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 the coastal states are assigned a twelve-mile water zone along it. In addition, the country is given the right to an economic sea territory. It is located two hundred miles away. The coastal state also has rights to, however, even the widest part of the Caspian is narrower than the distance stipulated in the international document. In this case, the median 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 should be divided fairly. In this case, all countries will get twenty percent of the sea area. The position of official Tehran is understandable. With such a solution to the issue, the state will control a larger area than when dividing the sea along the middle line.

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

Is the Caspian a lake?

The adherents of this point of view proceed from the fact that the reservoir, located at the junction of Asia and Europe, is closed. In this case, it is impossible to apply the document on the norms of international maritime law to it. The supporters of this theory are convinced that they are right, referring to the fact that the Caspian 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 borders of the states according to what international norms should be determined on its water expanses? Unfortunately, such documents have not yet been developed. The fact is that the issues of the international lake were not discussed anywhere and by anyone.

Is the Caspian a unique body of water?

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

Solving security problems

The Caspian states are doing everything possible to eliminate all existing differences. And in this matter, positive shifts 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 cooperation in the field of security. In this document, the countries agreed on joint activities to eliminate terrorism, drug trafficking, smuggling, poaching, money laundering, etc. in the region.

Environmental protection

Particular attention is paid to solving environmental issues. The territory on which the Caspian states and Eurasia are located is a region under the threat of industrial pollution. Kazakhstan, Turkmenistan and Azerbaijan dump waste from exploration and production of energy resources into the waters of the Caspian Sea. Moreover, it is in these countries that a large number of abandoned oil wells are located, which are not operated due to their unprofitableness, but nevertheless continue to have an adverse effect 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. This is due to the economic activity unfolding in the Volga region.

The countries on the Caspian Sea have made some progress in solving environmental problems. So, since 12.08.2007, the framework convection has been in force in the region, which sets itself the goal of protecting the Caspian Sea. This document developed provisions on the protection of biological resources and regulation of anthropogenic factors affecting the aquatic environment. According to this convection, the parties must interact when taking measures to improve the environmental situation in the Caspian.

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

• Protocol on Cooperation, Response and Regional Preparedness in Case of Occurrences of Oil Pollution.
• Protocol Relating to the Protection of a Region Against Pollution from Land-Based Sources.

Gas pipeline construction development

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

First summit

The countries on the Caspian Sea are constantly looking for ways to solve the problems that have matured in this Eurasian region. For this, special meetings of their representatives are organized. Thus, the first summit of the heads of the Caspian states took place in April 2002. Ashgabat was its venue. However, the results of this meeting did not justify hopes. The summit was considered unsuccessful because of 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 water areas should correspond to the length that the state's coastline has.

The unsuccessful holding of the summit also provoked 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 come to a consensus on any of the issues raised. However, at the same time, an agreement was concluded to hold a second summit. It was supposed to take place in 2003 in Baku.

Second Caspian Summit

Despite the existing agreements, the scheduled meeting was postponed every year. The heads of the Caspian states gathered at the second summit only on October 16, 2007. Tehran was the venue for the summit. The meeting discussed topical issues related to the definition of the legal status of a unique reservoir, which is the Caspian Sea. The borders of the states within the framework of the section of the water area were preliminarily stipulated during the development of the draft new convention. The issues of security, ecology, economy 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 on expanding cooperation on 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, the proliferation of weapons, etc.

Fourth summit

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

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

The Caspian Sea is the largest closed lake on the planet. This body of water is called the sea for its huge size, brackish water and a regime similar to the sea. The level of the Caspian Sea-Lake is 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 depths are 208 and 1025 m, respectively.

The Caspian Sea stretches 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 shores - in oil and gas. The Caspian Sea has been studied quite well, but many mysteries remain in its regime. The most characteristic feature of the reservoir is the instability of the level with sharp drops and climbs. The last rise in the level of the Caspian took place before our eyes from 1978 to 1995. It gave rise to a lot of rumors and speculation. Numerous publications appeared in the press, which spoke of catastrophic floods and an environmental disaster. It was often written that the rise in the level of the Caspian led to the flooding of almost the entire delta of the Volga. What is true in the statements made? What is the reason for this behavior of the Caspian Sea?

WHAT HAPPENED TO CASPIUS IN THE XX CENTURY

Systematic observations over 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 of marks from - 26 to - 25.5 abs. m and had some downward trend. This trend continued in 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 1995 by 2.35 m, reached the level of 26.66 abs. m. In the next four years, the average sea level dropped 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 decline in sea level in 1930-1970 led to the shallowing of coastal waters, the extension of the coastline towards the sea, and the formation of wide beaches. The latter was, perhaps, the only positive consequence of the drop in the level. There were much more negative consequences. With a decrease in the level, the area of ​​fodder lands for fish stocks in the northern Caspian decreased. The shallow estuary seaside of the Volga began to quickly overgrow with aquatic vegetation, which worsened the conditions for the passage of fish to spawn in the Volga. Fish catches, especially of valuable species: 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 coastal areas have already adjusted to the low level.

Many sectors of the economy began to suffer damage. In the zone of flooding and flooding were significant territories, especially in the northern (flat) part of Dagestan, in Kalmykia and Astrakhan region... The rise in water level affected the cities of Derbent, Kaspiysk, Makhachkala, Sulak, Caspian (Lagan) and dozens of other smaller settlements. 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. The abrasion processes in the coastal zone and the influence of seawater surges have intensified. V last years The flora and fauna of the seaside and coastal zone of the Volga delta suffered significant damage.

In connection with the increase in depths in the shallow waters of the Northern Caspian and the reduction of 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 improved somewhat. However, the prevalence of negative consequences from the rising sea level made us talk about an environmental disaster. The development of measures to protect national economic facilities and settlements from the advancing sea began.

HOW UNUSUALLY IS THE CASPIAN'S MODERN BEHAVIOR?

Studies of 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, but there is archaeological, cartographic and other evidence for the historical time and the results of paleogeographic studies covering a longer period.

It is proved that during the Pleistocene (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 in the history of the Caspian Sea, four stages are distinguished: Baku, Khazar, Khvalynsk and Novo-Caspian (Fig. 3). Each stage included several transgressions and regressions. The Baku transgression took place 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 of 10 abs. m) and the Late Khazar (100-200 thousand years ago, the highest level -15 abs. m). The Khvalynsky stage in the history of the Caspian included two transgressions: the largest during the Pleistocene, the Early Khvalynian (40-70 thousand years ago, the maximum level of 47 absolute m, which is 74 m higher than the present) and the Late Khvalynian (10-20 thousand years ago, the rise level up to 0 abs. m). These transgressions were separated by a deep Enotai 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 typical of the Subatlantic Holocene epoch (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 decrease in the level to –50 abs. M), five stages of the Novo-Caspian transgression were noted, separated by small regressions (Fig. 4). Following the 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 elapsed after the Derbent regression, the mean sea level changed in an even narrower range - from –30 to –25 abs. m. This range of changes in the level is called the risk zone.

Thus, the level of the Caspian Sea 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, it is not unusual for the Caspian Sea to rise and fall.

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

Rumors that the rise in sea level caused floods throughout the Volga delta were not confirmed. Moreover, it turned out that the rise in water levels even in the lower part of the delta is inadequate to the magnitude of the rise in sea level. The increase in the water level in the lower part of the delta did not exceed 0.2-0.3 m during the low-water period, and almost did not manifest itself at all during the flood. At the maximum level of the Caspian in 1995, the backwater from the sea side spread along the deepest branch of the Bakhtemir delta by no more than 90 km, and along other branches by no more than 30 km. Therefore, only islands on the seashore and a narrow coastal strip of the delta were flooded. Inundations in the upper and middle parts of the delta were associated with high floods in 1991 and 1995 (which is normal for the Volga delta) and with the unsatisfactory condition of the protective dams. The reason for the weak influence of sea level rise on the Volga delta regime is the presence of a huge shallow seashore zone, which dampens the effect 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, the sea level was higher than at the present time, and this was in no way perceived as an ecological disaster. And before the level was even higher. Meanwhile, Astrakhan has been known since the middle of the XIII century, here in the XIII - the middle of the XVI century the capital of the Golden Horde, Saray-Batu, was located. These and many others settlements on the Caspian coast did not suffer from a high level, as they were located on elevated places and at abnormal flood levels or surges, people temporarily moved from low places to higher ones.

Why are the consequences of a rise in sea level even at lower levels now perceived as a catastrophe? The reason for the enormous damage to the national economy is not a rise in the level, but the thoughtless and short-sighted development of a strip of land within the aforementioned risk zone, freed (as it turned out, temporarily!) From 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, naturally, 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 OF THE CASPIAN LEVEL VIBRATIONS

Considering the question of the causes of fluctuations in the level of the Caspian, it is necessary to pay attention to the opposition 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, the processes of two groups are attributed to the reasons for the change in the level of the Caspian. The processes of the first group, according to geologists, lead to a change in the volume of the Caspian depression and, as a consequence, to changes in sea level. These processes include vertical and horizontal tectonic movements of the earth's crust, the accumulation of bottom sediments, and seismic events. The second group includes processes that, as geologists believe, affect the underground runoff in the sea, either increasing it or decreasing it. Such processes are called periodic squeezing out or absorption of waters that saturate bottom sediments under the influence of changing tectonic stresses (changes in compression and extension periods), as well as technogenic destabilization of the subsoil 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 depression and groundwater runoff. However, at present, the quantitative relationship of geological factors with fluctuations in the level of the Caspian 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 basin of the Caspian Sea is located within a geologically heterogeneous territory, which results in the periodic rather than linear nature of 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 also evidenced by the fact that coastlines New Caspian transgressions in all parts of the Caspian coast (with the exception of certain areas within the Apsheron archipelago) are at the same level.

There is no reason to believe that the reason for the fluctuations in the level of the Caspian is the change in the capacity of its basin due to the accumulation of precipitation. The rate of filling the basin with bottom sediments, among which the main role is played by the outflow of rivers, is estimated, according to modern data, at 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 decay at close distances from it, cannot significantly affect the volume of the Caspian basin.

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

The main proof 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 Sea level.

CHANGE IN THE CASPIAN WATER BALANCE COMPONENTS AS THE MAIN CAUSE OF ITS LEVEL VIBRATIONS

For the first time, fluctuations in the level of the Caspian were explained by changes in climatic conditions (more specifically, river runoff, evaporation and atmospheric precipitation on the sea surface) 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 proven 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 input (river and groundwater runoff, atmospheric precipitation to the sea surface) and consumption (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 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 runoff of the rivers Volga, Ural, Terek, Sulak, Samur, Kura and visible or effective evaporation, the difference between evaporation and precipitation on the sea surface. The analysis of the components of the water balance revealed that the greatest contribution (up to 72% of the variance) to the level variability comes from the inflow of river waters, and more specifically, the zone of flow formation in the Volga basin. As for the reasons for the change in the Volga runoff itself, they are associated, as many researchers believe, with the variability of atmospheric precipitation (mainly winter) in the river basin. And the precipitation regime, in turn, is determined by the circulation of the atmosphere. It has long been proven that the increase in precipitation in the Volga basin is facilitated by the latitudinal type of atmospheric circulation, while the decrease is facilitated by the meridional type.

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 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 visible evaporation.

Bearing in mind that river runoff is one of the main factors affecting the water balance and, as a consequence, the level of the Caspian Sea (and the Volga runoff gives 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 relationship between sea level and the runoff of the Volga alone, which is measured most accurately. Direct correlation of these values ​​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 every year, but the ordinates of the differential integral runoff curve are taken, that is, the sequential sum of the normalized deviations of the annual runoff values ​​from the mean long-term value (norm). Even a visual comparison of the course of the average annual levels of the Caspian Sea and the differential integral curve of the Volga runoff (see Fig. 2) reveals their similarity.

Over the entire 98-year period of observations of the Volga runoff (Verkhnee Lebyazhye village at the top of the delta) and sea level (Makhachkala), the correlation coefficient of the relationship between sea level and ordinates of the differential integral runoff curve was 0.73. If we discard the years with small level changes (1900-1928), then the correlation coefficient rises to 0.85. If for the 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 above calculation results fully confirm the conclusion that during periods of a sharp decrease or increase in sea level, the levels themselves are closely related to the runoff (more precisely, with 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, a reduction in river runoff due to its irreversible losses for filling reservoirs, evaporation from the surface of artificial reservoirs, and water intake for irrigation. It is believed that since the 1940s, irreversible water consumption has steadily increased, 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 natural. According to V.N. Malinin, by the end of the 80s, the difference between the actual sea level and the restored (natural) level reached almost 1.5 m.At the same time, the total irretrievable 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 not for the withdrawal of river flow, the rise in sea level would not have begun in the late 70s, but in the late 50s.

The increase in water consumption in the Caspian basin by 2000 was forecasted first up to 65 km3 / year, and then up to 55 km3 / year (36 of them fell on the Volga). Such an increase in irrecoverable losses of river flow should have reduced 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, the estimates of water intake and evaporation losses from the surface of reservoirs in the Volga basin found in the literature seem to be significantly overestimated. Secondly, forecasts of water consumption growth turned out to be erroneous. The forecasts laid down the rates of development of water-consuming sectors of the economy (especially irrigation), which not only turned out to be unrealistic, but were also replaced by 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 now it has decreased to 30-35 km3 / year (in the Volga basin to 24 km3 / year). Therefore, the "anthropogenic" difference between natural and actual sea level is currently not as great as predicted.

ON POSSIBLE VIBRATIONS OF THE CASPIAN LEVEL IN THE FUTURE

The author does not aim to analyze 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 Sea can be made as follows. Although the predictions were based on completely different approaches (both deterministic and probabilistic), there was not a single reliable prediction. 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 sea level declined in the 1930s and 1970s, most researchers predicted a further drop. In the last two decades, when the sea level began to rise, most forecasts predicted an almost linear and even accelerating growth of the level to - 25 and even - 20 abs. m and higher at the beginning of the XXI century. At the same time, three circumstances were not taken into account. First, the periodic nature of fluctuations in the level of all closed water bodies. The instability of the Caspian Sea 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 litter bays on the northeastern coast of the Caspian - Dead Kultuk and Kaidak, dried out at a low level, will begin, as well as low-lying areas in other parts of the coast. This would lead to an increase in the area of ​​shallow waters and, as a consequence, to an increase in evaporation (up to 10 km3 / year). At a higher sea level, the outflow of water to Kara-Bogaz-Gol will increase. All this should stabilize or at least slow down the growth of the level. Third, fluctuations in the level under the conditions of the modern climatic epoch (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 - 26-26.5 abs. m.

A 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 the sea level is unlikely to exceed the mark - 26 abs. m seems to be justified.

In the 20th century, the level of the Caspian Sea varied within 3.5 m, first dropping 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 input (river runoff, precipitation on the sea surface) and consumption (evaporation from the surface of the 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, striving to achieve an equilibrium state, but never reaches it. Ultimately, the tendency of changes in the level of the Caspian Sea in the given time depends on the ratio of precipitation minus evaporation in the catchment (in the basins of the rivers feeding it) and evaporation minus precipitation over the reservoir itself. The recent 2.3 m rise in the Caspian Sea level is not really unusual. 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 disaster for the economy of the coastal zone only due to the unreasonable development of this risk zone by man.

Vadim Nikolaevich Mikhailov, Doctor of Geography, 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 Management Sciences. Research interests - hydrology and water resources, interaction of rivers and seas, delta and estuary, hydroecology. Author and co-author of about 250 scientific works, including 11 monographs, two textbooks, four scientific and methodological manuals.

, Kura

Caspian Sea- the largest closed body of water on Earth, which can be classified as the largest closed lake, or as a full-fledged sea, due to its size, as well as due to the fact that its bed is composed of oceanic crust. Located at the junction of Europe and Asia. The water in the Caspian is brackish, - from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data was 27.16 m below sea level. The area of ​​the Caspian Sea is currently about 371,000 km², the maximum depth is 1025 m.

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Etymology

Geographical position

The Caspian Sea is located at the junction of Europe and Asia. The length of the sea from north to south is about 1200 kilometers (36 ° 34 "-47 ° 13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46 ° -56 ° E etc.).

According to physical and geographical conditions, the Caspian Sea is conditionally divided into three parts - the North Caspian (25% of the sea area), the Middle Caspian (36%) and the South Caspian (39%). The conditional border between the North and Middle Caspian runs along the line of Chechen Island - Cape Tyub-Karagan, between the Middle and South Caspian - along the line of Chilov Island - Cape Gan-Gulu.

Coast

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

Peninsula

• Absheron Peninsula, located on west coast Caspian Sea on the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory are the cities of Baku and Sumgait
• Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory there is the city of Aktau

Islands

There are about 50 large and medium-sized islands in the Caspian Sea with a total area of ​​about 350 square kilometers.

The largest islands:

Gulfs

Large bays:

Kara-Bogaz-Gol

The east coast is salt Lake Kara-Bogaz-Gol, which until 1980 was a bay-lagoon of the Caspian Sea, connected to it by a narrow strait. In 1980, a dam was built, separating Kara-Bogaz-Gol from the Caspian Sea, in 1984 a culvert was built, after which the level of Kara-Bogaz-Gol dropped several meters. In 1992, the strait was restored, along it the water leaves the Caspian Sea to Kara-Bogaz-Gol and evaporates there. Every year from the Caspian Sea, Kara-Bogaz-Gol receives 8-10 cubic kilometers of water (according to other sources - 25 cubic kilometers) and about 15 million tons of salt.

Rivers flowing into the Caspian Sea

130 rivers flow into the Caspian Sea, 9 of which have delta-shaped estuaries. Large rivers flowing into the Caspian Sea are Volga, Terek, Sulak, Samur (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Atrek (Turkmenistan), Sefidrud (Iran). Largest river The Volga, which flows into the Caspian Sea, has an average annual runoff of 215-224 cubic kilometers. The Volga, Ural, Terek, Sulak and Emba provide up to 88-90% of the annual runoff into the Caspian Sea.

Basin of the Caspian Sea

Coastal states

According to the Intergovernmental Economic Conference of the Caspian States:

The Caspian Sea washes the shores of five coastal states:

Cities on the coast of the Caspian Sea

On the Russian coast there are cities - Lagan, Makhachkala, Kaspiysk, Izberbash, Dagestanskie Ogni and the most Southern City 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 the fluctuations in the water level. 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 above its surface. 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 according to the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian 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, charovy and others, from flowering plants - zostera and ruppia. In origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into the Caspian Sea by humans deliberately, or on the bottoms of ships.

History

Origin

The Caspian Sea is of oceanic origin - its bed is composed of oceanic crust. 13 million liters. n. the formed Alps separated the Sarmatian Sea from the Mediterranean. 3.4 - 1.8 million liters. n. (Pliocene) the Akchagyl Sea existed, the deposits of which were investigated by N.I. Andrusov. Originally formed on the site of the dried-up Pontic Sea, from which Lake Balakhany remained (on the territory of the southern Caspian Sea). The Akchagyl transgression was replaced by the Domashka regression (a drop of 20 - 40 m from the level of the Akchagyl basin), accompanied by strong desalination of sea waters, which is due to the termination of the supply of sea (oceanic) waters from the outside. After a short Domashkin regression at the beginning of the Quaternary period (Eopleistocene), the Caspian is almost restored in the form of the Absheron Sea, which covers the Caspian and floods the territories of Turkmenistan and the Lower Volga region. At the beginning of the Absheron transgression, the basin turns into a brackish water body. The Absheron Sea exists from 1.7 to 1 million years ago. The beginning of the Pleistocene in the Caspian Sea was marked by a long and deep Türkyan regression (-150 m to -200 m), corresponding to the Matuyama-Brunhes magnetic inversion (0.8 million years ago). The water mass of the Türkyan basin with an area of ​​208 thousand km² was concentrated in the South Caspian and part of the Middle Caspian basins, between which there was a shallow strait in the area of ​​the Apsheron threshold. In the Early Neopleistocene, after the Türkyan regression, there existed an isolated Early Bakinsky basin and a late Bakinsky (level up to 20 m) drainage basin (about 400 ka BP). The Venedian (Mishovdag) regression divided the Baku and Urundzhik (Middle Neopleistocene, up to −15 m) transgressions at the end of the early - beginning of the late Pleistocene (basin area - 336 thousand km²). A large deep Cheleken regression (up to −20 m), corresponding to the optimum of the Likhvin interglacial (350-300 thousand years ago), was noted between the marine Urundzhik and Khazar deposits. In the Middle Neopleistocene, there were basins: the Early Khazar Early (200 thousand years ago), the Early Khazar Middle (level up to 35-40 m), and the Early Khazar Late. In the Late Neopleistocene, there was an isolated Late Khazar basin (level up to −10 m, 100 ka), after which a small Cherniyarsk regression of the second half - the end of the Middle Pleistocene (thermoluminescent dates 122-184 ka) occurred, in in turn, replaced by the Girkan (Gyurgyan) basin.

The deep long-term Atelian regression of the mid-late Pleistocene at the initial stage had a level of −20 - −25 m, at the maximum stage −100 - −120 m, at the third stage - −45 - −50 m. At the maximum, the basin area is reduced to 228 thousand km² ... After atelier regression (−120 - −140 m), approx. 17 thousand liters n. the early Khvalynian transgression began - up to + 50 m (the Manych-Kerch Strait was functioning), which was interrupted by the Elton regression. The Early Khvalynian II basin (level up to 50 m) was replaced at the beginning of the Holocene by a short-term Enotai regression (from −45 to −110 m), coinciding in time with the end of the Preboreal and the beginning of the Boreal. Enotaevskaya regression was replaced by late Khvalynian transgression (0 m). The late Khvalynian transgression was replaced in the Holocene (about 9-7 thousand years ago or 7.2-6.4 thousand years ago) by the Mangyshlak regression (from -50 to -90 m). The Mangyshlak regression was replaced in the first phase of interglacial cooling and humidification (Atlantic period) by the Novocaspian transgression. The Novocaspian basin was brackish water (11-13 ‰), warm water and isolated (level up to −19 m). At least three cycles of transgressive-regressive phases in the development of the Novo-Caspian basin have been recorded. The Dagestan (Gousan) transgression previously belonged to the initial stage of the New Caspian epoch, however, the absence of the leading Novocaspian form in its sediments Cerastoderma glaucum (Cardium edule) provides a basis for its separation into an independent transgression of the Caspian. Izberbash regression, separating the Dagestan and the New Caspian transgressions of the Caspian proper, occurred in the interval between 4.3 and 3.9 thousand years ago. Judging by the structure of the Turali section (Dagestan) and the data of radiocarbon analysis, transgressions were recorded twice - about 1900 and 1700 years ago.

Anthropological and cultural history of the Caspian Sea

Shipping

Shipping is well developed in the Caspian Sea. Ferry services operate on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with Sea of ​​Azov across the Volga, Don and Volga-Don canal.

Fishing and seafood production

Fishing (sturgeon, bream, carp, pike perch, sprat), caviar and seal fishing. More than 90 percent of the world's sturgeon catch is carried out in the Caspian Sea. In addition to industrial production, illegal production of sturgeon and their caviar is flourishing in the Caspian Sea.

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and curative mud in the coastal area creates good conditions for relaxation and treatment. At the same time, in terms of the development of resorts and tourism industry, the Caspian coast is noticeably inferior to the Black Sea coast of the Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coast of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. Azerbaijan is actively developing resort area in the Baku region. At the moment, a world-class resort has been created in Amburan, another modern tourist complex is being built in the area of ​​the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also developing in Nabran, in the north of Azerbaijan. However, high prices, generally low level of service and lack of advertising lead to the fact that there are almost no foreign tourists in the Caspian resorts. The development of the tourism industry in Turkmenistan is hindered by a long-term policy of isolation, in Iran - by Sharia law, which makes it impossible for foreign tourists to spend mass vacations on the Caspian coast of Iran.

Ecological problems

Ecological problems The Caspian Sea is associated with water pollution as a result of oil production and transportation on the continental shelf, the influx of pollutants from the Volga and other rivers flowing into the Caspian Sea, the vital activity of coastal cities, as well as the flooding of certain objects due to the rise in the level of the Caspian Sea. Predatory hunting of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeon and to forced restrictions on their production and export.

Legal status

After the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of the resources of the Caspian shelf - oil and gas, as well as biological resources... For a long time, negotiations were going on between the Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran - on dividing the Caspian by one fifth between all the Caspian states.

With regard to the Caspian, the key is the physical and geographical circumstance that it is a closed inland water body that does not have a natural connection with the World Ocean. Accordingly, the norms and concepts of international maritime law, in particular, the provisions of the 1982 UN Convention on the Law of the Sea, should not be automatically applied to the Caspian Sea. Based on this, in relation to the Caspian it would be inappropriate to apply such concepts as "territorial sea", "exclusive economic zone", "continental shelf", etc.

The current legal regime of the Caspian Sea was established by the Soviet-Iranian treaties of 1921 and 1940. These treaties provide for freedom of navigation throughout the sea, freedom of fishing with the exception of ten-mile national fishing zones and a ban on ships flying the flag of non-Caspian states in its waters.

Negotiations on the legal status of the Caspian are ongoing.

Delimitation of sections of the seabed of the Caspian Sea for the purpose of subsoil use

The Russian Federation signed an agreement with Kazakhstan on delimiting the bottom of the northern part of the Caspian Sea in order to exercise sovereign rights to subsoil use (dated July 6, 1998 and the Protocol to it dated May 13, 2002), an agreement with Azerbaijan on delimiting adjacent sections of the bottom of the northern part of the Caspian Sea (dated September 23, 2002), as well as the trilateral Russian-Azerbaijani-Kazakh agreement on the junction point of the delimitation lines of adjacent sections of the Caspian Sea bottom (dated May 14, 2003), which established geographical coordinates dividing lines limiting the seabed areas within which the parties exercise their sovereign rights in the field of exploration and production of mineral resources.