The Caspian Sea is the world's largest endorheic body of water at a level of 28.5 m below the level of the World Ocean. The Caspian Sea stretches from north to south for almost 1200 km, the average width is 320 km, the length of the coastline is about 7 thousand km. The area of the Caspian Sea as a result of lowering the level decreased from 422 thousand km2 (1929) to 371 thousand km2 (1957). The volume of water is about 76 thousand km3, the average depth is 180 m. The coefficient of indentation of the coast is 3.36. The largest bays: Kizlyar, Komsomolets, Kara-Bogaz-Gol, Krasnovodsk, Mangyshlak.
There are about 50 islands with a total area of 350 km2. The most significant of them: Kulaly, Tyuleniy, Chechen, Zhiloy. More than 130 rivers flow into the Caspian Sea. The Volga, Ural, Emba, Terek rivers (total annual flow 88% of all river runoff into the sea) flows into the northern part of the sea. On its western coast, the Sulak, Samur, Kura and other smaller rivers provide 7% of the total runoff. The remaining 5% of the flow is supplied by the rivers of the Iranian coast.
The relief of the bottom of the Caspian Sea
According to the nature of the underwater relief and the features of the hydrological regime in the Caspian Sea, the North, Middle and South Caspian are distinguished. The Northern Caspian (about 80,000 km2) is a shallow, slightly undulating, accumulative plain with prevailing depths of 4–8 capes. Within the Middle Caspian (138 thousand km2) shelf, continental slope and Derbent depression (maximum depth 788 m). The Apsheron threshold - a chain of banks and islands with depths of 170 m between them - limits the Middle Caspian from the south. The Southern Caspian (1/3 of the area of the sea) is distinguished by a very narrow shelf near the western and southern coasts and a much more extensive shelf near the eastern coast. In the depression of the South Caspian, the deepest sea depth of 1025 m was measured. The bottom of the depression is a flat abyssal plain.Climate in the Caspian Sea
The main oaric centers that determine the atmospheric circulation over the Caspian Sea are: in winter - a spur of the Asian high, and in summer - the crest of the Azores high and the trough of the South Asian depression. Characteristic features of the climate are the predominance of anticyclonic weather conditions, dry winds, and sharp changes in air temperature.In the northern and middle parts of the Caspian Sea, from October to April, the winds of the eastern quarter prevail, and from May to September, the winds of the northwestern rhumbs prevail. In the southern part of the Caspian Sea, the monsoon character of the winds is clearly expressed.
The average long-term air temperature of the warm months (July-August) over the entire sea is 24-26°C. The absolute maximum (up to 44°C) is noted on east coast. On average, 200 mm of precipitation falls over the sea per year, with 90-100 mm on the arid eastern coast and 1700 mm in the subtropical southwestern part of the coast. Evaporation in most of the water area is about 1000 mm/year, and in the eastern part of the South Caspian and in the area of the Apsheron Peninsula up to 1400 mm/year.
Hydrological regime
The currents of the Caspian Sea are formed as a result of the combined effect of the wind regime, river runoff and density differences in individual areas. In the northern part of the Caspian Sea, the waters of the Volga River are divided into two branches. The smaller of them goes along the northern coast to the east, merges with the waters of the Ural River and forms a closed circulation. The main part of the waters of the Volga runoff goes along West Bank South. Somewhat to the north of the Absheron Peninsula, part of the waters of this current separates and, crossing the sea, goes to its eastern shores and flows into the waters moving to the north. Thus, in the Middle Caspian, a water cycle is formed, moving counterclockwise. The bulk of the waters spreading to the south. along west coast, enters the South Caspian and, having reached south coast, turns east, and then along the eastern coast goes north.The speed of the currents is on average about 10–15 cm/s. Frequent recurrence of moderate and strong winds causes a large number of days with significant excitement.
The maximum wave height (11 m) is observed in the area of the Apsheron threshold. The water temperature of the surface layer of the sea in August is about 24-26 ° C in the North and Middle Caspian, up to 29 ° C in the South, 32 ° C in the Krasnovodsk Bay and over 35 ° C in the Kara-Bogaz-Gol Bay. In July-August, upwelling and associated temperature drops to 8-10°C are observed off the eastern shores.
Ice formation in the northern part of the Caspian Sea begins in December, and the ice remains for 2-3 months. In cold winters, drifting ice is carried south to the Absheron Peninsula.
Isolation from the World Ocean, the influx of river waters and the precipitation of salts as a result of intense evaporation in the Kara-Bogaz-Gol Bay determine the originality salt composition waters of the Caspian Sea - a reduced content of chlorides and an increased concentration of carbonates in comparison with the waters of the World Ocean. The Caspian Sea is a brackish water basin, the salinity of which is three times less than the normal ocean.
The average salinity of the waters of the northwestern part of the Caspian Sea is 1-2 ppm, in the region of the northern border of the Middle Caspian 12.7-12.8 ppm, and in the South Caspian 13 ppm, the maximum salinity (13.3 ppm) is observed near the eastern shores. In the Gulf of Kara-Bogaz-Gol, the salinity is 300 ppm; In the Northern and Southern Caspian, due to the reduction in inflow and salinization during ice formation, salinity increases in winter. In the South Caspian at this time, salinity decreases due to a decrease in evaporation. In summer, an increase in river flow causes a decrease in the salinity of waters in the North and Middle Caspian, and increasing evaporation leads to an increase in the salinity of the waters of the South Caspian. Changes in salinity from the surface to the bottom are small. Therefore, seasonal fluctuations in temperature and salinity of water, causing an increase in density, determine the winter vertical circulation of water, which in the Northern Caspian extends to the bottom, and in the Middle Caspian to a depth of 300 m. in winter, the waters of the Middle Caspian through the Apsheron threshold and the sliding of cooled waters of high salinity from the eastern shallow water. Studies have shown that due to the increase in water salinity over the past 25 years, the depth of mixing has increased significantly, the oxygen content has correspondingly increased, and hydrogen sulfide contamination of deep waters has disappeared.
Tidal fluctuations in the level of the Caspian Sea do not exceed 3 cm. about 0.7 m. The range of seasonal level fluctuations is about 30 cm. A characteristic feature of the hydrological regime of the Caspian Sea is sharp interannual fluctuations in the average annual level. The average level from zero of the Baku footstock for a century (1830-1930) was 326 cm. The highest level (363 cm) was observed in 1896. cm. In the last decade, the level of the Caspian Sea has stabilized at low levels with interannual fluctuations of the order of ±20 cm. Fluctuations in the level of the Caspian Sea are associated with climate changes over the entire basin of this sea.
To prevent a further drop in sea level, a system of measures is being developed. There is a project to transfer the waters of the northern rivers Vychegda and Pechora to the Volga river basin, which will increase the flow by about 32 km3. A project was developed (1972) to regulate the flow of Caspian waters into the Kara-Bogaz-Gol Bay.
The Caspian Sea is one of the largest salt water bodies of the Earth, located at the junction of Europe and Asia. Its total area is about 370 thousand square meters. km. The reservoir receives more than 100 water flows. The largest rivers flowing into - Volga, Ural, Emba, Terek, Sulak, Samur, Kura, Atrek, Sefidrud.
The Volga River - the pearl of Russia
The Volga is a river that flows through the territory of the Russian Federation and partially crosses Kazakhstan. Belongs to the largest and long rivers on the ground. The total length of the Volga is more than 3500 km. The river originates in the village of Volgoverkhovye, Tver Region, located on Russian Federation.
It flows into the Caspian Sea, but does not have a direct outlet to the World Ocean, so it is classified as an internal drain. The watercourse receives about 200 tributaries and has more than 150 thousand drains. Today, reservoirs have been built on the river, allowing to regulate the flow, due to which the fluctuations in the water level have been sharply reduced.
The fishery of the river is diverse. Melon growing prevails in the Volga region: the fields are occupied by grain and industrial crops; salt is mined. Oil and gas fields have been discovered in the Ural region. The Volga is the largest river flowing into the Caspian Sea, so it is of great importance for Russia. The main transport facility that allows crossing this stream is the longest one in Russia.
Ural - a river in Eastern Europe
The Ural, like the Volga River, flows on the territory of two states - Kazakhstan and the Russian Federation. Historical name - Yaik. It originates in Bashkortostan at the top of the Uraltau ridge. The Ural River flows into the Caspian Sea. Its basin is the sixth largest in the Russian Federation, and the area is more than 230 square meters. km. An interesting fact: the Ural River, contrary to popular belief, belongs to the inland European river, and only its upper course in Russia belongs to Asia.
The mouth of the stream gradually becomes shallower. At this point, the river splits into several branches. This feature is typical throughout the entire length of the channel. During floods, you can watch the Ural overflow its banks, in principle, like many other Russian rivers flowing into the Caspian Sea. This is especially observed in places with a gently sloping coastline. Flooding occurs at a distance of up to 7 meters from the riverbed.
Emba - the river of Kazakhstan
Emba is a river flowing on the territory of the Republic of Kazakhstan. The name comes from the Turkmen language, literally translated as "the valley of food." The river basin with an area of 40 thousand square meters. km. The river begins its journey in the mountains of Mugodzhary and, flowing along, is lost among the swamps. Asking which rivers flow into the Caspian Sea, we can say that in full-flowing years, the Emba reaches its basin.
Along the coastline of the river, such natural resources like oil and gas. The issue of passing the border between Europe and Asia along the Emba watercourse, as in the case of the river. Ural, an open topic today. The reason for this is a natural factor: the mountains of the Ural Range, which are the main reference point for drawing borders, disappear, forming a homogeneous area.
Terek - mountain water stream
Terek - river North Caucasus. The name literally translates from Turkic as "poplar". The Terek flows out of the glacier of Mount Zilga-Khokh, located in the Trusovsky Gorge of the Caucasus Range. passes through the lands of many states: North Ossetia, Georgia, Stavropol Territory, Kabardino-Balkaria, Dagestan and the Chechen Republic. It flows into the Caspian Sea and the Arkhangelsk Bay. The length of the river is just over 600 km, the basin area is about 43 thousand square meters. km. An interesting fact is that every 60-70 years the flow forms a new transit arm, while the old one loses its strength and disappears.
The Terek, like other rivers flowing into the Caspian Sea, is widely used to meet the economic needs of man: it is used to irrigate the arid territories of the adjacent lowlands. There are also several hydroelectric power plants on the water stream, the total average annual output of which is more than 200 million kWh. In the near future, it is planned to launch additional additional stations.
Sulak - water stream of Dagestan
Sulak is a river that connects the streams of the Avar Koisu and the Andi Koisu. It flows through the territory of Dagestan. It starts in the Main Sulak Canyon and ends its journey in the waters of the Caspian Sea. The main purpose of the river is the water supply of two cities of Dagestan - Makhachkala and Kaspiysk. Also, several hydroelectric power stations are already located on the river, it is planned to launch new ones to increase the generated capacity.
Samur - the pearl of South Dagestan
Samur is the second largest river in Dagestan. Literally, the name from the Indo-Aryan is translated as "an abundance of water." It originates at the foot of Mount Guton; It flows into the waters of the Caspian Sea in two branches - Samur and Small Samur. The total length of the river is just over 200 km.
All rivers flowing into the Caspian Sea are of great importance for the territories through which they flow. Samur is no exception. The main direction of using the river is irrigation of lands and providing residents of nearby cities with drinking water. It was because of this that a hydroelectric complex and a number of the Samur-Divichinsky canal were built.
At the beginning of the 20th century (2010), Russia and Azerbaijan signed an interstate agreement requiring both sides to rationally use the resources of the Samur River. The same agreement included territorial changes between these countries. The border between the two states has been moved to the middle of the hydroelectric complex.
Kura - the largest river of Transcaucasia
Asking the question which rivers flow into the Caspian Sea, I want to describe the flow of the Kuru. It flows on the land of three states at once: Turkey, Georgia, Azerbaijan. The length of the stream is more than 1000 km, the total area of the basin is about 200 thousand square meters. km. Part of the basin is located on the territory of Armenia and Iran. The source of the river is located in the Turkish province of Kars, flows into the waters of the Caspian Sea. The path of the river is thorny, laid among hollows and gorges, for which it got its name, which in translation from the Megrelian language means “to gnaw”, that is, the Kura is a river that “gnaws” itself even among the mountains.
There are many cities on it, such as Borjomi, Tbilisi, Mtskheta and others. It plays an important role in meeting the economic needs of the inhabitants of these cities: hydroelectric power stations are located, and the Mingachevir reservoir created on the river is one of the main fresh water reserves for Azerbaijan. Unfortunately, the ecological state of the stream leaves much to be desired: the level of harmful substances exceeds the permissible limits by several times.
Features of the Atrek River
Atrek is a river located on the territory of Iran and Turkmenistan. It originates in the Turkmen-Kharasan mountains. Due to the active use in economic needs for irrigation of land, the river became shallow. For this reason, it reaches the Caspian Sea only during the flood period.
Sefidrud - the abundant river of the Caspian
Sefidrud is a major river of the Iranian state. It was originally formed by the confluence of two water streams - Kyzyluzen and Shakhrud. Now it flows out of the Shabanau reservoir and flows into the depths of the Caspian Sea. The total length of the river is over 700 km. The creation of a reservoir has become a necessity. It made it possible to minimize the risks of flooding, thereby securing the cities located in the river delta. The waters are used for irrigation of land with a total area of more than 200 thousand hectares of land.
As can be seen from the presented material, the Earth's water resources are in an unsatisfactory state. The rivers flowing into the Caspian Sea are actively used by man to meet his needs. And this has a detrimental effect on their condition: watercourses are depleted and polluted. That is why scientists around the world are sounding the alarm and conducting active propaganda, calling for saving and conserving water on Earth.
Caspian SeaThe Caspian Sea is one of the most amazing enclosed bodies of water on Earth.
Over the centuries, the sea has changed more than 70 names. The modern came from the Caspians - the tribes inhabiting the central and southeastern part of Transcaucasia 2 thousand years BC.
Geography of the Caspian Sea
The Caspian Sea is located at the junction of Europe with Asia and geographic location is divided into the South, North and Middle Caspian.
The middle and northern part of the sea belongs to Russia, the southern part to Iran, the eastern part to Turkmenistan and Kazakhstan, and the southwestern part to Azerbaijan.
For many years, the Caspian states have been dividing the Caspian water area among themselves, and quite sharply at that.
Caspian sea map
Lake or sea?
In fact, the Caspian Sea is the world's largest lake, but has a number of nautical signs.
These include: a large water mass of the reservoir, severe storms with high waves, ebbs and flows.
But the Caspian has no natural connection with the World Ocean, which makes it impossible to call it a sea.
At the same time, thanks to the Volga and artificially created channels, such a connection appeared.
The salinity of the Caspian Sea is 3 times lower than the usual sea level, which does not allow classifying the reservoir as a sea.
There were times when the Caspian Sea was indeed part of the World Ocean.
Several tens of thousands of years ago, the Caspian was connected to the Sea of Azov, and through it to the Black and Mediterranean.
As a result of long-term processes occurring in the earth's crust, formed Caucasian mountains that isolated the reservoir.
Communication between the Caspian and Black Seas for a long time was carried out through the strait (Kumo-Manych depression) and gradually ceased.
Physical quantities
Area, volume, depth
The area, volume and depth of the Caspian Sea are not constant and directly depend on the water level.
On average, the area of \u200b\u200bthe reservoir is 371,000 km², the volume is 78,648 km³ (44% of all world lake water reserves).
Depth of the Caspian Sea in comparison with lakes Baikal and Tanganyika
The average depth of the Caspian is 208 m, the northern part of the sea is considered the shallowest. The maximum depth is 1025 m, noted in the South Caspian depression.
In depth, the Caspian is second only to Baikal and Tanganyika.
The length of the lake from north to south is about 1200 km, from west to east an average of 315 km. The length of the coastline is 6600 km, with islands - about 7 thousand km.
coast
Primarily, the coast of the Caspian Sea is low-lying and smooth.
In the northern part- heavily indented by the river channels of the Urals and the Volga. The swampy local shores are located very low.
Eastern Shores adjacent to semi-desert zones and deserts, covered with limestone deposits.
The most winding coasts are in the west in the region of the Apsheron Peninsula, and in the east - in the area of the Kazakh Gulf and Kara-Bogaz-Gol.
Temperature sea water
The temperature of the Caspian Sea in different time of the year
Average water temperature in winter in the Caspian it fluctuates from 0 °С in the northern part and up to +10 °С in the southern part.
In the waters of Iran, the temperature does not fall below +13 °C.
With the onset of cold weather, the shallow northern part of the lake is covered with ice, which lasts for 2-3 months. The thickness of the ice cover is 25-60 cm, at especially low temperatures it can reach 130 cm. In late autumn and winter, drifting ice floes can be observed in the north.
Summer average temperature the surface of the water in the sea is + 24 °C.
Most of the sea warms up to +25 °C ... +30 °C.
Warm water and beautiful sandy, occasionally shell and pebble beaches create excellent conditions for a full-fledged beach holiday.
In the eastern part of the Caspian Sea near the city of Begdash, during the summer months, abnormally low temperature water.
Nature of the Caspian Sea
Islands, peninsulas, bays, rivers
The Caspian Sea includes about 50 large and medium-sized islands, the total area of which is 350 km².
The largest of them are: Ashur-Ada, Garasu, Gum, Dash and Boyuk-Zira. The largest peninsulas are: Agrakhansky, Absheronsky, Buzachi, Mangyshlak, Miankale and Tyub-Karagan.
Tyuleniy Island in the Caspian Sea, part of the Dagestan Reserve
To the largest bays of the Caspian include: Agrakhan, Kazakh, Kizlyar, Dead Kultuk and Mangyshlak.
In the east is salt Lake Kara-Bogaz-Gol, previously a lagoon connected to the sea by a strait.
In 1980, a dam was built on it, through which water from the Caspian goes to Kara-Bogaz-Gol, where it then evaporates.
130 rivers flow into the Caspian Sea located mainly in its northern part. The largest of them: Volga, Terek, Sulak, Samur and Ural.
The average annual runoff of the Volga is 220 km³. 9 rivers have a delta-shaped mouth.
Flora and fauna
About 450 species of phytoplankton live in the Caspian Sea, including algae, aquatic and flowering plants. Of the 400 species of invertebrates, worms, crustaceans and mollusks predominate. There are a lot of small shrimp in the sea, which is an object of fishing.
More than 120 species of fish live in the Caspian and Delta. Fishing objects are sprat (“Kilkin fleet”), catfish, pike, bream, pike perch, kutum, mullet, vobla, rudd, herring, white fish, pike perch, goby, grass carp, burbot, asp and pike perch. Stocks of sturgeon and salmon are currently depleted, however, the sea is the largest supplier of black caviar in the world.
Fishing in the Caspian Sea is allowed all year round except for the period from late April to late June. On the coast there are many fishing bases with all amenities. Fishing in the Caspian is a great pleasure. In any part of it, including major cities, the catch is unusually rich.
The lake is famous for its large variety of waterfowl.. Geese, ducks, loons, gulls, waders, sea eagles, geese, swans and many others come to the Caspian during migration or nesting.
The largest number of birds - over 600 thousand individuals is observed in the mouths of the Volga and the Urals, in the bays of Turkmenbashi and Kyzylagach. During the hunting season, a huge number of fishermen come here not only from Russia, but also from countries near and far abroad.
Nerpa Caspian
The only mammal lives in the Caspian Sea. This is the Caspian seal or seal. Until recently, the seals swam close to the beaches, everyone could admire the amazing animal with round black eyes, the seals behaved very friendly.
Now the seal is on the verge of extinction.
Cities on the Caspian Sea
Baku is the largest city on the coast of the Caspian Sea..
The number of one of the most most beautiful cities of the world is over 2.5 million people. Baku is spread out on the most picturesque Absheron peninsula and is surrounded on three sides by the waters of the warm and oil-rich Caspian Sea.
Smaller cities: the capital of Dagestan is Makhachkala, Kazakh Aktau, Turkmen Turkmenbashi and Iranian Bandar Anzeli.
Baku Bay, Baku - a city on the Caspian Sea
Interesting Facts
Scientists are still arguing about whether to call a reservoir a sea or a lake.
The level of the Caspian Sea is gradually decreasing.
The Volga delivers most of the water to the Caspian.
90% of black caviar is mined in the Caspian Sea. Among them, the most expensive is Almas beluga caviar ($2,000 per 100 g).
In developing oil fields The Caspian Sea is attended by companies from 21 countries. According to Russian estimates, hydrocarbon reserves in the sea amount to 12 billion tons.
American scientists claim that one fifth of the world's hydrocarbon reserves are concentrated in the depths of the Caspian Sea. This is more than the combined reserves of such oil-producing countries as Kuwait and Iraq.
The Caspian Sea is the largest enclosed body of water. And although the water in it is salty, and the bed is lined with rocks of the oceanic type, it is located at a distance from the oceans and is a giant drainless lake.
The Caspian Sea is located in two parts of the world at once. Its western shore washes the European part of the mainland, and the eastern one is part of Asia. Its length from north to south is 1030 km, and from west to east 435 km at the maximum point. Sea coordinates: 36°34'–47°13' north latitude and 46°–56° east longitude.
You can get to the Caspian Sea from anywhere in Russia. One of the main destinations for the Russians will be Astrakhan and the region, with which both air and rail flights go from the capital and other large cities all year round. It is not so easy to get from remote cities, as often the stations do not make direct flights to Astrakhan.
Another popular route runs through Dagestan and leads to Makhachkala, Kaspiysk or Derbent - the main cities for tourists. Planes from Moscow, St. Petersburg, Yekaterinburg and Krasnoyarsk fly to the capital of the republic all year round. It is also possible to get there by train, but in summer they are usually packed with people.
Historical facts
The lake was formed from the Sarmatian Sea tens of millions of years ago, when the Caucasus Mountains did not divide it into the Black and Caspian Sea. The Sarmatian Sea itself finally lost direct access to the ocean more than 70 million years ago.
One of the first written references to the Caspian was found on clay tablets dating back to the 9th century. BC e. They were found during excavations in Assyria, the territory of which mainly belongs to modern Iraq and Syria. Later, Herodotus, Aristotle and the "father of geography" Hecateus of Miletus mention the Caspian. Their knowledge was generalized and expanded by Arab scientists in the 9th-10th centuries.
How was the Caspian Sea formed?
With the development of medieval trade relations Information about the Caspian Sea also spread to Europe and Turkey. The famous navigator and traveler Marco Polo described it in the 13th century. With the further passage of time, knowledge about the lake was only replenished, more detailed and truthful maps were created.
As for the name, over the thousands of years of its existence on it, people have given the lake more than 70 names. So, the ancient peoples called it Hyrcanian, and the Arabs - Khazar. The Chinese gave it the name Sihai, the Iranians - Kolzum, the Turks - Kyuchuk-Deniz.
The Russians called it the "Blue Sea", Khvalynsky or Khozemsky. The name also changed depending on the neighboring states. At one time it was also called Sarai, Turkmen, Avar, Persian and many other names. It took its modern name from the ancient nomadic pastoral tribes - the Caspians, who lived on its right bank around the 2nd millennium BC.
Characteristic
Of all the characteristics of the Caspian, the most interesting are its unique flora and fauna, which have collected many rare species of plants and animals, the determination of its origin and the problems associated with the ecology and pollution of the reservoir.
Bottom relief and depth
The Caspian Sea is divided into three geographical zones: North, Middle and South. The north is a sea plume with medium depth no more than 5 m. It accounts for the smallest amount of lake water - about 1%. The second largest was the Middle Caspian, where the bottom at its maximum point goes to 780 m. It contains more than 30% of water reserves. 
southern part equal to the Average in area, but is deeper and has more than 60% of the water mass.
It is here that the deepest point of the lake is located today - 1025 meters under water.
The boundaries between the parts are rather arbitrary, but they exist.
Between the North and the Middle of the border were the island of Chechen and Cape Tyub-Karagansky, and between the Middle and the South - the island of Zhiloy and Cape Gan-Gulu.
The relief of the bottom of the lake is quite uniform, but differs in different zones.
In the North, it is flat shallow water with small alluvial areas. The middle one goes deep and is covered with silt or shells. The southern one, being the deepest one, is also covered with silt, and in some places with ledges of bedrock.
Area and length
The surface area of the lake is approximately 370,000 sq. km. The water level is subject to cyclical changes: it goes down, then it rises. Scientists have found that over the past millennium, the water level in the lake has fluctuated within a dozen meters. This is a very big indicator.
It is connected primarily with the activity of people, as well as geological factors that constantly affect the reservoir. According to confirmed data, the water level is only rising. The South, Middle and North account for 40, 35, 25% of the area, respectively.
The length of the coastline is 6700 km, and taking into account the island territories - about 7000. The coasts themselves are quite smooth, without large hills. In the north, the lowland of the coast is represented by channels and islands formed by the Volga.
The area here is swampy and covered with dense thickets of reeds. The eastern coastal areas are adjacent to deserts and are composed of limestone or shells. The most "mountainous" were the coasts of the Absheron Peninsula and the Kazakh Gulf. 
The Caspian Sea is located in an area where there are many islands and peninsulas. The largest and most significant peninsulas are: the Agrakhan Peninsula, the Absheron Peninsula, on which Baku is located, the Mangyshlak Peninsula, which has the Kazakh city of Aktau, the Buzachi, Miankale and Tyub-Karagan Peninsulas.
There are about 50 large and medium-sized islands in the lake. Their total area is 350 sq. km. The most famous of them are: Chechen, Gum, Dash, Zyanbil, Seal Islands, Chygyl, Garasu and Ashur-Ada.
Water composition
The composition of water is different from that observed in the seas and oceans. This is due not only to the fact that the Caspian Sea is closed, but also subject to a significant influence of the waters of the continental runoff. This greatly reduces the content of chlorides and salts in the water, but increases the amount of calcium, carbonates and sulfates inherent in river water.
In the Sea of Azov, for example, there are two times less calcium cations than in the Caspian. Despite this, the water in the lake is salty - from 0.05 ppm at the confluence of the Volga to 11-13 ppm in the southern part.
| Carbonates (CaCO3) | Sulphates CaSO4, MgSO4 | Chlorides NaCl, KCl, MgCl2 | Average salinity of waters ‰ | |
| Ocean | 0,21 | 10,34 | 89,45 | 35 |
| Caspian Sea | 1,24 | 30,54 | 67,90 | 12,9 |
The basin of the sea and its relationship with the oceans
The Caspian Sea basin is 3.1 million sq. km. km. It includes such rivers as the Volga, Kuma, Uluchay, Samug, Sudak, Terek. The Volga is the largest and deep river flowing into the lake. More than two hundred major rivers, and the number of its tributaries is more than 5000.
From the Astrakhan region begins its delta, which is the largest in Europe. The Volga receives most of its water from melting snow, rain and springs. In addition to these rivers, more than 100 rivers flow into the Caspian.
To date, the Caspian Sea has no direct connection with the ocean, however, an indirect connection is provided through the Volga-Don Canal. Through it, ships and fleets can get from the Caspian and Volga to the Don, Azov and Black Sea.
Climate
The Caspian Sea is within a few climatic zones, and the climate depends on its parts. In the northern part, it is continental with temperatures ranging from -10 °C in winter to +25 °C in summer. In the southern part, the climate becomes subtropical. The temperature there ranges from + 8 °C in winter to +27 °C in summer. 
The middle part of the Caspian Sea is located in temperate climate with average temperatures. The most heat registered on the east coast and amounted to +44 °C.
Water temperature is also subject to significant changes and depends on latitude. During the cold season in the northern part, the water can freeze or cool to 0 - 1 °C, and in the south the temperature does not fall below 10 °C. In summer, the water warms up from +20 °C to +27 °C, depending on the region.
As for precipitation, their average annual rate is 200 mm. Again, it all depends on the climate and varies from 100 mm in the eastern part to 1700 mm in the southern subtropics. It is best to visit the Caspian Sea in the summer at the end of July or in August. Ideal resorts will be Baku, Makhachkala and Astrakhan.
Flora and fauna
The fauna of the Caspian Sea is diverse and rich. It somewhat repeats other reservoirs, but is peculiar in its own way. Ancient sturgeon and salmon species of fish live here, as well as several types of herring, carp, pike perch, carp, sprat, mullet, bream, pike, and vobla. There are about 100 species of fish in total. 
The volume of sturgeon makes up 90% of all world stocks. The only and unique species of mammal living in this area is the Caspian seal, which is the smallest of all seals. Many of the species are protected by three reserves: Astrakhan, Caspian and Gyzylagadzh.
The vegetation has more than 700 species. The most significant for maintaining favorable conditions for animals are blue-green, red, brown and diatoms. Flora is mostly neogene period of the ancient Caspian, however, some species are brought into the sea on purpose or accidentally in connection with shipping.
Ecological situation
The current ecological situation in the Caspian Sea is not the best. The main polluting factor was oil and its processing. As you know, it began to be mined here 150 years ago in Azerbaijan.
In this regard, the suppression of the development of finoplankton and blue-green algae began, the concentration of oxygen in the water decreased, which affected the reproduction of sturgeon fish, waterfowl and other living organisms. 
A lot of troubles were also brought by the mass reproduction of the comb jelly Mnemiopsis, which penetrated into the Caspian Sea from the Black and Azov Seas through the Volga-Don Canal. The comb jelly feeds on the same plankton as the Caspian fish.
This reduced their food base and put sturgeon on the brink of extinction. Number of valuable sturgeon fish links with poaching, which, according to unofficial data, account for more than half of the catch, have also decreased.
Unique in nature, the biological and hydrocarbon resources of the Caspian Sea are also destroyed by phenols and heavy metals that enter it with sewage industrial enterprises located near the reservoir.
Countries washed by the Caspian Sea
The waters of the sea wash the territories of modern:
The main cities located on the coast are Astrakhan, Baku, Aktau, Bender-Anzeli, Makhachkala and Turkmenbashi.
Tourism infrastructure on the Caspian Sea
The Caspian Sea is located around developed countries and its tourist infrastructure is represented by a large number of coastal resort towns with many recreation centers and hotels. Tourists have at their disposal not only active recreation in the form of fishing or water parks, but also beaches where, for little money, you can relax from morning to late evening, renting sun loungers, hammocks or gazebos.
Resorts on the Caspian Sea
Baku has become one of the most prestigious resorts. The capital of Azerbaijan with a population of 2.5 million people provides an opportunity not only to relax on the beach, but also to visit many attractions, some of which are included in the UNESCO World Heritage List.
It is still better to go to the beaches in the suburbs of Baku, where Shikhovo, Mardakan or Zagulba are located. The resort infrastructure of the Caspian Sea is at a high level. The beaches are clean and well maintained, hotel complexes provide a wide range of accommodation near the coast. V
All this is a 30-minute drive from Baku. Do not write off Sumgayit either. It is located 30 km from Baku, but has more extensive shell-type beaches. It has less city fuss, but service and maintenance are not inferior to the capital. 
Kazakhstan also has several resorts in major cities. Aktau and Atyrau became the most popular. Despite the fact that Aktau is located in the desert and began to recreate the tourism infrastructure relatively recently, it has new hotel complexes with a decent quality of service.
Atyrau, on the other hand, has ceased to be in demand, since the Caspian Sea has become shallow in these places and the beaches have ceased to exist. In general, Kazakh resorts are in low demand among foreign and Russian vacationers.
The Caspian Sea washes several large Turkmen cities, including Turkmenbashi and Avaza. The second city enjoys tourist demand. Here, the construction of hotels and complexes also began relatively recently, but the resort has already managed to find its adherents.
One of its features are sand and shell beaches stretching for kilometers. The resorts of Turkmenistan also cannot be called popular among foreigners, since there is a rather complicated visa system when entering the country.
In Russia, the main popular are the two resorts of Astrakhan and Dagestan, represented by Astrakhan itself, Makhachkala, Derbent, Caspian and a couple of other small towns. One of the most picturesque is Derbent. Thanks to its landscapes and ancient buildings, which are part of the UNESCO heritage, the city has become popular not only among tourists from Russia, but also among foreigners.
Beaches on the Caspian Sea
Most interesting beaches Russian resorts became Jami, Goryanka, Laguna and the beach of the Caspian sanatorium, located on the territory of Dagestan. Unfortunately, according to the reviews of tourists in Astrakhan, there are few good beaches, and most of the coastal areas are in the thickets of reeds. 
Jami Beach, like the Caspian, belongs to hotel and sanatorium apartments located on the coast. That is why they are well equipped in terms of recreation and service. Goryanka beach is different in that only women and boys under 6 years old can enter its territory.
Among the beaches of Kazakhstan, the beaches of Manila, Nur Plaza, Dostar, Marrakesh deserve the most attention. The beaches of Manila and new Marrakesh are very popular, as the entrance to them is free, and they are open until late in the evening.
Nur Plaza and Dostar are paid. Entrance costs from 35 to 80 rubles. This price already includes umbrellas, sun loungers and other benefits. It is possible to cheaply rent gazebos, barbecues and park cars.
The beaches of the Turkmen Avaza stretch for 30 km and have good infrastructure and huge hotel complexes. But not everything is so good. Many note the many shortcomings of hotels and service for rather high ticket prices. Among them: cold water in the sea, low population, smells from oil refineries, which are located near the Caspian Sea. 
The beaches of Azerbaijan are rightfully considered the most developed. There are a lot of them for every taste and budget. Almost the entire coastal zone of Baku is built up with hotel complexes, recreation centers and beaches.
The most famous is the beach of the water park Shikhovo. It has everything for active rest not only adults, but also children. Water slides and attractions will not make you bored, and a large number of sun loungers will fit everyone who wants to just lie in the sun. But do not forget about such beaches as Nabran, Sumgaiti, Novkhani and other places.
Sights of the Caspian Sea
On the territory of Russia there are many attractions that are worth visiting when arriving at the resort. In Astrakhan, they were the Astrakhan Kremlin, the Bridge of Lovers, the Wedding Waltz fountain. In Makhachkala, you can visit the Juma Mosque, many museums and theaters, and in Derbent, the ancient Naryn-Kala fortress and the 150-year-old Derbent lighthouse often become a place of visit. 
Azerbaijan has unique architectural objects of its kind. In the suburbs of Baku, there is the Maiden Tower and a whole complex of walls with the palace of the Shirvanshahs, the Gobustan landscape with ancient rock paintings. There is something to see in the city center. Here are modern hotels, galleries and museums. For example, the Carpet Museum, the TV tower, the cultural center of Heydar Aliyev.
There are not so many sights in the Turkmen Avaza. Among them are several yacht clubs, a park, a Congress Center and an aqua park with attractions. There are no special sights in Kazakh Aktau, as well as streets. The whole city is divided into districts.
Entertainment and active recreation on the Caspian Sea
For people who love outdoor activities, there are special fishing tours to Astrakhan. Prices start from 20,000 rubles. and include accommodation, boat rentals, fish freezing and cooking facilities.
In Kazakhstan, for outdoor enthusiasts, there are bases with fitness centers, shady courts and much more. Among them, the Kenderly base stands out. Its only drawback: it is located 300 km from the coast. 
On the Azerbaijani coast there is everything for a good time. Water parks Shikhov and Resort will not let children and adults who love active entertainment. Like the Turkmen water park in Avaza.
Prices for hotels in the Caspian Sea
Resort prices in Russia are the cheapest. Accommodation in apartments in Astrakhan will cost 600-700 rubles, and in hotels from 1200 to 3600 rubles. per day. The most popular hotels are Corvette, Bonhotel, Novomoskovsky. In Dagestan, the average price for a hotel will be 1,500 rubles. Coastal hotels: Argo, Pegasus, Assorted, Sharhistan, Versailles.
In Kazakh Aktau there are hotels Rakhat, Aktau, Victoria. Prices depend on the quality of services, but on average they start from 2,000 thousand rubles. Renting an apartment starts from 600 rubles.
Baku hotels provide the best conditions and service, however, the prices here are by no means the highest. average price is 2000 rubles. Popular hotels are Consul, Bosfor, Safran. It is also possible to rent apartments and individual rooms.
But Turkmen hotels are the most expensive. Prices here start at $70. Despite this, many complain that for such money the service leaves much to be desired.
The Caspian Sea is a unique body of water with its own original flora and fauna. There are 5 states on its shores, most of which provide good tourist infrastructure and services at affordable prices. In coastal cities, there are ancient sights that are world heritage UNESCO.
Article formatting: Mila Fridan
Video about the Caspian Sea
Overview of holidays on the Caspian Sea:
V. N. MIKHAILOV
The Caspian Sea is the largest drainless lake on the planet. This body of water is called the sea for its huge size, brackish water and sea-like regime. The level of the Caspian Sea-lake lies much lower than the level of the World Ocean. At the beginning of 2000, he had a mark of about - 27 abs. m. At this level, the area of the Caspian Sea is ~ 393 thousand km2 and the volume of water is 78,600 km3. The average and maximum depths are 208 and 1025 m, respectively.
The Caspian Sea is elongated from south to north (Fig. 1). The Caspian washes the shores of Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran. The reservoir is rich in fish, its bottom and banks are rich in oil and gas. The Caspian Sea is quite well studied, but many mysteries remain in its regime. The most characteristic reservoir - this is the instability of the level with sharp drops and rises. The last rise in the level of the Caspian took place before our eyes from 1978 to 1995. It gave rise to many rumors and speculation. Numerous publications appeared in the press, which spoke about catastrophic floods and ecological catastrophe. It was often written that the rise in the level of the Caspian Sea led to the flooding of almost the entire Volga delta. What is true in the statements made? What is the reason for such behavior of the Caspian Sea?
WHAT HAPPENED TO THE CASPIAN IN THE 20TH CENTURY
Systematic observations over the level of the Caspian Sea were started in 1837. In the second half of the 19th century, the average annual values of the Caspian Sea level were in the range of marks from -26 to -25.5 abs. m and showed a slight downward trend. This trend continued into the 20th century (Fig. 2). In the period from 1929 to 1941, the sea level dropped sharply (by almost 2 m - from - 25.88 to - 27.84 abs. m). In subsequent years, the level continued to fall and, having decreased by approximately 1.2 m, reached in 1977 the lowest mark for the observation period - 29.01 abs. m. Then the sea level began to rise rapidly and, having risen by 2.35 m by 1995, reached a mark of 26.66 abs. m. In the next four years average level sea decreased by almost 30 cm. Its average marks were - 26.80 in 1996, - 26.95 in 1997, - 26.94 in 1998 and - 27.00 abs. m in 1999.
The decrease in sea level in the years 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 level drop. There were many more negative consequences. With a decrease in the level, the areas of forage land for fish stocks in the northern Caspian have decreased. The shallow estuarine coast of the Volga began to quickly overgrow with aquatic vegetation, which worsened the conditions for the passage of fish to spawn in the Volga. Catches of fish, especially valuable species such as sturgeon and sterlet, have sharply decreased. Shipping began to suffer damage due to the fact that the depths in the approach channels decreased, especially near the Volga delta.
The rise in the level from 1978 to 1995 was not only unexpected, but also led to even greater negative consequences. After all, both the economy and the population of coastal areas have already adapted to a low level.
Many sectors of the economy began to suffer damage. Significant territories turned out to be in the zone of flooding and flooding, especially in the northern (flat) part of Dagestan, in Kalmykia and the Astrakhan region. The cities of Derbent, Kaspiysk, Makhachkala, Sulak, Caspian (Lagan) and dozens of other smaller settlements suffered from the level rise. Significant areas of agricultural land have been flooded and flooded. Roads and power lines, engineering structures of industrial enterprises and public utilities are being destroyed. A threatening situation has developed with fish-breeding enterprises. Abrasion processes in the coastal zone and the effect of sea water surges have intensified. V last years the flora and fauna of the seashore and the coastal zone of the Volga delta suffered significant damage.
In connection with the increase in depth in the shallow waters of the Northern Caspian and the reduction in the areas occupied in these places by aquatic vegetation, the conditions for the reproduction of stocks of anadromous and semi-anadromous fish and the conditions for their migration to the delta for spawning have somewhat improved. However, the predominance of negative consequences from the rising sea level made us speak of an ecological catastrophe. The development of measures to protect national economic objects and settlements from the advancing sea began.
HOW UNUSUAL IS CURRENT CASPIAN BEHAVIOR?
Research into the life history of the Caspian Sea can help answer this question. Of course, there are no data from direct observations of the past regime of the Caspian Sea, but there are archaeological, cartographic and other evidence for historical time and the results of paleogeographic studies covering a longer period.
It is proved that during the Pleistocene (the last 700-500 thousand years) the level of the Caspian Sea underwent large-scale fluctuations in the range of about 200 m: from -140 to + 50 abs. m. In this period of time in the history of the Caspian, four stages are distinguished: Baku, Khazar, Khvalyn and New Caspian (Fig. 3). Each stage included several transgressions and regressions. The Baku transgression occurred 400-500 thousand years ago, the sea level rose to 5 abs. m. During the Khazar stage, there were two transgressions: the early Khazar (250-300 thousand years ago, the maximum level is 10 abs. m) and the late Khazar (100-200 thousand years ago, the highest level is 15 abs. m). The Khvalyn stage in the history of the Caspian included two transgressions: the largest for the Pleistocene period, the early Khvalyn (40-70 thousand years ago, the maximum level is 47 abs. m, which is 74 m higher than the modern one) and the late Khvalyn (10-20 thousand years ago, the rise level up to 0 abs. m). These transgressions were separated by a deep Enotaevskaya regression (22-17 thousand years ago), when the sea level dropped to -64 abs. m and was 37 m lower than the modern one.
Rice. 4. Fluctuations in the level of the Caspian Sea over the past 10 thousand years. P is the natural range of fluctuations in the level of the Caspian Sea under climatic conditions characteristic of the subatlantic epoch of the Holocene (risk zone). I-IV - stages of the New Caspian transgression; M - Mangyshlak, D - Derbent regression
Significant fluctuations in the level of the Caspian also occurred during the New Caspian stage of its history, which coincided with the Holocene (the last 10 thousand years). After the Mangyshlak regression (10 thousand years ago, a level decrease to -50 abs. m), five stages of the New Caspian transgression were noted, separated by small regressions (Fig. 4). Following sea level fluctuations, its transgressions and regressions, the outline of the reservoir also changed (Fig. 5).
Over the historical time (2000 years), the range of changes in the average level of the Caspian Sea was 7 m - from - 32 to - 25 abs. m (see Fig. 4). The minimum level in the last 2000 years was during the Derbent regression (VI-VII centuries AD), when it decreased to - 32 abs. m. During the time that has passed since the Derbent regression, the average sea level has changed in an even narrower range - from -30 to -25 abs. m. This range of level changes is called the risk zone.
Thus, the level of the Caspian has experienced fluctuations before, and in the past they were more significant than in the 20th century. Such periodic fluctuations are a normal manifestation of the unstable state of a closed reservoir with variable conditions at the outer boundaries. Therefore, there is nothing unusual in the lowering and rising of the level of the Caspian Sea.
Fluctuations in the level of the Caspian Sea in the past, apparently, did not lead to the irreversible degradation of its biota. Of course, sharp drops in sea level created temporary unfavorable conditions, for example, for fish stocks. However, with the rise in the level, the situation corrected itself. natural conditions coastal zone (vegetation, benthic animals, fish) experience periodic changes along with fluctuations in sea level and, apparently, have a certain margin of stability and resistance to external influences. After all, the most valuable sturgeon herd has always been in the Caspian basin, regardless of fluctuations in sea level, quickly overcoming the temporary deterioration of living conditions.
Rumors that rising sea levels have caused flooding throughout the Volga Delta have not been confirmed. Moreover, it turned out that the increase in water levels, even in the lower part of the delta, is inadequate to the magnitude of the sea level rise. The increase in the water level in the lower part of the delta during the low water period did not exceed 0.2-0.3 m, and almost did not manifest itself during the flood. At the maximum level of the Caspian Sea in 1995, the backwater from the sea extended 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. Flooding in the upper and middle parts of the delta was associated with high floods in 1991 and 1995 (which is normal for the Volga delta) and with the unsatisfactory condition of protective dams. The reason for the weak effect of sea level rise on the regime of the Volga delta is the presence of a huge shallow coastal zone, which dampens the effect of the sea on the delta.
With regard to the negative impact of sea level rise on the economy and life of the population in the coastal zone, the following should be recalled. At the end of the last century, the sea level was higher than at present, and this was in no way perceived as ecological catastrophy. And before the level was even higher. Meanwhile, Astrakhan has been known since the middle of the 13th century, and Sarai-Batu, the capital of the Golden Horde, was located here in the 13th - mid-16th centuries. These and many more settlements on the coast of the Caspian Sea did not suffer from high level standing, since they were located on elevated places and at abnormal flood levels or during surges, people temporarily moved from low places to higher ones.
Why, then, are the consequences of a rise in sea level even to smaller levels now perceived as a catastrophe? The cause of the enormous damage that National economy, is not a rise in the level, but a thoughtless and short-sighted development of a strip of land within the mentioned risk zone, released (as it turned out, temporarily!) From under the sea level after 1929, that is, when the level drops below the mark - 26 abs. m. The buildings erected in the risk zone, of course, turned out to be flooded and partially destroyed. Now, when the territory developed and polluted by man is flooded, a dangerous ecological situation is really created, the source of which is not natural processes, but unreasonable economic activity.
ABOUT THE REASONS FOR THE CASPIAN LEVEL FLUCTUATIONS
Considering the question of the causes of fluctuations in the level of the Caspian Sea, it is necessary to pay attention to the confrontation in this area of two concepts: geological and climatic. Significant contradictions in these approaches were revealed, for example, at the international conference "Caspian-95".
According to the geological concept, two groups of processes are attributed to the causes of changes in the level of the Caspian Sea. The processes of the first group, according to geologists, lead to a change in the volume of the Caspian depression and, as a result, to changes in sea level. Such processes include vertical and horizontal tectonic movements. earth's crust, accumulation of bottom sediments and seismic phenomena. The second group includes processes that, as geologists believe, affect the underground runoff into the sea, either increasing it or decreasing it. Such processes are called periodic extrusion or absorption of water, which saturate bottom sediments under the influence of changing tectonic stresses (changes in periods of compression and tension), as well as technogenic destabilization of the subsoil due to oil and gas production or underground nuclear explosions. It is impossible to deny the fundamental possibility of the influence of geological processes on the morphology and morphometry of the Caspian depression and underground runoff. However, at present, the quantitative relationship of geological factors with fluctuations in the level of the Caspian Sea has not been proven.
There is no doubt that tectonic movements played a decisive role in the initial stages of the formation of the Caspian depression. However, if we take into account that the Caspian Sea basin is located within a geologically heterogeneous territory, which results in periodic rather than linear tectonic movements with repeated sign changes, then one should hardly expect a noticeable change in the capacity of the basin. Not in favor of the tectonic hypothesis is the fact that the coastlines of the New Caspian transgressions in all sections of the Caspian coast (with the exception of certain areas within the Apsheron archipelago) are at the same level.
There are no grounds to consider the change in the capacity of its basin due to the accumulation of precipitation as the reason for fluctuations in the level of the Caspian Sea. The rate of filling the basin with bottom sediments, among which the main role is played by river runoff, is estimated, according to modern data, at a value of about 1 mm/year or less, which is two orders of magnitude less than the currently observed changes in sea level. Seismic deformations, which are observed only near the epicenter and attenuate at close distances from it, cannot have any significant effect on the volume of the Caspian Basin.
As for the periodic large-scale discharge of groundwater into the Caspian Sea, its mechanism is still unclear. At the same time, this hypothesis is contradicted, according to E.G. Maev, firstly, the undisturbed stratification of interstitial waters, indicating the absence of noticeable migrations of waters through the thickness of bottom sediments, and secondly, the absence of proven powerful hydrological, hydrochemical and sedimentation anomalies in the sea, which should have accompanied a large-scale discharge of groundwater capable of affect changes in water levels.
The main evidence of the insignificant role of geological factors at present is a convincing quantitative confirmation of the plausibility of the second, climatic, or rather, water-balance concept of fluctuations in the Caspian level.
CHANGES IN THE COMPONENTS OF THE CASPIAN WATER BALANCE AS THE MAIN CAUSE OF ITS LEVEL FLUCTUATIONS
For the first time, fluctuations in the level of the Caspian Sea were explained by a change climatic conditions(more specifically, the runoff of rivers, evaporation and precipitation on the surface of the sea) by E.Kh. Lenz (1836) and A.I. Voeikov (1884). Later, the leading role of changes in the components of the water balance in sea level fluctuations was again and again proved by hydrologists, oceanologists, physicogeographers and geomorphologists.
The key to most of the studies mentioned is the compilation of the water balance equation and the analysis of its components. The meaning of this equation is as follows: the change in the volume of water in the sea is the difference between the incoming (river and underground runoff, atmospheric precipitation on the sea surface) and outgoing (evaporation from the sea surface and outflow of water into the Kara-Bogaz-Gol Bay) components of the water balance. The change in the level of the Caspian is the quotient of dividing the change in the volume of its waters by the area of the sea. The analysis showed that the leading role in the water balance of the sea belongs to the ratio of the flow of the Volga, Ural, Terek, Sulak, Samur, Kura rivers and visible or effective evaporation, the difference between evaporation and precipitation on the surface of the sea. An analysis of the components of the water balance revealed that the largest contribution (up to 72% of the dispersion) to the level variability comes from the inflow of river waters, and more specifically, the runoff formation zone in the Volga basin. As for the reasons for the change in the flow of the Volga itself, they are associated, as many researchers believe, with the variability of atmospheric precipitation (mainly winter) in the river basin. And the mode of precipitation, in turn, is determined by the circulation of the atmosphere. It has long been proven that the latitudinal type of atmospheric circulation contributes to an increase in precipitation in the Volga basin, while the meridional type contributes to a decrease.
V.N. Malinin revealed that the root cause of moisture entering the Volga basin should be sought in the North Atlantic, and specifically in the Norwegian Sea. It is there that the increase in evaporation from the sea surface leads to an increase in the amount of moisture transferred to the continent, and, accordingly, to an increase in atmospheric precipitation in the Volga basin. The latest data on the water balance of the Caspian Sea, received by the staff of the State Oceanographic Institute R.E. Nikonova and V.N. Bortnik, are given with the author's clarifications in Table. 1. These data convincingly prove that the main reasons for both the rapid drop in sea level in the 1930s and the sharp rise in 1978-1995 were changes in river flow, as well as apparent evaporation.
Keeping in mind that river runoff is one of the main factors affecting the water balance and, as a result, the level of the Caspian Sea (and the Volga runoff provides at least 80% of the total river runoff in the sea and about 70% of the incoming part of the Caspian water balance), it would be interesting to find a connection between sea level and the flow of one Volga, measured most accurately. Direct correlation of these quantities does not give satisfactory results.
However, the relationship between the sea level and the Volga runoff is well traced if the river runoff is not taken into account for each year, but the ordinates of the difference integral runoff curve are taken, that is, the sequential sum of the normalized deviations of the annual runoff values from the long-term average value (norm). Even a visual comparison of the course of the average annual levels of the Caspian Sea and the difference integral curve of the Volga runoff (see Fig. 2) makes it possible to reveal their similarity.
For the entire 98-year period of observations of the Volga runoff (the village of Verkhneye Lebyazhye at the head of the delta) and the sea level (Makhachkala), the correlation coefficient of the relationship between the sea level and the ordinates of the difference integral runoff curve was 0.73. If we discard years with small level changes (1900-1928), then the correlation coefficient increases to 0.85. If for analysis we take a period with a rapid decline (1929-1941) and a rise in the level (1978-1995), then the overall correlation coefficient will be 0.987, and separately for both periods 0.990 and 0.979, respectively.
The presented calculation results fully confirm the conclusion that during periods of a sharp decrease or rise in sea level, the levels themselves are closely related to the runoff (more precisely, to the sum of its annual deviations from the norm).
A special task is to assess the role of anthropogenic factors in fluctuations in the level of the Caspian Sea, and above all, the reduction in river flow due to its irretrievable losses for filling reservoirs, evaporation from the surface of artificial reservoirs, and water withdrawal for irrigation. It is believed that since the 1940s, irretrievable water consumption has been steadily increasing, which has led to a reduction in the inflow of river waters to the Caspian Sea and an additional decrease in its level compared to the natural one. According to V.N. Malinin, by the end of the 1980s, the difference between the actual sea level and the restored (natural) level reached almost 1.5 m. about 26 km3/year). If it were not for the withdrawal of river runoff, then the rise in sea level would have begun not at the end of the 70s, but at the end of the 50s.
The increase in water consumption in the Caspian basin by 2000 was predicted first to 65 km3/year, and then to 55 km3/year (36 of them were in the Volga). Such an increase in irretrievable losses of river runoff should have lowered the level of the Caspian by more than 0.5 m by 2000. In connection with the assessment of the impact of irreversible water consumption on the level of the Caspian, we note the following. First, estimates of water withdrawal volumes and evaporation losses from the surface of reservoirs in the Volga basin found in the literature are apparently significantly overestimated. Secondly, forecasts of water consumption growth turned out to be erroneous. The forecasts included the rate of development of water-consuming sectors of the economy (especially irrigation), which not only turned out to be unrealistic, but also gave way to a decline in production in recent years. In fact, as A.E. Asarin (1997), by 1990 water consumption in the Caspian basin was about 40 km3/year, and has now decreased to 30-35 km3/year (in the Volga basin to 24 km3/year). Therefore, the "anthropogenic" difference between the natural and actual sea levels is currently not as large as predicted.
ON POSSIBLE FLUCTUATIONS OF THE CASPIAN LEVEL IN THE FUTURE
The author does not set himself the goal of analyzing in detail the numerous forecasts of fluctuations in the level of the Caspian Sea (this is an independent and difficult task). The main conclusion from the assessment of the results of forecasting fluctuations in the level of the Caspian can be drawn as follows. Although the forecasts were based on completely different approaches (both deterministic and probabilistic), there was not a single reliable forecast. The main difficulty in using deterministic forecasts based on the sea water balance equation is the lack of development of the theory and practice of ultra-long-term forecasts of climate change over large areas.
When the sea level decreased in the 30-70s, most researchers predicted its further fall. In the last two decades, when sea level rise began, most forecasts predicted an almost linear and even accelerating rise in level to -25 and even -20 abs. m and above at the beginning of the XXI century. In this case, three factors were not taken into account. First, the periodic nature of fluctuations in the level of all endorheic reservoirs. The instability of the Caspian level and its periodic nature are confirmed by the analysis of its current and past fluctuations. Secondly, at sea level close to - 26 abs. m, the flooding of large sor bays on the northeastern coast of the Caspian Sea - Dead Kultuk and Kaydak, as well as low-lying territories in other places of the coast, which have dried up at a low level, will begin. This would lead to an increase in the area of shallow waters and, as a consequence, an increase in evaporation (up to 10 km3/year). With a higher sea level, the outflow of water to Kara-Bogaz-Gol will increase. All this should stabilize or at least slow down the level growth. Thirdly, level fluctuations under the conditions of the modern climatic epoch (the last 2000 years), as shown above, are limited by the risk zone (from -30 to -25 abs. m). Taking into account the anthropogenic decrease in runoff, the level is unlikely to exceed the mark of 26-26.5 abs. m.
The decrease in average annual levels in the last four years by a total of 0.34 m, possibly indicates that in 1995 the level reached its maximum (-26.66 abs. m), and a change in the trend of the Caspian level. In any case, the prediction that the sea level is unlikely to exceed 26 abs. m, apparently justified.
In the 20th century, the level of the Caspian Sea changed within 3.5 m, first dropping and then rising sharply. 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 runoff, precipitation on the sea surface) and outgoing (evaporation from the surface of the reservoir, outflow to the Kara-Bogaz-Gol Bay) components of the Caspian water balance corresponds to its own level of equilibrium. Since the components of the water balance of the sea also change under the influence of climatic conditions, the level of the reservoir fluctuates, trying to reach an equilibrium state, but never reaches it. Ultimately, the trend of changing the level of the Caspian in given time depends on the ratio of precipitation minus evaporation in the watershed (in the basins of the rivers that feed it) and evaporation minus precipitation over the reservoir itself. There is really nothing unusual about the recent rise of the Caspian Sea level by 2.3 m. Such level changes have occurred many times in the past and did not cause irreparable damage to the natural resources of the Caspian. The current rise in sea level has become a catastrophe for the economy of the coastal zone only because of the unreasonable development of this risk zone by man.
Vadim Nikolaevich Mikhailov, doctor geographical sciences, Professor of the Department of Terrestrial Hydrology, Faculty of Geography, Moscow State University, Honored Scientist of the Russian Federation, full member of the Academy of Water Management Sciences. Area of scientific interests - hydrology and water resources, interaction of rivers and seas, deltas and estuaries, hydroecology. Author and co-author of about 250 scientific papers, including 11 monographs, two textbooks, four scientific and methodological manuals.
