Caspian lake. Why is the Caspian lake called the sea? Interesting facts about the Caspian Sea: depth, relief, coastline, resources

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 rivers Volga, Ural, Emba, Terek (total annual flow of 88% of the total river flow into the sea) flow 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

Climate in the Caspian Sea

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 long-term average 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 the 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 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 peculiarity of the salt composition of the Caspian Sea water - 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 mixing depth has significantly increased, 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 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 simultaneously considered both an endorheic lake and a full-fledged sea. The reasons for this confusion are brackish waters and a marine-like hydrological regime.

The Caspian Sea is located on the border of Asia and Europe. Its area is about 370 thousand km 2, the maximum depth is just over one kilometer. The Caspian has a conditional division into three almost equal parts: Southern (39% of the area), Middle (36%) and Northern (25%).

The sea washes simultaneously Russian, Kazakh, Azerbaijani, Turkmen and Iranian shores.

Coast of the Caspian Sea(Caspian) has a length of about 7 thousand kilometers, if you count together with the islands. In the north, the low sea coast is covered with swamps and thickets, and has multiple water channels. The eastern and western coasts of the Caspian have a winding shape, in some places the coasts are covered with limestone.

There are many islands in the Caspian Sea: Dash-Zira, Kyur Dashi, Dzhambaisky, Boyuk-Zira, Gum, Chigil, Khere-Zira, Zenbil, Ogurchinsky, Tyuleniy, Ashur-Ada, etc. Peninsulas: Mangyshlak, Tyub-Karagan, Absheron and Miankale. Their total area is approximately 400 km2.

flows into the Caspian Sea more than a hundred different rivers, the most significant are the Ural, Terek, Volga, Atrek, Emba, Samur. Almost all of them provide the sea with 85-95% of the annual runoff.

The largest bays of the Caspian Sea: Kaydak, Agrakhansky, Kazakh, Dead Kultuk, Turkmenbashi, Mangyshlak, Gyzlar, Girkan, Kaydak.

Climate of the Caspian

The Caspian is located in three climatic zones at once: subtropical climate in the south, continental in the north and temperate in the middle part. In winter, the average temperature varies from -10 to +10 degrees, while in summer the air warms up to about +25 degrees. During the year falls from 110 mm of precipitation in the east and up to 1500 mm in the west.

The average wind speed is 3–7 m/s, but in autumn and winter it often increases to 35 m/s. The most blown areas are the coastal regions of Makhachkala, Derbent and the Absheron Peninsula.

Water temperature in the Caspian Sea fluctuates from zero to +10 degrees in winter, and from 23 to 28 degrees in summer months. In some coastal shallow waters, the water can warm up to 35‒40 degrees.

Only the northern part of the sea is subject to freezing, but in especially cold winters, the coastal zones of the Middle Part are added to it. The ice cover appears in November and disappears only in March.

Problems of the Caspian region

Water pollution is one of the main environmental problems of the Caspian. Oil production, various harmful substances from flowing rivers, waste products from nearby cities - all this adversely affects the state of sea water. Additional troubles are created by poachers, whose actions reduce the number of fish of certain species found in the Caspian Sea.

Sea level rise also causes serious financial damage to all the Caspian countries.

According to conservative estimates, the restoration of destroyed buildings and the implementation of comprehensive measures to protect the coast from flooding costs tens of millions of dollars.

Cities and resorts on the Caspian Sea

The largest city and port washed by the waters of the Caspian Sea is Baku. Among other settlements of Azerbaijan, located in close proximity to the sea, are Sumgayit and Lankaran. On the eastern shores is the city of Turkmenbashi, and about ten kilometers from it by the sea is the large Turkmen resort of Avaza.

On the Russian side, the following cities are located on the seashore: Makhachkala, Izberbash, Derbent, Lagan and Kaspiysk. Astrakhan is also often called a port city, although it is located about 65 kilometers from the northern shores of the Caspian Sea.

Astrakhan

Beach holidays in this region are not provided: along the sea coast there are only continuous reed thickets. However, tourists go to Astrakhan not for idle lying on the beach, but for fishing and various outdoor activities: diving, riding catamarans, jet skis, etc. In July and August, excursion boats ply the Caspian.

Dagestan

For a classic seaside vacation, it is better to go to Makhachkala, Kaspiysk or Izberbash - it is there that not only good sandy beaches are located, but also worthy recreation centers. The range of entertainment on the seashore from the Dagestan side is quite wide: swimming, therapeutic mud springs, windsurfing, kiting, rock climbing and paragliding.

The only disadvantage of this direction is the underdeveloped infrastructure.

In addition, there is an opinion among some Russian tourists that Dagestan is far from the most peaceful territory that is part of the North Caucasian Federal District.

Kazakhstan

Much more relaxed atmosphere can be found in the Kazakh resorts of Kuryk, Atyrau and Aktau. The latter is the most popular tourist city in Kazakhstan: there are many good entertainment venues and well-maintained beaches. In summer, the temperature here is very high, reaching +40 degrees during the daytime, and dropping only to +30 at night.

The disadvantages of Kazakhstan as a tourist country are the same poor infrastructure and rudimentary transport links between regions.

Azerbaijan

Baku, Nabran, Lankaran and other Azerbaijani resorts are considered the best places to relax on the Caspian coast. Fortunately, everything is fine with the infrastructure in this country: for example, several modern comfortable hotels with swimming pools and beaches have been built in the area of ​​the Absheron Peninsula.

However, in order to enjoy relaxing on the Caspian Sea in Azerbaijan, you need to spend a lot of money. In addition, you can get to Baku quickly enough only by plane - trains run rarely, and the journey from Russia itself takes two to three days.

Tourists should not forget that Dagestan and Azerbaijan are Islamic countries, so all "infidels" need to adjust their habitual behavior to local customs.

If you follow the simple rules of your stay, nothing will overshadow your vacation on the Caspian Sea.

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

Caspian Sea

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

The Caspian Sea covers an area of ​​371 thousand km2, the greatest depth is 1025 meters (South Caspian depression). The coastline is estimated from 6500 to 6700 km, and if you take it together with the islands, then more than 7000 km.

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

Bottom relief

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

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

4. Atrek - Turkmenistan;

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

The Caspian Sea belongs to five states. From the west and northwest, the length of the coast of 695 km is the territory of Russia. Most of the coastline with a length of 2320 km belongs to Kazakhstan in the east and northeast. Turkmenistan has 1,200 km in the southeast, Iran has 724 km in the south, and Azerbaijan has 955 km of coastline in the southwest.

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

The main ports are Baku in Azerbaijan; Makhachkala in ; Aktau in Kazakhstan; Olya in Russia; Nowshahr, Bander-Torkemen and Anzeli in Iran.

The largest bays of the Caspian Sea: Agrakhan, Kizlyar, Kaydak, Kazakh, Dead Kultuk, Mangyshlak, Hasan-kuli, Turkmenbashi, Kazakh, Gyzlar, Enzeli, Astrakhan, Gyzlar.

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

Water temperature

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

The climate in the northern part of the sea is continental, in the middle part it is temperate, and in the southern part it is subtropical. On the east coast, the temperature is always higher than on the west. Once on the east coast recorded 44 degrees.

The composition of the Caspian waters

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

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

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

In recent years, there has been a rapid pollution of water by oil products and phenols. Their level already exceeds the permissible level.

Minerals

Back in the 19th century, the beginning of hydrocarbon production was laid. These are the main natural resources. There are also mineral, balneological biological resources here. Today, in addition to gas and oil production, sea-type salts (Astrakhanite, mirabalite, halite), sand, limestone, and clay are mined on the shelf.

Animal and plant world

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

From plants, blue-green algae, brown, red can be noted. Zostera and ruppia also grow, they are classified as flowering algae.

The plankton brought into the sea by birds begins to bloom in spring, the sea is literally covered with greenery, and rhizosolation during flowering paints most of the sea territory in yellow-green color. The accumulation of rhizosolenia is so dense that even waves can calm down. In some places near the coast, literally meadows of algae have grown.

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

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

Governments are investing a lot of money to improve the situation. They purify sewage, build factories for breeding fish, despite these measures, it is necessary to limit the production of sturgeon.

In a dry and hot climate, a large amount of sea water evaporates, water molecules pass into the air. So, every year such a huge amount of water particles is carried away from the surface of the Caspian Sea that all together they would fill a bowl with a volume of several hundred cubic kilometers. This amount of water could fill ten such reservoirs, which will be Kuibyshev.

But can water from the sea surface get into the bottom layers of the Caspian, to a depth of 900-980 meters?

This is possible provided that the density of the surface layers of water is greater than the density of the bottom layers.

It is known that the density of sea water depends on salinity and temperature. The more salts the water contains, the denser it is, and therefore heavier. High temperature water is less dense than cold water. Only at low temperatures (about 0-4°C) is the reverse ratio given, when the water becomes denser as it heats up.

The high salinity of the surface layers of the sea is created in the hot season, when water evaporates strongly, while salt remains in the sea. At this time, the salinity of surface waters is not less, and even somewhat greater than the salinity of the deep and bottom layers.

The temperature of surface waters in the warm season is the same everywhere, about 25-28 °, that is, five times higher than at a depth of 150-200 meters. With the onset of the cold season, the temperature of the surface layers decreases and in a certain period it turns out to be 5-6° above zero.

The temperature of the near-bottom and deep (deeper than 150-200 m) layers of the Caspian Sea is the same (5-6 °), practically unchanged throughout the year.

Under these conditions, the lowering of denser surface cold and highly saline water into the bottom layers is possible.

Only in the southern regions of the Caspian, the temperature of surface water, as a rule, does not drop to 5-6°C even in winter. And, although the sinking of surface waters into the depths cannot occur directly in these areas, water is brought here by deep currents, which has descended from the surface in the more northern parts of the sea.

A similar phenomenon is observed in the eastern part of the border zone between the Middle and South Caspian, where cooled surface waters descend along the southern slope of the border underwater threshold and then follow the deep current to the southern regions of the sea.

Such widespread mixing of surface and deep waters is confirmed by the fact that oxygen has been found at all depths of the Caspian Sea.

Oxygen can get to the depths only with the surface layers of water, where it comes directly from the atmosphere or as a result of photosynthesis.

If there was no continuous supply of oxygen to the bottom layers, it would quickly be absorbed by animal organisms there or spent on the oxidation of the organic matter of the soil. Instead of oxygen, the bottom layers would be saturated with hydrogen sulfide, which is observed in the Black Sea. In it, the vertical circulation is so weak that oxygen in sufficient quantities does not reach the depth, where hydrogen sulfide is formed.

Although oxygen is found at all depths of the Caspian Sea, it is far from being in the same amount in different seasons of the year.

The water column is richest in oxygen in winter. The more severe the winter, that is, the lower the temperature on the surface, the more intense the aeration process, which reaches the deepest parts of the sea. Conversely, several warm winters in a row can cause the appearance of hydrogen sulfide in the bottom layers and even the complete disappearance of oxygen. But such phenomena are temporary and disappear in the first more or less severe winter.

The upper water column is especially rich in dissolved oxygen up to a depth of 100-150 meters. Here, the oxygen content ranges from 5 to 10 cubic meters. cm in litre. At depths of 150-450 m, oxygen is much less - from 5 to 2 cubic meters. cm in litre.

Deeper than 450 m there is very little oxygen and life is very poorly represented - several species of worms and mollusks, the smallest crustaceans.

Mixing of water masses is also caused by surge phenomena and waves.

Waves, currents, winter vertical circulation, surges, surges act constantly and are important factors in the mixing of waters. It is not surprising, therefore, that no matter where in the Caspian Sea we take a sample of water, everywhere its chemical composition will be constant. If there was no mixing of waters, all living organisms of great depths would die out. Life would be possible only in the zone of photosynthesis.

Where the waters mix well and this process proceeds quickly, for example, in shallow areas of the seas and oceans, life is richer.

The constancy of the salt composition of the water of the Caspian Sea is a common property of the waters of the World Ocean. But this does not mean that the chemical composition of the Caspian is the same as in the ocean or in any sea connected to the ocean. Consider a table showing the salt content in the waters of the ocean, the Caspian and the Volga.

The table shows that ocean water has very little in common with river water in terms of salt composition. In terms of salt composition, the Caspian Sea occupies an intermediate position between a river and an ocean, which is explained by the great influence of river runoff on the chemical composition of Caspian water. The ratio of salts dissolved in the water of the Aral Sea is closer to the salt composition of river water. This is understandable, since the ratio of the volume of river runoff to the volume of the waters of the Aral Sea is much larger than for the Caspian. A large amount of sulfate salts in the Caspian Sea gives its water a bitter-salty taste that distinguishes it from the waters of the oceans and the seas connected to them.

The salinity of the Caspian Sea is continuously increasing towards the south. In the pre-estuary space of the Volga, a kilogram of water contains hundredths of a gram of salts. In the eastern regions of the South and Middle Caspian, salinity reaches 13-14‰

The concentration of salts in the Caspian water is low. So, almost twenty times more salts can be dissolved in this water than there are in it.

B.A. Shlyamin. Caspian Sea. 1954

The coastline of the Caspian Sea is estimated at about 6500 - 6700 kilometers, with islands - up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low-lying and smooth. In the northern part, the coastline is indented by water streams and islands of the Volga and Ural deltas, the shores are low and swampy, and the water surface is covered with thickets in many places. The east coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding coasts are on the west coast in the area of ​​the Apsheron Peninsula and on the east coast in the area of ​​the Kazakh Gulf and Kara-Bogaz-Gol.

Peninsulas of the Caspian Sea

Large peninsulas of the Caspian Sea:
* Agrakhan Peninsula
* Absheron peninsula, located on the western coast of the Caspian Sea in the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, the cities of Baku and Sumgayit are located on its territory
* Buzachi
* Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory is the city of Aktau.
* Miankale
* Tub-Karagan

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

The largest islands:

* Ashur-Ada
* Garasu
* Gum
* Dash
* Zira (island)
* Zyanbil
* Kur Dasha
* Hara Zira
* Sengi-Mugan
* Chechen (island)
* Chygyl

Large bays of the Caspian Sea:

* Agrakhan Bay,
* Komsomolets (bay),
* Mangyshlak,
* Kazakh (bay),
* Turkmenbashi (Gulf) (former Krasnovodsk),
* Turkmen (bay),
* Gyzylagach,
* Astrakhan (Bay)
* Gyzlar
* Hyrcanus (former Astarabad) and
* Anzali (former Pahlavi).

Rivers flowing into the Caspian Sea

130 rivers flow into the Caspian Sea, of which 9 rivers have a mouth in the form of a delta. Large rivers flowing into the Caspian Sea are the Volga, Terek (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Samur (Russian border with Azerbaijan), Atrek (Turkmenistan) and others. The largest river flowing into the Caspian Sea is the Volga, its average annual runoff is 215-224 cubic kilometers. The Volga, Ural, Terek and Emba provide up to 88 - 90% of the annual drainage of the Caspian Sea.

Caspian Sea Basin

The area of ​​the Caspian Sea basin is approximately 3.1 - 3.5 million square kilometers, which is approximately 10 percent of the world's closed water basins. The length of the Caspian Sea basin from north to south is about 2,500 kilometers, from west to east - about 1,000 kilometers. The Caspian Sea basin covers 9 states - Azerbaijan, Armenia, Georgia, Iran, Kazakhstan, Russia, Uzbekistan, Turkey and Turkmenistan.

coastal states

The Caspian Sea washes the shores of five coastal states:
* Russia (Dagestan, Kalmykia and Astrakhan region) - in the west and north-west, the length of the coastline is 695 kilometers
* Kazakhstan - in the north, northeast and east, the length of the coastline is 2320 kilometers
* Turkmenistan - in the southeast, the length of the coastline is 1200 kilometers
* Iran - in the south, coastline length - 724 kilometers
* Azerbaijan - in the southwest, the length of the coastline is 955 kilometers

Cities on the coast of the Caspian Sea

The largest city - a port on the Caspian Sea - Baku, the capital of Azerbaijan, which is located in the southern part of the Absheron Peninsula and has 2,070 thousand people (2003). Other large Azerbaijani Caspian cities are Sumgayit, which is located in the northern part of the Absheron Peninsula, and Lankaran, which is located near the southern border of Azerbaijan. To the South-East of the Absheron Peninsula, there is a settlement of oil workers Neftyanye Kamni, whose facilities are located on artificial islands, overpasses and technological sites.

Large Russian cities - the capital of Dagestan Makhachkala and the southernmost city of Russia Derbent - are located on the western coast of the Caspian Sea. 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.

On the eastern shore of the Caspian Sea is the Kazakh city - the port of Aktau, in the north in the Ural delta, 20 km from the sea, the city of Atyrau is located, south of Kara-Bogaz-Gol on the northern shore of the Krasnovodsk Bay - the Turkmen city of Turkmenbashi, formerly Krasnovodsk. Several Caspian cities are located on the southern (Iranian) coast, the largest of them is Anzali.

Area, depth, volume of water

The area and volume of water in the Caspian Sea varies significantly depending on fluctuations in water levels. At a water level of -26.75 m, the area was approximately 392,600 square kilometers, the volume of water was 78,648 cubic kilometers, which is approximately 44 percent of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface level. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated from the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian Sea is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations

The water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past 3 thousand years, the amplitude of changes in the water level of the Caspian Sea has amounted to 15 meters. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuations have been carried out since 1837, during this time the highest water level was recorded in 1882 (-25.2 m.), the lowest - in 1977 (-29.0 m.) , since 1978 the water level has been rising and in 1995 it reached -26.7 m, since 1996 there has again been a downward trend in the level of the Caspian Sea. Scientists associate the causes of changes in the water level of the Caspian Sea with climatic, geological and anthropogenic factors.

Water temperature

The water temperature is subject to significant latitudinal changes, most pronounced in winter, when the temperature changes from 0-0.5 °C at the ice edge in the north of the sea to 10-11 °C in the south, i.e. the water temperature difference is about 10 °C. For shallow water areas with depths less than 25 m, the annual amplitude can reach 25-26 °C. On average, the water temperature near the western coast is 1-2 °C higher than that of the eastern one, and in the open sea the water temperature is 2-4 °C higher than near the coasts. By the nature of the horizontal structure of the temperature field in the annual cycle of variability, three time interval in the upper 2-meter layer. From October to March, the water temperature increases in the south and east, which is especially evident in the Middle Caspian. Two stable quasi-latitudinal zones can be distinguished, where the temperature gradients are elevated. This is, firstly, the border between the North and Middle Caspian, and, secondly, between the Middle and South. At the ice edge, in the northern frontal zone, the temperature in February-March increases from 0 to 5 °C, in the southern frontal zone, in the area of ​​the Apsheron threshold, from 7 to 10 °C. During this period, the least chilled waters are in the center of the South Caspian, which form a quasi-stationary core.

In April-May, the area of ​​minimum temperatures moves to the Middle Caspian, which is associated with faster warming of waters in the shallow northern part of the sea. True, at the beginning of the season in the northern part of the sea, a large amount of heat is spent on melting ice, but already in May the temperature rises here to 16-17 °C. In the middle part, the temperature at this time is 13-15 °C, and in the south it rises to 17-18 °C.

The spring warming of the water evens out the horizontal gradients, and the temperature difference between the coastal areas and the open sea does not exceed 0.5 °C. The heating of the surface layer, which begins in March, breaks the uniformity in the temperature distribution with depth. In June-September, horizontal uniformity is observed in the temperature distribution in the surface layer. In August, which is the month of the greatest warming, the water temperature throughout the sea is 24-26 °C, and in the southern regions it rises to 28 °C. In August, the water temperature in shallow bays, for example, in Krasnovodsk, can reach 32 °C. The main feature of the water temperature field at this time is upwelling. It is observed annually along the entire eastern coast of the Middle Caspian and partially penetrates even into the South Caspian.

The rise of cold deep waters occurs with varying intensity as a result of the influence of northwestern winds prevailing in the summer season. The wind of this direction causes the outflow of warm surface waters from the coast and the rise of colder waters from the intermediate layers. Upwelling starts in June, but it reaches its highest intensity in July-August. As a result, a decrease in temperature (7-15 °C) is observed on the surface of the water. Horizontal temperature gradients reach 2.3 °C at the surface and 4.2 °C at a depth of 20 m.

The center of upwelling is gradually shifting from 41-42° N. latitude in June, to 43-45 ° north. latitude in September. Summer upwelling is of great importance for the Caspian Sea, radically changing the dynamic processes in the deep water area. In the open areas of the sea, in late May - early June, the temperature jump layer begins to form, which is most pronounced in August. Most often, it is located between the horizons of 20 and 30 m in the middle part of the sea and 30 and 40 m in the southern part. Vertical temperature gradients in the shock layer are very significant and can reach several degrees per meter. In the middle part of the sea, due to the surge near the eastern coast, the shock layer rises close to the surface.

Since there is no stable baroclinic layer in the Caspian Sea with a large potential energy reserve similar to the main thermocline of the World Ocean, with the cessation of the effect of the prevailing winds that cause upwelling, and with the onset of autumn-winter convection in October-November, the temperature fields are rapidly reorganized to the winter regime. In the open sea, the water temperature in the surface layer drops in the middle part to 12-13 °C, in the southern part to 16-17 °C. In the vertical structure, the shock layer is washed out due to convective mixing and disappears by the end of November.

Water composition

The salt composition of the waters of the closed Caspian Sea differs from that of the ocean. There are significant differences in the ratios of the concentrations of salt-forming ions, especially for the waters of areas under the direct influence of continental runoff. The process of metamorphization of sea waters under the influence of continental runoff leads to a decrease in the relative content of chlorides in the total amount of salts of sea waters, an increase in the relative amount of carbonates, sulfates, calcium, which are the main components in the chemical composition of river waters. The most conservative ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ion. In the Caspian, the content of calcium and magnesium cations is almost two times higher than in the Sea of ​​Azov, and sulfate anion is three times higher. The salinity of the water changes especially sharply in the northern part of the sea: from 0.1 units. psu in the mouth areas of the Volga and Urals up to 10-11 units. psu on the border with the Middle Caspian.

Mineralization in shallow saline bays-kultuks can reach 60-100 g/kg. In the Northern Caspian, during the entire ice-free period from April to November, a quasi-latitudinal salinity front is observed. The greatest desalination associated with the spread of river runoff over the sea area is observed in June. The formation of the salinity field in the Northern Caspian is greatly influenced by the wind field. In the middle and southern parts of the sea, salinity fluctuations are small. Basically, it is 11.2-12.8 units. psu, increasing in the southern and eastern directions. Salinity increases insignificantly with depth (by 0.1–0.2 psu).

In the deep-water part of the Caspian Sea, in the vertical salinity profile, characteristic troughs of isohalines and local extrema are observed in the area of ​​the eastern continental slope, which indicate the processes of near-bottom creep of waters becoming saline in the eastern shallow waters of the South Caspian. The salinity value also strongly depends on the sea level and (which is interrelated) on the amount of continental runoff.

Bottom relief

The relief of the northern part of the Caspian is a shallow wavy plain with banks and accumulative islands, the average depth of the Northern Caspian is about 4-8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle. The Middle Caspian is quite deep, the depth of water in the Derbent depression reaches 788 meters. The Apsheron threshold separates the Middle and South Caspian. The South Caspian is considered deep water, the depth of water in the South Caspian depression reaches 1025 meters from the surface of the Caspian Sea. Shell sands are widespread on the Caspian shelf, deep-water areas are covered with silty sediments, and in some areas there is an outcrop of bedrock.

Climate

The climate of the Caspian Sea is continental in the northern part, temperate in the middle part and subtropical in the southern part. In winter, the average monthly temperature of the Caspian varies from -8 -10 in the northern part to +8-10 in the southern part, in summer - from +24-25 in the northern part to +26-27 in the southern part. The maximum temperature recorded on the east coast is 44 degrees.

The average annual rainfall is 200 millimeters per year, ranging from 90-100 millimeters in the arid eastern part to 1,700 millimeters off the southwestern subtropical coast. Evaporation of water from the surface of the Caspian Sea is about 1000 millimeters per year, the most intense evaporation in the area of ​​the Absheron Peninsula and in the eastern part of the South Caspian is up to 1400 millimeters per year.

Winds often blow on the territory of the Caspian Sea, their average annual speed is 3-7 meters per second, north winds prevail in the wind rose. In the autumn and winter months, the winds increase, the wind speed often reaches 35-40 meters per second. The most windy territories are the Apsheron Peninsula and the environs of Makhachkala - Derbent, where the highest wave was recorded - 11 meters.

currents

The circulation of water in the Caspian Sea is connected with the runoff and winds. Since most of the water flow falls on the Northern Caspian, northern currents predominate. An intense northern current carries water from the Northern Caspian along the western coast to the Absheron Peninsula, where the current is divided into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

Animal world

The fauna of the Caspian is represented by 1809 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian world, and most of the world's stocks of sturgeon are concentrated in it, as well as such freshwater fish as vobla, carp, pike perch. The Caspian Sea is the habitat of such fish as carp, mullet, sprat, kutum, bream, salmon, perch, pike. A marine mammal, the Caspian seal, also lives in the Caspian Sea. Since March 31, 2008, 363 dead seals have been found on the coast of the Caspian Sea in Kazakhstan.

Vegetable world

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

Origin of the Caspian Sea

The Caspian Sea is of oceanic origin - its bed is composed of oceanic-type earth's crust. It was formed about 10 million years ago, when the closed Sarmatian Sea, which lost contact with the world ocean about 70 million years ago, was divided into two parts - the "Caspian Sea" and the Black Sea.

Anthropological and cultural history of the Caspian Sea

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

Exploration of the Caspian Sea

The exploration of the Caspian Sea was started by Peter the Great, when, on his orders, an expedition was organized in 1714-1715 under the leadership of A. Bekovich-Cherkassky. In the 1820s, hydrographic studies were continued by I.F. Soyomov, and later by I.V. Tokmachev, M.I. Voinovich and other researchers. At the beginning of the 19th century, instrumental surveying of the coast was carried out by I.F. Kolodkin, in the middle of the 19th century. - instrumental geographic survey under the guidance of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary research on the hydrology and hydrobiology of the Caspian Sea has been carried out under the leadership of N. M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power in the Caspian Sea, geological research by I. M. Gubkin and other Soviet geologists was actively carried out, mainly aimed at finding oil, as well as research on the study of the water balance and fluctuations in the level of the Caspian Sea.

Mining of oil and gas

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

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

In addition to oil and gas production, salt, limestone, stone, sand, and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.

Shipping

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

Fishing and seafood

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 flourishes in the Caspian Sea.

Recreational resources

The natural environment of the Caspian coast with sandy beaches, mineral waters and therapeutic mud in the coastal zone creates good conditions for recreation and treatment. At the same time, in terms of the degree of development of resorts and the tourism industry, the Caspian coast noticeably loses 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.

Ecological problems

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

Border dispute over the status of the Caspian Sea

After the collapse of the USSR, the division of the Caspian Sea has long been and still remains the subject of unsettled disagreements related to the division of the resources of the Caspian shelf - oil and gas, as well as biological resources. For a long time there were negotiations 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 along one-fifth part between all the Caspian states. In 2003, Russia, Azerbaijan and Kazakhstan signed an agreement on the partial division of the Caspian Sea along the median line.

Coordinates: 42.622596 50.041848