I was resting somehow in the camp... It's no secret that almost every day contests are held there to entertain children and young people. So that's it. Was we have quiz. Question: "Which lake is the largest?" One guy, about fifteen years old, raised his hand first and answered: "Baikal". The strangest thing was that the answer was counted as correct! How so? Isn't the Caspian Sea the largest lake? Now I will explain to you.
How to tell the sea from the lake
I will list several signs by which a body of water is defined as a sea.
1. Rivers can flow into the sea.
2. The Outer Sea has direct access to the ocean.
3. If the sea is internal, then it is connected by straits with other seas or directly with the ocean.
Is the Caspian Sea suitable for the parameters of the sea
Need to check, does the Caspian Sea have signs of the sea. Into it really rivers flow, but they flow into many bodies of water: seas, lakes, oceans, and other rivers. The Caspian Sea is surrounded from all sides by land... Is it really inland sea? Then it must connect with the Black or Azov seas any strait. The strait too No... Exactly due to the lack of access to the World Ocean, the Caspian Sea is considered a lake.
"But why was it then called the sea, if it is a lake?"- you ask. Answer very simple: due to his large size and salinity... Indeed, The Caspian Sea is several times larger than the Azov Sea and is almost the same in size with the Baltic.
Fine! The problem with the quiz has been resolved. Judge for the soap !!!
Well then, i told, that the Caspian Sea in fact - Lake... Now I want to you provide small a selection of interesting facts about this lake.
1. The Caspian Sea is below sea level (-28 m), which once again proves that this is a lake.
2. BC near the lake lived nomadic Caspian tribes,in honor of which he was nicknamed the Caspian.
3. This the deepest enclosed body of water on the planet.
4. Many believe that the name of the group "Caspian Cargo" is related to the Caspian Sea... In some ways they are right ( No). Actually the expression "Caspian cargo" can mean any illegal cargo.
5.Caspian Sea OK suitable for tourism... Under the USSR, a large number of sanatoriums were built here. Today the same here you can see many hotels, water parks and beaches.
, Kazakhstan, Turkmenistan, Iran, Azerbaijan
Geographical position
Caspian Sea - view from space.
The Caspian Sea is located at the junction of two parts of the Eurasian continent - Europe and Asia. The length of the Caspian Sea from north to south is about 1200 kilometers (36 ° 34 "-47 ° 13" N), from west to east - from 195 to 435 kilometers, on average 310-320 kilometers (46 ° -56 ° c. d.).
The Caspian Sea is conventionally divided by physical and geographical conditions into 3 parts - the North Caspian, the Middle Caspian and the South Caspian. The conditional border between the North and Middle Caspian runs along the line about. Chechnya - Cape Tyub-Karagan, between the Middle and South Caspian - along the line of about. Residential - Cape Gan-Gulu. The area of the North, Middle and South Caspian is 25, 36, 39 percent, respectively.
Caspian Sea coast
Coast of the Caspian Sea in Turkmenistan
The territory adjacent to the Caspian Sea is called the Caspian region.
Peninsulas of the Caspian Sea
- Ashur-Ada
- Garasu
- Zyanbil
- Hara-Zira
- Sengi-Mugan
- Chygyl
Bays of the Caspian Sea
- Russia (Dagestan, Kalmykia and the Astrakhan region) - in the west and north-west, the length of the coastline is about 1930 kilometers
- Kazakhstan - in the north, north-east and east, the length of the coastline is about 2320 kilometers
- Turkmenistan - in the southeast, the length of the coastline is about 650 kilometers
- Iran - in the south, the length of the coastline is about 1000 kilometers
- Azerbaijan - in the southwest, the length of the coastline is about 800 kilometers
Cities on the coast of the Caspian Sea
On the Russian coast there are cities - Lagan, Makhachkala, Kaspiysk, Izberbash and the southernmost city of Russia Derbent. Astrakhan is also considered a port city of the Caspian Sea, which, however, is not located on the shores of the Caspian Sea, but in the Volga delta, 60 kilometers from the northern coast of the Caspian Sea.
Physiography
Area, depth, volume of water
The area and volume of water in the Caspian Sea varies significantly depending on fluctuations in the water level. With a water level of -26.75 m, the area is approximately 371,000 square kilometers, the volume of water is 78,648 cubic kilometers, which is approximately 44% of the world's lake water reserves. The maximum depth of the Caspian Sea is in the South Caspian depression, 1025 meters from its surface. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated according to the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.
Water level fluctuations
Vegetable world
The flora of the Caspian Sea and its coast is represented by 728 species. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, charovy and others, from flowering plants - zostera and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were introduced into the Caspian Sea by humans deliberately or on the bottoms of ships.
History of the Caspian Sea
Origin of the Caspian Sea
Anthropological and cultural history of the Caspian Sea
The finds in the Khuto cave off the southern coast of the Caspian Sea indicate that people lived in these parts about 75 thousand years ago. The first mentions of the Caspian Sea and tribes living on its coast are found at Herodotus. Approximately in the V-II centuries. BC NS. the tribes of the Saks lived on the coast of the Caspian. Later, during the period of the settlement of the Turks, during the IV-V centuries. n. NS. Talysh tribes (Talysh) lived here. According to ancient Armenian and Iranian manuscripts, Russians sailed in the Caspian Sea from the 9th-10th centuries.
Exploration of the Caspian Sea
The exploration of the Caspian Sea was started by Peter the Great, when, on his order, in 1714-1715, an expedition was organized under the leadership of A. Bekovich-Cherkassky. In the 1720s, hydrographic research was continued by the expedition of Karl von Verden and F.I.Soimonov, and later by I.V. Tokmachev, M.I.Voinovich and other researchers. At the beginning of the 19th century, instrumental survey of the banks was carried out by I.F.Kolodkin, in the middle of the 19th century. - instrumental geographic survey under the direction of N. A. Ivashintsev. Since 1866, for more than 50 years, expeditionary studies on the hydrology and hydrobiology of the Caspian have been conducted under the leadership of N.M. Knipovich. In 1897, the Astrakhan Research Station was founded. In the first decades of Soviet power in the Caspian Sea, geological research by I.M.Gubkin and other Soviet geologists was actively carried out, mainly aimed at finding oil, as well as research on the study of the water balance and fluctuations in the level of the Caspian Sea.
Economy of the Caspian Sea
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 oil and gas condensate resources are estimated at 18-20 billion tons.
Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf near Baku. In the second half of the 19th century, oil production began in industrial volumes on the Absheron Peninsula, then in other territories.
Shipping
Shipping is well developed in the Caspian Sea. Ferry services operate on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a navigable connection with the Sea of Azov through the Volga, Don and Volga-Don Canal.
Fishing and seafood production
Fishing (sturgeon, bream, carp, pike perch, sprat), caviar and seal fishing. More than 90 percent of the world's sturgeon catch is carried out in the Caspian Sea. In addition to industrial production, illegal production of sturgeon and their caviar is flourishing in the Caspian Sea.
Recreational resources
The natural environment of the Caspian coast with sandy beaches, mineral waters and curative mud in the coastal area creates good conditions for recreation and treatment. At the same time, in terms of the development of resorts and the tourism industry, the Caspian coast is noticeably inferior to the Black Sea coast of the Caucasus. At the same time, in recent years, the tourism industry has been actively developing on the coasts of Azerbaijan, Iran, Turkmenistan and Russian Dagestan. A resort area in the Baku region is actively developing in Azerbaijan. At the moment, a world-class resort has been created in Amburan, another modern tourist complex is being built in the area of the village of Nardaran, recreation in the sanatoriums of the villages of Bilgah and Zagulba is very popular. A resort area is also developing in Nabran, in the north of Azerbaijan. However, high prices, generally low level of service and lack of advertising lead to the fact that there are almost no foreign tourists in the Caspian resorts. The development of the tourism industry in Turkmenistan is hindered by a long-term policy of isolation, in Iran - by Sharia law, which makes it impossible for foreign tourists to spend mass vacations on the Caspian coast of Iran.
Ecological problems
Environmental problems of the Caspian Sea are associated with water pollution as a result of oil production and transportation on the continental shelf, the influx of pollutants from the Volga and other rivers flowing into the Caspian Sea, the vital activity of coastal cities, as well as flooding of certain objects due to the rise in the level of the Caspian Sea. Predatory hunting of sturgeon and their caviar, rampant poaching lead to a decrease in the number of sturgeons and to forced restrictions on their production and export.
International status of the Caspian Sea
Legal status of the Caspian Sea
After the collapse of the USSR, the division of the Caspian Sea for a long time was and still remains the subject of unresolved disagreements related to the division of the resources of the Caspian shelf - oil and gas, as well as biological resources. For a long time, negotiations were going on between the Caspian states on the status of the Caspian Sea - Azerbaijan, Kazakhstan and Turkmenistan insisted on dividing the Caspian along the median line, Iran - on dividing the Caspian Sea by one fifth between all the Caspian states.
With regard to the Caspian, the key is the physical and geographical circumstance that it is a closed inland water body that does not have a natural connection with the World Ocean. Accordingly, the norms and concepts of international maritime law should not be automatically applied to the Caspian Sea, in particular, the provisions of the 1982 UN Convention on the Law of the Sea. economic zone "," continental shelf ", etc.
The current legal regime of the Caspian Sea was established by the Soviet-Iranian treaties of 1921 and 1940. These treaties provide for freedom of navigation throughout the sea, freedom of fishing with the exception of ten-mile national fishing zones and a ban on ships flying the flag of non-Caspian states in its waters.
Negotiations on the legal status of the Caspian are currently ongoing.
Delimitation of sections of the seabed of the Caspian Sea for the purpose of subsoil use
The Russian Federation signed an agreement with Kazakhstan on delimiting the bottom of the northern part of the Caspian Sea in order to exercise sovereign rights to subsoil use (dated July 6, 1998 and the Protocol to it dated May 13, 2002), an agreement with Azerbaijan on delimiting adjacent sections of the bottom of the northern part of the Caspian Sea (dated September 23, 2002), as well as the trilateral Russian-Azerbaijani-Kazakh agreement on the junction point of the delimitation lines of adjacent sections of the seabed of the Caspian Sea (dated May 14, 2003), which established the geographic coordinates of the dividing lines delimiting the sections of the seabed, within which the parties exercise their sovereign rights in the field of exploration and production of mineral resources.
Caspian Sea is inland and is located in an extensive mainland depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows us to call it a lake, but it has all the features of the sea, since in past geological eras it had connections with the ocean.
Today Russia has access only to the North Caspian and the Dagestan part of the western coast of the Middle Caspian. The waters of the Caspian Sea wash the shores of countries such as Azerbaijan, Iran, Turkmenistan, Kazakhstan.
The sea area is 386.4 thousand km2, the volume of water is 78 thousand m3.
The Caspian Sea has a vast drainage basin, with an area of about 3.5 million km2. The nature of the landscapes, climatic conditions and types of rivers are different. Despite the vastness of the drainage basin, only 62.6% of its area is in wastewater areas; about 26.1% - for closed drainage. The area of the Caspian Sea itself is 11.3%. 130 rivers flow into it, but almost all of them are located in the north and west (and the eastern bank does not have a single river reaching the sea at all). The largest river in the Caspian basin is the Volga, which provides 78% of the river waters entering the sea (it should be noted that more than 25% of Russia's economy is located in the basin of this river, and this undoubtedly determines many hydrochemical and other features of the Caspian Sea waters), as well as rivers Kura, Zhaiyk (Ural), Terek, Sulak, Samur.
Physically and geographically and by the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional border between the northern and middle parts runs along the line of the Chechen island - the Tyub-Karagan cape, between the middle and the south - along the line of the Zhiloy island - Kuuli cape.
The shelf of the Caspian Sea is, on average, limited to a depth of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at a depth of 500–600 m, in the southern part, where it is very steep, at 700–750 m.
The northern part of the sea is shallow, its average depth is 5–6 m, maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom relief is complicated by the presence of banks, islands, grooves.
The middle part of the sea is a separate basin, the area of maximum depths of which - the Derbent depression - is shifted to the western coast. The average depth of this part of the sea is 190 m, the greatest is 788 m.
The southern part of the sea is separated from the middle Apsheron sill, which is a continuation of the Greater Caucasus. The depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian depression with a maximum depth of 1025 m for the sea is located east of the Kura delta. Several underwater ridges rise above the bottom of the basin, up to 500 m high.
The shores The Caspian Sea is diverse. In the northern part of the sea, they are rather strongly indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea - Tyuleniy, Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islets and channels, which often change their position. Many small islands and banks are located on other parts of the coastline.
The middle part of the sea has a relatively flat coastline. On the western coast, on the border with the southern part of the sea, the Absheron Peninsula is located. To the east of it are the islands and banks of the Apsheron archipelago, of which the largest is Zhiloy Island. The eastern coast of the Middle Caspian is more indented, here the Kazakh Gulf with Kenderli Bay and several capes stand out. The largest bay on this coast is Kara-Bogaz-Gol.
The islands of the Baku archipelago are located to the south of the Absheron Peninsula. The origin of these islands, as well as some banks off the eastern coast of the southern part of the sea, is associated with the activity of underwater mud volcanoes lying on the bottom of the sea. On the east coast there are large bays of Turkmenbashy and Turkmensky, and near the island of Ogurchinsky.
One of the most striking phenomena of the Caspian is the periodic variability of its level. In historical time, the Caspian Sea had a level lower than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) over the sea level, the amplitude of its fluctuations was almost 4 m, from –25.3 m in the eighties of the XIX century. to –29 m in 1977. In the last century, the level of the Caspian Sea changed significantly twice. In 1929, it stood at about –26 m, and since it was close to this mark for almost a century, this level position was considered to be a mean annual or secular level. In 1930, the level began to decline rapidly. By 1941, it had dropped by almost 2 m. This led to the drying up of vast coastal bottom areas. A decrease in the level, with its small fluctuations (short-term insignificant level rises in 1946-1948 and 1956-1958), continued until 1977 and reached -29.02 m, that is, the level took the lowest position in the last 200 years.
In 1978, contrary to all forecasts, the sea level began to rise. As of 1994, the level of the Caspian Sea was at –26.5 m, that is, in 16 years the level rose by more than 2 m. The rate of this rise is 15 cm per year. The increase in the level in some years was higher, and in 1991 it reached 39 cm.
The general fluctuations in the level of the Caspian Sea are superimposed on its seasonal changes, the mean multiyear of which reaches 40 cm, as well as on surges. The latter are especially pronounced in the Northern Caspian. The northwest coast is characterized by large surges created by the prevailing storms of the eastern and southeastern directions, especially during the cold season. A number of large (more than 1.5–3 m) surges have been observed here over the past decades. An especially large surge with catastrophic consequences was noted in 1952. Fluctuations in the level of the Caspian Sea cause great damage to the states surrounding its water area.
.gif) |
Climate. The Caspian Sea is located in temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since the sea stretches for almost 1200 km from north to south.
In the Caspian region, various systems of atmospheric circulation interact, however, during the year, the winds of the eastern points prevail (the influence of the Asian maximum). The position in rather low latitudes provides a positive balance of heat inflow, therefore the Caspian Sea serves as a source of heat and moisture for the passing air masses for most of the year. The average annual air temperature in the northern part of the sea is 8–10 ° С, in the middle - 11–14 ° С, in the southern part - 15–17 ° С. However, in the northernmost regions of the sea, the average January temperature is from –7 to –10 ° С, and the minimum during the invasions of the Arctic air is up to –30 ° С, which determines the formation of the ice cover. In summer, the entire region under consideration is dominated by rather high temperatures - 24–26 ° С. Thus, the North Caspian is subject to the sharpest temperature fluctuations.
The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, and most of it falls on the cold season of the year (from October to March). However, the North Caspian Sea differs in this respect from the rest of the basin: here the average annual precipitation is less (for the western part, only 137 mm), and the seasonal distribution is more even (10–18 mm per month). In general, we can talk about the closeness of climatic conditions to arid ones.
Water temperature. Distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, the nature of the bottom topography, isolation) have a certain impact on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be regarded as homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and South Caspian, surface and deep masses can be distinguished, separated by a transitional layer. In the North Caspian and in the surface layers of the Middle and South Caspian, the water temperature varies over a wide range. In winter, temperatures change from north to south from less than 2 to 10 ° С, the water temperature near the western coast is 1–2 ° С higher than that of the east, in the open sea the temperature is higher than at the coasts: by 2–3 ° С in the middle part and by 3–4 ° С in the southern part of the sea. In winter, the temperature distribution is more uniform with depth, which is facilitated by the winter vertical circulation. In moderate and severe winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing point.
In summer, the temperature changes in space from 20 to 28 ° C. The highest temperatures are observed in the southern part of the sea, and temperatures are also quite high in the well-warmed shallow North Caspian. The zone of distribution of the lowest temperatures is adjacent to the eastern coast. This is due to the rise of cold deep waters to the surface. Temperatures are also relatively low in the poorly warmed deep-water central part. In the open areas of the sea, in late May – early June, a layer of temperature jump begins, 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. In the middle part of the sea, due to the drive off the east coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature throughout the year is about 4.5 ° C in the middle and 5.8–5.9 ° C in the southern part.
Salinity. Salinity values are determined by factors such as river runoff, water dynamics, which mainly includes wind and gradient currents, the resulting water exchange between the western and eastern parts of the North Caspian and between the North and Middle Caspian, bottom topography, which determines the location of waters with different salinity, mainly along the isobaths, evaporation, providing a shortage of fresh water and the inflow of more saline waters. These factors collectively affect seasonal differences in salinity.
The North Caspian can be considered as a reservoir of constant mixing of river and Caspian waters. The most active mixing occurs in the western part, where both river and middle Caspian waters directly flow. In this case, horizontal salinity gradients can reach 1 ‰ per 1 km.
The eastern part of the North Caspian is characterized by a more uniform salinity field, since most of the river and sea (Middle Caspian) waters enter this sea area in a transformed form.
According to the values of the horizontal salinity gradients, it is possible to distinguish in the western part of the North Caspian a river-sea contact zone with water salinity from 2 to 10 ‰, in the eastern part from 2 to 6 ‰.
Significant vertical salinity gradients in the North Caspian are formed as a result of the interaction of river and sea waters, with runoff playing a decisive role. The intensification of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated water arriving in summer from the seaside is 10–15 ° C higher than that of the bottom water.
In the deep-water basins of the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5 ‰. The greatest difference between the maximum and minimum salinity was noted in the area of the Absheron sill, where it is 1.6 ‰ in the surface layer and 2.1 ‰ at the 5 m horizon.
The decrease in salinity along the western coast of the South Caspian in the 0–20 m layer is caused by the Kura river runoff. The influence of the Kura runoff decreases with depth; at the depths of 40–70 m, the range of salinity fluctuations is no more than 1.1 ‰. Along the entire western coast to the Absheron Peninsula, there is a strip of desalinated waters with a salinity of 10–12.5 ‰ coming from the North Caspian.
In addition, in the South Caspian, an increase in salinity occurs when saline waters are carried out from bays and bays on the eastern shelf under the influence of southeastern winds. Subsequently, these waters are transferred to the Middle Caspian.
In the deep layers of the Middle and South Caspian, salinity is about 13 ‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep-water part of the South Caspian, the upper boundary of waters with increased salinity drops to 250 m. It is obvious that in these parts of the sea, vertical mixing of waters is difficult.
Surface water circulation. The currents in the sea are mainly wind-driven. In the western part of the Northern Caspian, the currents of the western and eastern quarters are most often observed, in the eastern - southwestern and southern ones. The currents caused by the runoff of the Volga and Ural rivers are traced only within the estuarine seashore. The prevailing current velocities are 10–15 cm / s, in the open regions of the Northern Caspian the maximum velocities are about 30 cm / s.
In the coastal areas of the middle and southern parts of the sea, in accordance with the wind directions, currents of the north-west, north, south-east and south directions are observed, along the east coast currents of the east direction often take place. Along the western coast of the middle part of the sea, the most stable currents are southeastern and southern. The velocities of the currents are on average about 20–40 cm / s, the maximum ones reach 50–80 cm / s. Other types of currents also play a significant role in the circulation of sea waters: gradient, seiche, inertial.
Ice formation. The North Caspian is covered with ice annually in November, the area of the freezing part of the water area depends on the severity of winter: in severe winters, the entire North Caspian is covered with ice, in soft ice it is kept within the 2-3 meter isobath. The appearance of ice in the middle and southern parts of the sea occurs in December-January. On the east coast, ice is of local origin, on the west coast - most often brought from the northern part of the sea. In severe winters near the eastern coast of the middle part of the sea, shallow bays freeze, near the coast, coastlines and fast ice form, near the western coast, drifting ice in abnormally cold winters extends to the Absheron Peninsula. The disappearance of the ice cover is observed in the second half of February – March.
|
Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of regularities. The central part of the Northern Caspian is characterized by a fairly uniform oxygen distribution. An increased oxygen content is found in the areas of the pre-estuarine seashore of the Volga River, a lower one - in the southwestern part of the North Caspian. In the Middle and South Caspian, the highest oxygen concentrations are confined to coastal shallow areas and pre-estuarine coastal areas of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.). In summer, due to significant heating of water masses and activation of photosynthesis processes, the leading factors in the formation of oxygen regime in surface waters are photosynthetic processes, in bottom waters - biochemical oxygen consumption by bottom sediments. Owing to the high temperature of the waters, the stratification of the water column, the large influx of organic matter and its intense oxidation, oxygen is rapidly consumed with a minimum supply to the lower layers of the sea, as a result of which an oxygen deficiency zone forms in the North Caspian. Intensive photosynthesis in the open waters of the deep-water regions of the Middle and South Caspian covers the upper 25-meter layer, where oxygen saturation is more than 120%. |
- The North Caspian, which is a vast area of mixing of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
- in the Middle Caspian, the cyclonic nature of the circulation contributes to the rise of deep waters with a high content of nutrients into the overlying layers of the sea;
- in the deep-water areas of the Middle and South Caspian, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.
On the dynamics of concentrations nutrients During the year, the Caspian Sea is influenced by such factors as seasonal fluctuations in biogenic runoff in the sea, seasonal ratio of production and destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter in the North Caspian, processes of winter vertical circulation in deep-water areas seas.
In winter, a significant water area of the Northern Caspian is covered with ice, but biochemical processes are actively developing in sub-ice water and ice. The ice of the North Caspian, being a kind of accumulator of nutrients, transforms these substances entering the sea with river runoff and from the atmosphere.
As a result of the winter vertical circulation of waters in the deep-water regions of the Middle and South Caspian in the cold season, the active layer of the sea is enriched with nutrients due to their supply from the underlying layers.
Spring for the waters of the Northern Caspian is characterized by a minimum content of phosphates, nitrites and silicon, which is explained by the spring outbreak of phytoplankton development (silicon is actively consumed by diatoms). High concentrations of ammonium and nitrate nitrogen, characteristic of the waters of a large area of the Northern Caspian during floods, are due to intensive washing by the river waters of the Volga delta.
.gif)
In the spring season, in the area of water exchange between the North and Middle Caspian in the subsurface layer, at the maximum oxygen content, the phosphate content is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.
In the South Caspian, the distribution of nutrients in spring is basically similar to their distribution in the Middle Caspian.
In summer, in the waters of the Northern Caspian, a redistribution of various forms of biogenic compounds is found. Here, the content of ammonium nitrogen and nitrates significantly decreases, at the same time there is a slight increase in the concentration of phosphates and nitrites and a rather significant increase in the concentration of silicon. In the Middle and South Caspian, the concentration of phosphates decreased due to their consumption in the process of photosynthesis and the difficulty of water exchange with the deep-water accumulation zone.
In autumn in the Caspian Sea, due to the cessation of the activity of some types of phytoplankton, the content of phosphates and nitrates increases, and the concentration of silicon decreases, as there is an autumn outbreak of the development of diatoms.
More than 150 years on the shelf of the Caspian Sea oil.
Currently, large reserves of hydrocarbons are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons of oil equivalent (of which 132 million tons of oil and 78 billion cubic meters of gas), on the shelf of the North Caspian - 1 billion tons of oil ...
In total, about 2 billion tons of oil have already been produced in the Caspian Sea.
Losses of oil and products of its processing during extraction, transportation and use reach 2% of the total volume.
Main sources of income pollutants, including oil products, into the Caspian Sea - this is the outflow with river runoff, the discharge of untreated industrial and agricultural wastewater, municipal wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, transportation of oil by sea. Places of entry of pollutants with river runoff are 90% concentrated in the Northern Caspian, industrial effluents are mainly confined to the area of the Apsheron Peninsula, and increased oil pollution of the South Caspian is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud volcanism) in the zone of oil and gas structures.
From the territory of Russia, about 55 thousand tons of oil products are annually supplied to the North Caspian, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.
Thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange, threatens the death of the hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg / l, for phytoplankton - 0.1 mg / l.
The development of oil and gas resources of the bottom of the Caspian Sea, the projected reserves of which are estimated at 12-15 billion tons of standard fuel, in the coming decades will become the main factor of anthropogenic pressure on the ecosystem of the sea.
.gif)
Caspian autochthonous fauna. The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, molluscs, etc.
Arctic species. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire fauna of the Caspian Sea (mysids, sea cockroach, white fish, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna is made up of crustaceans (71.4%), which easily tolerate desalination and live at great depths of the Middle and South Caspian (from 200 to 700 m), since the lowest water temperatures are kept here throughout the year (4.9– 5.9 ° C).
.gif)
Mediterranean views. These are 2 types of mollusks, needle-fish, etc. At the beginning of the 20s of our century, the mithielastr mollusk penetrated here, later 2 types of shrimp (with mullet, when acclimatized), 2 types of mullet and flounder. Some Mediterranean species entered the Caspian after the opening of the Volga-Don Canal. Mediterranean species play a significant role in the food supply for fish in the Caspian Sea.
Freshwater fauna(228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, carp, as well as rotifers).
Marine species. These are ciliates (386 forms), 2 types of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropods (74 species and subspecies), bivalve molluscs (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most peculiar brackish water bodies of the planet.
The Caspian Sea provides over 80% of the world's sturgeon catches, the bulk of which is in the North Caspian.
To increase catches of sturgeon, which sharply decreased during the years of falling sea level, a set of measures is being carried out. Among them is a complete ban on fishing for sturgeon in the sea and its regulation in rivers, an increase in the scale of factory sturgeon breeding.
.gif) |
The length of 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 and smooth. In the northern part, the coastline is cut by water channels 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 eastern coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding shores are on the western coast in the area of the Absheron Peninsula and on the eastern coast in the area of the Kazakh Bay and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian region.
One of the brightest bodies of water in the world is the Caspian Lake, which is located at the junction of Asia and Europe, and its shores and waters belong to 5 countries. The Caspian Sea is an attractive and inexpensive place for recreation and treatment. The beautiful nature and the early opening of the swimming seasons make the rest on the Caspian coast more tempting.
Caspian Lake is the largest of all lakes on the planet. It is often referred to as the Caspian Sea because of its impressive size and slightly salty water. It is located at the junction of Asia and Europe on the territory of 5 countries: Turkmenistan, Kazakhstan, the Russian Federation, Azerbaijan and Iran.
Despite the fact that the tourist infrastructure is inferior to the Black Sea in terms of development, the Caspian coast is in demand among tourists. This is facilitated by the rapid warming up of the reservoir due to its shallow depth, often the swimming season can begin at the end of April and end in October. The average water temperature in summer is 20-22 ° C.
Benefits of relaxing on the Caspian Lake:
- clean sea sand;
- picturesque nature;
- healing sea climate;
- mineral springs;
- healing mud;
- the presence of sanatoriums of various orientations;
- excellent fishing, especially in Astrakhan;
- active entertainment for every taste (diving, rafting, windsurfing, etc.);
- low cost for housing and entertainment with a developed infrastructure;
- being on the territory of the Russian Federation, which saves a lot of time on paperwork;
- great service;
- warm water for six months;
- the opportunity to save more than one thousand rubles on vacation, housing and meals without denying yourself anything.
You can get to the Caspian Sea in various ways, but it is worth deciding in the area of which coastal city to plan a vacation.
There are several resort towns on the Caspian Lake in the Russian Federation:
Astrakhan is very popular among fishermen and lovers of outdoor activities related to water, because in its vicinity there are many rivers, and the Caspian Lake is within easy reach - an hour by car.
The ancient city of Derbent also enjoys special love among tourists, because it is surrounded by such sights as picturesque mountains, ancient fossils and legendary caves overgrown with legends, and other interesting places to visit.
Such Dagestan resort towns as Izberbash, Kaspiysk, Makhachkala and Kalmyk Lagan are also not deprived of attention. A lot of tourists come to the Caspian Lake and stay in Azerbaijani cities (Baku, Lankaran, Sumgait), Turkmen resort Turkmenbashi and Avaza, Kazakhstani Aktau and Atyrau.
The origin of the Caspian lake and its name
More than 5 million years ago, the ancient sea was split into several smaller ones, including the Caspian Sea and the Black Sea. After this separation, the reservoirs were repeatedly merged into a single whole and split up, but about 1.75-2 million years ago the reservoir was finally cut off from the waters of the World Ocean.
The current name of the Caspian Lake is new. And according to one of the hypotheses, it came from the name of the Caspian tribe, who lived in its southwest in the first millennium BC. 
Throughout the entire period of its existence, the Caspian Lake possessed more than 70 different names among different peoples of tribes, including:
- Abeskunskoe - by the name of the island and the city, which were located before their flooding by a reservoir in the XIV century in the low-lying plain formed by the Kura Kura River.
- Saraiskoe.
- Khazar or Mazandaran - Iranian name in honor of the province of the same name, located on the coast, is used in Iran to this day.
- Dzhurdzhanskoe (Girkanskoe) - the ancient Greek name of the reservoir, originated from the region of Girkania and the city of Gorgan, now belonging to Iran.
- Derbentskoe - after the name of the ancient coastal town of the same name in Dagestan.
- Sihai.
- Khvali is an ancient Russian name derived from the name of the Khvalis people who lived in the north of the Caspian.
Exploration and development of the Caspian lake
Finds on the western coast of Dagestan indicate that people lived in this area already 2 million ago. At the confluence of the river. Darvagchay (Dagestan) excavated remains at sites older than 600 thousand years. Excavations on the southern coast indicate that people lived in this area 75 thousand years ago. All these studies show that the climate and living conditions were suitable for humans.
The founder of geography and writer Hecateus of Miletus (VI-V century BC) in his work "Land Description" described the Caspian Sea as the Hyrcanian Sea. In the 5th century BC, the ancient Greek historian was one of the first to suggest that the Caspian is not connected with other seas or the ocean, although the scientists of those times argued that the reservoir is the northern bay of the World Ocean, which washed all the known lands.
Aristotle in the IV century BC was sure that the Hyrcanian reservoir was connected by groundwater with the Black Sea. The study of the relationship of the Caspian Sea with other large bodies of water was carried out by the Macedonian during his travels. In 323 BC, he sent a sailor and geographer Patroclus to explore the shores of the Caspian. 
The navigator reached the Kara-Bogaz Bay and considered it a river that connects the Caspian Lake with the ocean. The famous ancient Greek geographer and historian Strabon in one of his 17 chronicles (books) "Geography" presented the Caspian Lake stretched in an east-west direction.
Arab scientists of the 9th-13th centuries made their significant contribution to the exploration of the Caspian, recording in their works information about coastal cities and states, islands, flowing rivers and oil, which was extracted in Azerbaijan (Baku).
Expansion of the geography of trade relations allowed European, Persian and Turkish travelers to receive a lot of information about the Caspian Sea. And the eminent Marco Polo (XIII century) also described a huge reservoir.
A very detailed, although in some places erroneous, map of the Caspian was compiled in the 17th century by the famous scientist and traveler, the German Adam Olearius. Peter I repeatedly traveled towards the Caspian Lake, and on the basis of the data provided by him, Russian hydrographers compiled very detailed maps of the Caspian.
Since the 17th century, the exploration of the Caspian and its coastal environs has become systematic and versatile. Peter the Great in 1714 sent a research expedition under the command of Bekovich-Cherkassky. A few years later, the research was continued by Verdun and Soimonov, a little later by Tokmachev, Voinovich and other scientists.
At the beginning of the 19th century, the instrumental survey of the coast was carried out by I.F. Kolodkin, several decades later, the geographical survey was carried out by an expedition led by N.A. For half a century, starting in 1866, regular expeditions of hydrological and hydrobiological orientation were carried out under the leadership of N.M. Knipovich.
The first years of Soviet rule, the Caspian was actively explored by geologists, mainly in search of oil deposits, the study of the water balance and fluctuations in the height of the water in the lake.
History of the Caspian Lake
The Caspian Lake is located on the site of one of the gigantic reservoirs of antiquity. The origin of the Caspian Lake is inextricably linked with the ancient sea of Tetris, which more than 50-55 million years ago united the Pacific and Atlantic oceans, being in the territory of the present Caspian Sea, Azov, Black and Mediterranean seas. 
After long and complex tectonic movements, Tetris was first cut off from the Pacific Ocean, and a little later from the Atlantic.
About 5-6.5 million years ago, the gigantic body of water broke into shallow basins, which included the Caspian Sea and the Black Sea.
After that, they repeatedly united and moved apart.
1.8-2 million years ago, the Caspian Sea was finally cut off from the waters of the World Ocean, and it is this time that is considered the beginning of its origin.
Throughout its history, the lake has repeatedly changed its coastline until it acquired its current appearance.
Physical and geographical characteristics of the Caspian lake
The water surface of the lake is noticeably below the level of the World Ocean and is -27.5 ... -28.5 m. The Caspian Sea area varies depending on the level and water and is within 380-390 km2, the total volume is 73.7-74.1 km3 ...
The Caspian is territorially subdivided into several parts with its own characteristics:
- North Caspian- 24% of the total area of the reservoir falls on it. This part is shallow, and its average depth does not exceed 6 m, the maximum reaches 25 m, the volume of water is less than 1%.
- Middle Caspian- 36% of the entire area of the lake falls on it. This part of the lake is a kind of basin with a maximum depth of almost 800 m, and an average depth of 190 m. It contains a third of the total volume of water.
- South Caspian- occupies 40% of the total area of the lake and it accounts for the deepest part of the reservoir. It contains 2/3 of the volume of all water - 66%. The average depth is 340 m, and the deepest depression is 1025 m.
The length of the coastline reaches almost 7 thousand km. The maximum length of the lake is slightly more than 1,000 km, and the widest point is 435 km. The minimum width is considered to be a segment of 195 km. The average width is considered to be 317 km.
Depth map of the Caspian lake The shores vary greatly in their landscape. The northern coast is gently sloping and low, around it there is a semi-desert in the lowlands, and a desert on an elevation. The southern coastal area is partly low and partly mountainous and consists of the Elbrus ridge. The mountains of the Caucasus come close to the western part.
The eastern coastline is a desert and semi-desert limestone plateau. The shape of the coast changes greatly depending on the water level, which periodically fluctuates.
Climate
The Caspian water temperature fluctuates significantly depending on latitude. This amplitude is most noticeable in winter, when the water under the ice in the northern part has a temperature of 0, -0.5 ° C above zero, in the south at this time it is 10-11 ° C.
According to averaged data, the temperature in the western part of the lake is up to 2 ° C higher than in the eastern one, and with distance from the coast, it rises by 2-4 ° C compared to the coastal zone. In summer, the water in the lake warms up to 23-29 ° C, and in shallow waters in the northern part it can reach 34-40 ° C. Deeper than 100 m, the temperature stabilizes and is 4-7 ° C.
The Caspian Lake is located in three climatic zones: continental (north of the reservoir), temperate (middle) and subtropical (South Caspian). In winter, the average temperature ranges from -8 to -11 ° С in the north and up to +8 to +11 ° С in the south of the lake.
In summer, the northern part warms up to 24-25 ° С with a positive mark, in the south the temperature rises to 26-27 ° С. The highest temperature +44 ° С was recorded in the east of the reservoir. 
The average amount of precipitation per year is about 200 mm. Moreover, on the arid eastern coast, at least 90-100 mm falls, in the south-west these figures can reach 1700 mm. The average annual wind speed is in the range of 3-8 m / s, mainly winds from the north prevail. In autumn and winter, their speed increases and can reach 35-39 m / s.
When in the northern part of the lake the thermometer shows large minus values, trees and flowers bloom on the southern coast. In winter, the surface of the lake is unstable, storm winds prevail. In winter, only the northern shallow water freezes; in severe winter frosts, the North Caspian and the coastal waters of the Middle Caspian are covered with ice.
Flora and fauna
The flora of the Caspian Sea and its coastal environs is more than 720 plant species. The lake is mainly dominated by algae (diatoms, brown, etc.), from angiosperms - rupee and zostera. Most of the vegetation of the Caspian Lake comes from the Neogene period, but some got into the reservoir on the bottoms of ships or deliberately, with the help of humans.
Among the animals of the Caspian and its environs, there are more than 1,800 species, of which more than 400 are vertebrates, and more than 90 species are fish (sturgeon, carp, bream, mullet, beluga, etc.). Mammals are represented only by the Caspian seal, which is the smallest of the seal family and lives exclusively in the Caspian Lake.
The lake is home to the largest flock of sturgeon in the world, and a lot of pike perch, carp and roach live in the waters of the sea. Up to 80% of the total volume of the world catch of sturgeon and more than 90% of the world fishery of black caviar falls on the Caspian Lake.
The main migration route of birds between Europe and Asia passes over the Caspian Sea (in the spring - in the south, and in the fall - in the north). During seasonal migrations, over 11.5 million birds fly over the lake, about 5 million individuals remain for the winter. The lake itself is home to over 850 species of animals, of which almost 80 are vertebrates. There are more than 500 species of plants in the lake.
Islands
There are more than 50 large and medium-sized islands in the Caspian Lake with a total area of about 350 sq. km. 
| State that owns the island | Island name |
| Azerbaijan | Jasper |
| Oil Rocks | |
| Pelican | |
| Zenbil | |
| Sengi Mugan | |
| Boyuk-Zira | |
| Baku archipelago | |
| Kichik Zira | |
| Kurinsky | |
| Chilov | |
| Ignat dashi | |
| Inner Stone | |
| Harya Zira | |
| Kara Su | |
| Dash Zira | |
| Novoivanovsky | |
| Chikil | |
| Kurinskaya spit | |
| Gil | |
| Baburiy | |
| Iran | Ashur-Ada |
| Kazakhstan | Seal Islands |
| Average | |
| Südev | |
| Konevsky Oseryodok | |
| Somyonok | |
| Babiy | |
| Somovy | |
| Turkmenistan | Ogurchinsky |
| Bolshoi Syudostinsky | |
| Marine Ivan-Karaul | |
| Clean Banks | |
| Small Syudostinsky | |
| Birdie | |
| Egg | |
| Small Setnoy | |
| Jumpers | |
| Sandy | |
| Bazaar | |
| Konevsky | |
| Green | |
| Marine Privet | |
| Batkachny | |
| Nordic | |
| Small Pearl | |
| Big Setnoy | |
| Blinov | |
| Verkhniy Oseedok | |
| Khokhlatsky | |
| Südev | |
| Lower | |
| Small | |
| Likhachev | |
| Seal | |
| Seventh | |
| Marine Chapura | |
| Chechen |
Flowing rivers
More than 130 rivers flow into the Caspian, of which 9 differ in delta-shaped mouths. 95% of the water comes to the Caspian from the rivers. Most of them flow into the lake in the northern and western parts of the reservoir, in the east there are no rivers flowing into it.
The largest and most significant rivers of the Caspian basin:
Roughly 88% of the total runoff falls on rivers such as the Volga, Terek, Ural and Emba, which flow into the north of the Caspian. 7% of the runoff falls on such rivers as the Kura, Sulak, Samur and others, smaller, flowing into the western part of the Caspian. The Iranian part of the reservoir receives about 5% of the runoff of the Sefidrud, Heraz and Gorgan rivers.
Ecological state
The state of the Caspian Lake and adjacent territories is a source of concern to ecologists.
The main causes of environmental problems are associated with humans and their activities:
- extraction and transportation of oil and gas products;
- inflow of pollutants from river runoff waters;
- poaching;
- waste from coastal cities;
- rapid jumps in the water level in the Caspian Sea due to irrigation of lands by the waters of rivers flowing in and the use of hydroelectric power plants.
How the Caspian Lake is used
The Caspian Lake has been actively used by humans for many centuries.
Main directions of economic activity:
Recreational resources of the Caspian lake
The climate and nature of the Caspian coast with its clean sand beaches, healing mud and healing springs provide great potential and excellent conditions for sanatorium treatment and tourist recreation.
The development of resort and tourist infrastructure, although noticeably inferior to a similar industry on the Black Sea coast, is actively expanding and improving the quality of service. The most noticeable burst of development in recent years has been observed in the Republic of Dagestan, Iran, Turkmenistan and Azerbaijan. 
Rest on the coast of the Caspian Sea in the Russian Federation and the former CIS countries is notable for its low cost and, on average, in quality in some places is inferior to that on the Black Sea, but in actively developing places the level is quite high.
Popular recreation areas with developed infrastructure:
- Baku;
- Amburan;
- Makhachkala;
- Bilgah;
- Derbent.
- Type;
- Lankaran;
- Nardaran.
The development of the Turkmen resort and tourism industry is hampered by internal policies that isolate the state from most tourists. And in Iran, mass recreation is difficult because of the harsh Sharia law.
There are 3 protected areas on the coast:
The Caspian Lake is located at the junction of Europe and Asia and is the largest lake in the world.
There are many interesting facts about the reservoir:
- Its size is larger than Japan, but smaller in area than Germany.
- In terms of depth, the Caspian Sea is in third place, second only to Tanganyika and Baikal.
- Every 2.5 centuries, a complete renewal of the waters takes place.
- On the Iranian coast, an albino beluga is caught, whose caviar is the most expensive in the world. It has a white tint and is packaged in unusual cans made of real gold.
- The largest beluga weighed over 1200 kg and was caught in the 1920s. XX century on the Russian coast. In terms of its dimensions, it is comparable to a great shark.
- Throughout the history of the lake, it has had more than 70 different names.
- Scientists are still debating whether to consider the Caspian Lake as a sea, justifying this by the fact that its area exceeds the size of some seas, and the bottom is created according to the oceanic type. But at the same time, the body of water is closed and does not connect with the ocean and other seas.
- The smallest coastline of the five countries belongs to the Russian Federation.
- More than 80% of water flows into the lake from the river. Volga.
The Caspian Lake is rich in flora and fauna, it is distinguished by warm waters, a long bathing season. It is best known for its depth and size, production of oil, gas and sturgeon, the reserves of which exceed those known throughout the world.
The lake is 95% supplied with runoff water to the rivers. On its coast there are many resorts and sanatoriums, whose attractiveness can be assessed, and at affordable prices.
Article design: Mila Friedan
Video about the Caspian Sea
Film about the Caspian Sea:
Natural World Heritage Sites of South America Campos Cerrado National Parks: Chapada dos Veadeyrus and Emas, Brazil
Is there a sea in finland
The meaning of the eighth wonder of the world in a reference book on phraseology
Federal system of reconnaissance and airspace control
Federal system of reconnaissance and airspace control problems of improvement