Southern coast of the Caspian Sea. Caspian Sea (lake): rest, photo and map, shores and countries where the Caspian Sea is located. Rest on the Caspian Sea

Caspian Sea - the largest lake on Earth, an endless lake, located at the junction of Europe and Asia, called the sea because of its size, and also because its bed is composed of an oceanic type of crust. The water in the Caspian is salty, - from 0.05 ‰ near the mouth of the Volga to 11-13 ‰ in the southeast. The water level is subject to fluctuations, according to 2009 data was 27.16 m below sea level. The area of ​​the Caspian Sea is currently about 371,000 km², the maximum depth is 1025 m.

Geographical position

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 Sea is 25, 36, 39 percent, respectively.

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.

Peninsulas of the Caspian Sea

Major peninsulas of the Caspian Sea:

• Agrakhan Peninsula
• Absheron Peninsula, located on the western coast of the Caspian Sea on the territory of Azerbaijan, at the northeastern end of the Greater Caucasus, on its territory are the cities of Baku and Sumgait
• Buzachi
• Mangyshlak, located on the eastern coast of the Caspian Sea, on the territory of Kazakhstan, on its territory there is the city of Aktau
• Miancale
• Tyub-Karagan

Islands of the Caspian Sea

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

• Ashur-Ada
• Garasu
• Boyuk-Zira
• Zyanbil
• Kur Dashi
• Hara-Zira
• Ogurchinsky
• Sengi-Mugan
• Seal
• Seal Islands
• Chechen
• Chygyl

Bays of the Caspian Sea

Large bays of the Caspian Sea:

• Agrakhan Gulf
• Kizlyar Bay
• Dead Kultuk (former Komsomolets, former Gulf of Tsesarevich)
• Kaydak
• Mangyshlak
• Kazakh
• Kenderli
• Turkmenbashi (bay) (former Krasnovodsk)
• Turkmen (bay)
• Gizilagach (former Kirov Bay)
• Astrakhan (bay)
• Hasan-kuli
• Gyzlar
• Hyrcanus (formerly Astarabad)
• Anzali (formerly Pahlavi)
• Kara-Bogaz-Gol

Rivers flowing into the Caspian Sea- 130 rivers flow into the Caspian Sea, of which 9 rivers have delta-shaped estuaries. Large rivers flowing into the Caspian Sea are Volga, Terek, Sulak, Samur (Russia), Ural, Emba (Kazakhstan), Kura (Azerbaijan), Atrek (Turkmenistan), Sefidrud (Iran) 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, Sulak and Emba provide up to 88-90% of the annual runoff into 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 above its surface. In terms of maximum depth, the Caspian Sea is second only to Baikal (1620 m) and Tanganyika (1435 m). The average depth of the Caspian Sea, calculated according to the bathygraphic curve, is 208 meters. At the same time, the northern part of the Caspian is shallow, its maximum depth does not exceed 25 meters, and the average depth is 4 meters.

Water level fluctuations- the water level in the Caspian Sea is subject to significant fluctuations. According to modern science, over the past three thousand years, the magnitude of the change in the water level of the Caspian Sea has reached 15 meters. According to archeology and written sources, a high level of the Caspian Sea is recorded at the beginning of the XIV century. Instrumental measurement of the level of the Caspian Sea and systematic observations of its fluctuation 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), with In 1978, the water level increased and in 1995 reached the level of -26.7 m; since 1996, a downward trend has been observed again. Scientists associate the reasons for the change in the water level of the Caspian Sea with climatic, geological and anthropogenic factors. But in 2001, the sea level began to rise again, and reached -26.3 m.

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, that is, the difference in water temperature is about 10 ° C. For shallow areas with depths less than 25 m, the annual amplitude can reach 25-26 ° C. On average, the water temperature is west coast 1-2 ° C higher than in the east, and in the open sea the water temperature is 2-4 ° C higher than near the coast.

Water composition- the salt composition of the waters of the enclosed 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 conserved ions are potassium, sodium, chlorine and magnesium. The least conservative are calcium and bicarbonate ions. In the Caspian, the content of calcium and magnesium cations is almost two times higher than in the Sea of ​​Azov, and the content of sulfate anions is three times higher.

Bottom relief- the relief of the northern part of the Caspian is a shallow undulating plain with banks and accumulative islands, the average depth of the North Caspian is 4-8 meters, the maximum depth does not exceed 25 meters. The Mangyshlak sill separates the North Caspian from the Middle. The Middle Caspian is quite deep, the water depth in the Derbent depression reaches 788 meters. The Absheron sill separates the Middle and South Caspian. The South Caspian Sea is considered to be 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, in some areas there is an outcrop of bedrocks.

Climate- The climate of the Caspian Sea is continental in the northern part, temperate in the middle and subtropical in the southern part. In winter, the average monthly air temperature 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 of +44 degrees was recorded on the east coast. Average annual rainfall is 200 millimeters, 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 - 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 - up to 1400 millimeters per year. The average annual wind speed is 3-7 meters per second, northern winds prevail in the wind rose. In the autumn and winter months, the winds increase, the speed of the winds often reaches 35-40 meters per second. The most windy areas are the Apsheron Peninsula, the vicinity of Makhachkala and Derbent, where the highest wave with a height of 11 meters was also recorded.

Currents- the circulation of waters in the Caspian Sea is associated with runoff and winds. Since most of the runoff is in the North Caspian, northern currents prevail. The intense northern current carries water from the North Caspian along the western coast to the Absheron Peninsula, where the current splits into two branches, one of which moves further along the western coast, the other goes to the Eastern Caspian.

Economic development of the Caspian Sea

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, and then in other territories. In 1949, at Oil Rocks, for the first time, they began to extract oil from the bottom of the Caspian Sea. So, on August 24 this year, Mikhail Kaverochkin's team began drilling a well, which gave the long-awaited oil on November 7 of the same year. 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 well developed in the Caspian Sea. Ferry services operate on the Caspian Sea, in particular, Baku - Turkmenbashi, Baku - Aktau, Makhachkala - Aktau. The Caspian Sea has a shipping connection with Sea of ​​Azov across the Volga, Don and Volga-Don canal.

Fishing and seafood production-fishing (sturgeon, bream, carp, pike perch, sprat), caviar production, as well as 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.

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

Caspian Sea Is a unique ecological system. It is the largest lake on planet Earth. The diverse biosphere, beautiful nature and richness of natural resources make it attractive in all aspects.

Caspian Sea: description, photo and video

Many people wonder what is the area of ​​the Caspian Sea. It is rather difficult to answer this question, since this parameter changes depending on the seasonality. For example, when the level of the water surface is at around 27 meters, then the reservoir covers an area of ​​370 thousand square kilometers. This is almost 45 percent of the volume of freshwater lakes on Earth.

The Caspian also has a heterogeneous depth. In the north, the maximum depth of the Caspian Sea only about 25 meters, and the average is within 4 meters. The southern region, on the contrary, is very deep - 1025 kilometers. This is the third indicator in the world among lakes, after Tanganyika and. Scientists cannot yet name the exact reasons for such fluctuations in the Caspian Sea. Among the most probable versions is climate and crustal change in the region.

Caspian Sea - Azerbaijan (Baku)

Since the lake is not only an industrial reservoir, but also a recreational one, the water temperature in the Caspian Sea is also of great interest. In winter, the lake experiences significant temperature fluctuations. On the southern side, it is kept at around 11 degrees, and on the northern side it can drop to 0.5 and below. Sometimes glaciation can be observed in this region.

In the summer period, which lasts here from early June to mid-September, the temperature is approximately the same throughout the reservoir. In the upper layers, the average values ​​are kept within the range of 26-27 degrees, and in shallow water, the reservoir can heat up to 32. The water is slightly salted, but the saturation depends on the regional factor and can vary. The largest concentration is in the west and south, and in the northern part, thanks to freshwater rivers, it is the smallest. The local climate is also changeable.

The lake is located in three climatic zones at once:

• continental;
• moderate;
• subtropical.

Summers in the region are quite hot. The thermometer can reach up to 44 degrees Celsius. In winter, in the south, these indicators fluctuate up to +10, and in the north - up to -10. The Caspian Sea on the map has quite flat shores, but in fact, its borders are very indented by river estuaries, peninsulas and straits. The length of the coast, including the islands, is 7 thousand kilometers. In the north, the coast is low-lying, and there is a widespread swampy area caused by channels. In the east, limestones are widespread, flowing into semi-deserts.

There are about 50 islands in the lake. The biggest ones are:

• Seals;
• Boyuk-Zira;
• Chechnya;
• Ogurchinsky;
• Ashur-Ada.

Among the numerous bays, Kara-Bogaz-Gol can be noted. Until the end of the 19th century, it was a kind of lagoon, but in 1980, the construction of a dam began here, because of this, the amount of water entering the lake decreased. To date, the strait has been restored.

What rivers flow into the Caspian Sea? The lake feeds a large number of rivers, the largest of which are:

• Volga;
• Sulak (Pro);
• Terek;
• Ural (Pro).

Every year they bring hundreds of cubic meters of fresh water to the lake.

The region has been actively developed for many centuries. Today, there are large ports on the Caspian Sea that connect trade routes. Of the Russian ones, the most important are Astrakhan and Makhachkala. Oil production is also carried out in the Caspian Sea. According to experts, the region's oil resources amount to about 10 billion tons. There are also gas reserves here.

The Caspian Lake is a great place to relax. Local beaches amaze everyone who comes here. The quality of recreation on the Caspian Sea is in no way inferior. A pleasant climate, comfortable beaches and fresh air - the Caspian Sea is ready to give all this to tourists. Those who decide to visit the Caspian Sea are able to pleasantly surprise the prices for vacations. For a low cost, you can get high quality service.

Among the cities that are popular are the following Caspian Sea resorts:

• Makhachkala;
• Kaspiysk;
• Astrakhan;
• Lagan;
• Derbent;
• Dagestan lights.

Derbent is very attractive from a historical point of view. Astrakhan allows you to enjoy active rest and fishing, and Makhachkala attracts with comfortable and well-equipped beaches. Rest on the Caspian Sea in Russia allows you to restore health and relax from the bustle of the city. Among the foreign resorts, the most popular are Baku (Azerbaijan), Avaza (Turkmenistan) and Aktau.

Caspian Sea on the map

Where is the Caspian Sea? It is spread over the continent of Eurasia. It is interesting that its eastern coast is located in Asia, and the western one in Europe. Conventionally, the sea is divided into several parts:

• North Caspian;
• South Caspian;
• Middle Caspian.

Of these, only the North Caspian is a sea shelf. It contains only 1 percent of the total water volume and ends at the Chechen Island, located near the Kizlyar Bay.

Which countries is washed by the Caspian Sea? There are 5 states on the shore of the lake:

• Azerbaijan;
• Iran;
• Turkmenistan;
• Kazakhstan;
• Russia.

The largest coastline runs through the territory of Kazakhstan, in second place, according to this indicator, is Russia. The coast of Azerbaijan has the smallest length, but it is he who owns the largest port - Baku.

There are also other large settlements on the coast of the salt reservoir:

• Anzali (Iran) - 111 thousand people;
• Aktau (Kazakhstan) - 178 thousand people;
• Atyrau (Russia) - 183 thousand people

Astrakhan also belongs to the coastal cities of the Caspian, although the city is located 69 kilometers from the coast. Other Russian cities on the seashore include Makhachkala, Derbent and Kaspiysk.

Caspian Sea or Lake?

The Caspian Sea is a geographical feature, the essence of which is not entirely correlated with its name.

Why is the Caspian Sea considered a lake? Caspian Sea is a closed and closed reservoir. It receives water from rivers, has no connection with the oceans and other seas. The water here, although salty, is much lower than that of other seas. International maritime laws do not apply to the Caspian Sea.

On the other hand, the Caspian Sea is quite large in size, which differs from the traditional ideas about lakes. Even Baikal, and even more so, is inferior to it in area. There are no other lakes in the world whose coastline simultaneously belongs to five states. The bottom structure is also very similar to the oceanic type. With a high degree of probability, the waters of the Caspian Sea flowed into the Mediterranean Sea many centuries ago, but due to drying out and tectonic processes, they were separated.

The Caspian Sea is rich in islands, the size of which, even by international standards, is quite large.

The nature of the Caspian Sea

One of the most interesting mysteries of the Caspian Sea is the habitation of a population of seals on the territory of the lake, which are a small species of those that live in the cold northern waters. However, their appearance on the coast at least indicates that the local places are beginning to recover from the ecological point of view after the negative consequences of oil production.

Vegetable and animal world The Caspian Sea is very diverse. The underwater ecosystem boasts a large number of crustaceans, molluscs, gobies, herring and sprat. Many species are endemic, meaning they live only in this region and nowhere else.

Freshwater species also live in the waters of the lake. They were able to adapt to salt water. These are primarily carp and perch fish. At the end of the Ice Age, Arctic fish and invertebrates entered the area. In the 40s of the last century, the waters of the Caspian were deliberately inhabited by mullet, nereis and abra, which are a forage base for sturgeon.

Fish processing plants operate in the vicinity of the Caspian Sea, as well as purification stations designed to ensure water circulation cycles. Also, systematic work is underway to breed many varieties of underwater abodes of industrial value. The region is of great interest for fishing tourism. This vacation is especially popular in the Astrakhan region on the Caspian Sea.

The flora of the lake is represented by over 700 plant species. Some of them grow on land, others in water. The phytoplankton of the Caspian Sea consists of both marine and freshwater algae. According to rough estimates, about 440 species of algae live in the reservoir.

Historical facts

The Caspian coast was once home to ancient civilization, which subsequently disappeared. There is an opinion that in the vicinity of Dagestan, the waters hide from human eyes Itil - the capital city of the Khazar Kaganate, which completely disappeared in the 12th century. In Derbent, there is still a wall from the ancient settlement that goes to a depth of 300 meters. For what purposes it was built and who built it is a mystery.

Another interesting feature of the Caspian Sea is the Sabail citadel, located under water in the Baku Bay. The building was flooded in an earthquake in 1306. In 1723, the upper part of the tallest tower became visible above the water surface - this was a consequence of a decrease in the water level. Today the fortress is again hidden in the depths of the Caspian, although in sunny weather it can be seen in the water column.

The territory of the Caspian Sea was a bone of contention between the neighboring countries. Disputes over the allocation of property and resources of the lake have been going on for 22 years. In 2018, countries finally came to a common denominator. On August 12, the Convention on the Legal Status of the Caspian Sea was signed. Prior to this, in the legal field, regulation was carried out on the basis of the Soviet-Iranian agreements, defining the Caspian as a closed reservoir, and each border state had an independent right to a 10-mile zone. The rest of the lake was divided equally.

How the Caspian Sea was divided? The new agreement gives each state 15 miles of territorial sea. Also, the bottom of the Caspian Sea is divided into sectors, as is the case with the seas, and the sovereignty of the water column is established according to the principle of a lake.

For the current day Caspian Sea is an economically important region. Without it, it is impossible to imagine Eurasia, including Russia. Everyone should visit the Caspian Sea, and the protection of the reservoir should be carried out at the state level. Only through joint efforts can this natural pearl be preserved.

The Caspian Sea is a residual (relict) reservoir of the much more extensive Khvalynsky Sea, which once occupied the entire Caspian lowland. In the era of the Khvalynskaya transgression, when the level of the Caspian Sea was much higher than the present one, it was connected to the Black Sea through a strait that passed on the site of the Kumo-Manych lowland. The modern Caspian Sea is the largest lake in the world, only for its size ranked among the seas. Its water surface area is 424,000 km 2. The sea level dropped after the ice age and now lies 28 m below sea level.

Geographic location of the Caspian Sea. Extended Map

The huge basin of the Caspian Sea is morphologically subdivided into three parts:
1) northern- shallow water (less than 10 m), separated from the middle part by a line passing from the mouth of the Terek to the Mangyshlak peninsula,
2) average- with an average depth of 200 m and the greatest at 790 m and
3) southern- the deepest, with the greatest depth up to 980 m and with an average of 325 m.
Deep depressions in the middle and southern parts of the sea are separated by an underwater sill extending from the Apsheron Peninsula to Krasnovodsk.

Water balance of the Caspian Sea

The bays of the Caspian Sea - Kaidak, Komsomolets and Kara-Bogaz-Gol - are shallow. The first two have now dried up and turned into litter due to the lowering of the sea level. The Gulf of Kara-Bogaz-Gol, in essence, is a huge shallow (up to 10 m deep) independent lake, equal in area to Lake Ladoga. The salinity of the Caspian Sea is relatively low, on average about 12.6 ° / oo, which is about 3 times less than the salinity of the world's oceans.

A large number of tributaries flow into the Caspian Sea: the Volga, Ural, Terek, Kura, etc. The Volga is of primary importance for it, delivering about 80% of the total annual inflow into the sea, equal to about 325 km 3. All this huge mass of water entering the sea evaporates from its surface into the atmosphere. The Caspian Sea is considered to be closed, but this is not entirely true. In fact, it has a constant flow into the Kara-Bogaz-Gol Bay, the level of which is 0.5-1.0 m below the level of the Caspian Sea. Kara-Bogaz-Gol is separated from the sea by a narrow sand spit, leaving a strait up to 200 m wide in places. Through this strait, water flows from the Caspian Sea into the gulf (on average over 20 / km 3 per year), which, thus, plays the role of a giant evaporator. The water in the Kara-Bogaz-Gol Bay reaches extremely high salinity (169 ° / oo).

Kara-Bogaz-Gol is of great importance for the chemical industry. It is literally an inexhaustible source for the extraction of mirabilite. In relation to the Caspian Sea, Kara-Bogaz-Gol plays an important role as a kind of desalination plant. If there were no runoff from the sea to Kara-Bogaz-Gol, its salinity would increase. Table 1 shows the water balance of the Caspian Sea according to the data of B. D. Zaikov.

Table 1. Water balance of the Caspian Sea

Rivers carry out a huge amount of sandy-silty sediments into the Caspian Sea. The Volga, Terek and Kura annually bring about 88 million tons of sediment. Approximately the same amount (71 million tons) comes in the form of a runoff of chemically dissolved substances.

More or less constant currents with a general counterclockwise direction are observed in the Caspian Sea. In summer, the waters of the Caspian Sea are very hot, and the water temperature at the surface reaches 25-27 ° (see Fig. 84). In winter, the sea slowly cools down and for the most part retains a positive temperature (1 °). Only its shallow northern part freezes, where floating ice appears annually and an ice cover is established. There are no ice phenomena in the middle and southern parts of the sea.

The Caspian Sea is one of the seas where tidal currents are not observed. Water level fluctuations are relatively small. If we take into account the historical data, then the long-term amplitude of the level fluctuations can be taken equal to 5 m. The low standing of the sea level in the past is evidenced by the ruins of a caravanserai located under water in the area of ​​Baku, as well as a number of other historical data.

Lowering the level of the Caspian Sea

At the very beginning of the 19th century, the sea level was very high and reached 700 cm.Then, starting in 1930, over 15 years (from 1930 to 1945), the sea level fell by almost 2 m, As a result, its water surface area decreased almost 20,000 km2. The shallow bays Kaydak and Komsomolets dried up and turned into litters, and in some places the modern sea retreated by 10 km or more. The lowering of the level caused great complications in the operation of the ports of the Caspian coast and sharply worsened the conditions of navigation, especially in the North Caspian. In this regard, the problem of the level of the Caspian Sea in the 20th century has attracted a lot of attention.

There are two points of view on the reasons for the decrease in the level of the Caspian Sea. According to one of them, the lowering of the level is explained by geological factors, i.e., the slow subsidence of the coast and the entire basin taking place. In favor of this view, the well-known facts of the lowering of the sea shores in the region of Baku and in other places are cited. Supporters of another, hydrometeorological point of view (B. A. Apollon, B. D. Zaikov and others) see the main reason for the decrease in sea level in the change in the ratio of the elements of the water balance. As BD Zaikov has shown, the drop in the level of the Caspian Sea is connected and explained by the exceptional low water content of the Volga in 1930-1945; its runoff was significantly below the norm. As for the influence of epeirogenic fluctuations on the level of the Caspian Sea, their role, apparently, is very insignificant, since the magnitude of the ongoing lowering of the coast and bottom of the sea is calculated in millimeters.

The pearl of unique beauty and originality is the Caspian Sea. It is a unique, the world's only closed body of water with a fragile and priceless ecosystem. Its uniqueness is attracting worldwide attention. The Caspian Sea is considered the largest inland body of water in the world, located at the junction of Asia and Europe. Poets, philosophers, historians, geographers devoted a lot of their works to this amazing natural creation. Among them: Homer, Herodotus, Aristotle. The biological environment of the Caspian Sea is also unique. But first things first. We invite you to find out about the depth, level, location of this reservoir, which countries are washed by the Caspian Sea. Well, let's go ...

Historical references

Many are interested in where the Caspian Sea is located, the history of its origin. But few people know that it is of oceanic origin. Thirteen million years ago, this place was the bottom of the ocean. As a result of natural disasters, the Alps arose and disconnected the Sarmatian Sea from the Mediterranean. 5 million years passed, and the Sarmatian Sea was divided into smaller bodies of water, which included the Black and Caspian Seas. The connection and separation of waters continued for a long time. And now, 2 million years ago, the Caspian was completely cut off from the World Ocean. This was the beginning of its formation. History confirms that during the period of formation, the depth, the area of ​​the Caspian Sea has repeatedly changed.

Today the Caspian is classified as the largest closed lake. Due to its enormous size, it is commonly called the sea. And also due to the fact that it was formed on the earth's crust of the oceanic type.

Today the Caspian Sea accounts for 44% of the planet's lake waters. Throughout its formation, different tribes and peoples gave the lake about 70 names. The Greeks called it the Hyrcanian (Djurdjanian) lake from the name of the city of Gorgan and the province of Hyrcania. The ancient Russians called it the Khvalynsk Sea, from the name of the Khvalis people who lived on the coast. Arabs, Persians, Azerbaijanis, Turks, Crimean Tatars called it the Khazar Sea. Once upon a time in the delta of the Kura River, which flows into a reservoir, there was an island and a city, after which it was called the Abeskun Sea. Later this city was flooded. There was also the name of Saraiskoye Lake. In honor of the city of Derbant (Dagestan), it was named the Derbent Sea. There was also the name Sihai et al.

Geographic location

Many people want to know where the Caspian Sea is located on the map. This place is located at the junction of Europe and Asia. The physical and geographical conditions of the sea make it possible to divide it into three parts:

1. The share of the Northern Caspian is 25% of the reservoir.
2. The Middle Caspian zone has 36%.
3. The component of the southern part of the lake is 39%.

The North and Middle Caspian Sea separates the Chechen island with the Tyub-Karagan cape. The Middle and South Caspian Sea divides Chilov Island with Cape Gan-Gulu.

The territory adjacent to the lake is called the Caspian region. The dimensions of the Caspian Sea are amazing. The coastline stretches for about 6,500 - 6,700 kilometers. The shores are low and smooth in structure. The northern part of the coastline is cut by water channels and islands of the Ural and Volga deltas. The shores are mostly low and swampy, covered with thickets. The east coast has a limestone structure. In the west, the shores are very winding.

Relief and depth, area of ​​the Caspian Sea

These rates are constantly fluctuating. As a result, they affect sea level. The Caspian Sea thus changes the area and volume of water. If its level is 26.75 km, then the area is 371,000 km 2. What are the maximum and average depths of the Caspian Sea? In terms of maximum depth, it is second only to Baikal and Tanganyika. The maximum depth in the South Caspian depression is 1,025 m. The bathygraphic curve helps to calculate the average depth of the Caspian, which indicates a depth of 208 m. In the north, the reservoir is shallower - 25 m. The Middle Caspian has many deep depressions, continental slopes, and shelves. Here the average depth reaches 192 m.The Derbent depression is 788 m deep.

The length of the lake from north to south is 1,200 km, and the width of the Caspian Sea from west to east is up to 435 km. The relief of the northern part of the lake is flat, with accumulative islands and banks. The southern part of the Caspian shelf is rich in shell sands, deep-water areas with silty sediments. Sometimes bedrocks appear here.

Peninsulas, islands and bays of the Caspian

A number of large peninsulas are located in the area of ​​the Caspian Sea. On the western coast, near Azerbaijan, there is the Absheron Peninsula. It is here that the cities of Baku and Sumgait are located. On the eastern side (the territory of Kazakhstan) is the Mangyshlak peninsula. The city of Aktau was built here. It is also worth noting the following large peninsulas: Miankale, Tyub-Karagan, Buzachi, Agrakhan peninsula.

The total area of ​​the large and medium-sized islands of the Caspian Sea is 350 km 2. There are about 50 such islets. The largest and most famous are: Ashur-Ada, Garasu, Chechen, Chigil, Gum, Dash-Zira, Ogurchinsky, etc.

Such a huge body of water cannot exist without bays. There are known Agrakhan, Kizlyar, Mangyshlak, Kazakh bays. It is also worth remembering the Kaydak Bay, Kenderli, Turkmen, Astrakhan, Hasan-Kuli, Anzeli.

The salt lake Kara-Bogaz-Gol is considered a special bay-lagoon of the Caspian Sea. In 1980, a dam was built, which separates this strait from the Caspian Sea. Every year, 8-10 km 3 of water flows from the Caspian to Kara-Bogaz-Gol.

Which countries is washed by the Caspian?

The Intergovernmental Economic Conference of the Caspian states established that five coastal countries are washed by the Caspian Sea. Which ones? In the north, north-east and east, it borders on Kazakhstan. The coastline is 2,320 km. Who does the Caspian Sea border with in the south? This is Iran with shores 724 km away. Turkmenistan is located in the southeast with a coastline of about 1,200 km. The northwest and west of the Caspian Sea is occupied by Russia with a length of 695 km. Azerbaijan stretches for 955 km in the southwest. This is a kind of "Caspian Five".

Coastline and nearby towns

Many cities, ports and resorts are located on the Caspian Sea. In Russia, the largest objects are considered: Kaspiysk, Makhachkala, Izberbash, Lagan, Dagestanskie Ogni, Derbent. Astrakhan is the largest port city in the Caspian Sea, located in the Volga delta (60 km from the northern coast).

Baku is considered the largest port city in Azerbaijan. Its location is in the southern part of the Absheron Peninsula. The city is home to 2.5 million people. Sumgait is located a little in the north. Lankaran is located near the southern border of Azerbaijan. In the southeast of the Apsheron Peninsula, there is a village of oil workers - Oil Rocks.

In Turkmenistan, on the northern shore of the Krasnovodsk Bay, there is the city of Turkmenbashi. Avaza is a large resort in this country.

The port city of Aktau was built in Kazakhstan near the Caspian Sea. To the north, in the delta of the Ural River, there is Atyrau. In Iran, on the southern coast of the reservoir, Bandar Anzali is located.

Rivers flowing into the Caspian Sea

130 large and small rivers flow into the Caspian. Nine of them have a deltoid mouth. Among the largest rivers, we single out the Volga, Ural, Terek, Samur, Sulak, Embu, Kura, Atrek. The Volga is considered the largest river flowing into the reservoir. For a year, on average, 215-224 km 3 of water flows out of it. All of the above rivers replenish the annual water supply of the Caspian by 88-90%.

Currents, flora and fauna of the Caspian

For those who are interested in where the Caspian Sea flows, the answer is already clear - it is a closed body of water. The water circulates in it thanks to the winds and drains. Most of the water flows into the North Caspian, therefore the northern currents circulate there. These intense currents carry water to the western coast of the Absheron Peninsula. There the current passes into two branches - one moves parallel to the western bank, the other to the eastern one.

The fauna of the Caspian basin is represented by 1810 animal species. 415 of them are vertebrates. About 100 species of fish swim in the Caspian Sea, and a large number of sturgeons also live here. Freshwater fish are also found here, represented by pike perch, carp, roach. There are also a lot of carp, mullet, sprat, kutum, bream, salmon, perch, pike in the sea. It is worth remembering another inhabitant - the Caspian seal.

The flora of the Caspian Sea and the coastal zone numbers 730 species. It is important to note that the reservoir is overgrown with blue-green, diatomaceous, red, brown, charovy algae. The most common are the flowering algae - ruppia and zostera. The age of the Caspian flora belongs to the Neogene period. Many plants entered the Caspian Sea by means of ships or conscious human actions.

Research work

Between 285 and 282 BC. the Greek king Seleukos I ordered the geographer Patroclus the Macedonian to explore the Caspian Lake. Later, this work was continued by order of Peter the Great. For this purpose, an expedition was specially organized, led by A. Bekovich-Cherkassky. Later, the research was continued by the expedition of Karl von Werden. The following scientists were also involved in the study of the Caspian: F.I. Simonov, I.V. Tokmachev, M.I. Voinovich.

At the end of the 19th century, instrumental coastal survey was carried out by I.F. Kolodkin, later - N.A. Ivashentsev. During the same period, N.M. studied the hydrology and hydrobiology of the Caspian for 50 years. Knipovich. 1897 was marked by the founding of the Astrakhan Research Station. At the beginning of the Soviet era, the Caspian Sea was studied by I.M. Gubkin and other geologists. They directed their work to the search for oil, the study of the aquatic environment, changes in the level of the Caspian Sea.

Economic sector, shipping, fishing

Many deposits of gas and oil have been found in the Caspian. Scientists have proved that the oil resources here are about 10 billion tons, and together with gas condensate - 20 billion tons. As early as 1820, oil production began on the Absheron shelf, near Baku. Then oil production on an industrial scale began to be dealt with in other regions. Oil production from the bottom of the Caspian Sea began in 1949, at Oil Rocks. The long-awaited oil well was drilled by Mikhail Kaverochkin. In addition to oil and gas, salt, limestone, stone, sand, and clay are mined in the Caspian.

They also pay enough attention to shipping. Ferry crossings operate constantly. The most famous directions: Baku - Aktau, Makhachkala - Aktau, Baku - Turkmenbashi. Through the Don, Volga and Volga-Don canal, the Caspian Lake is connected with the Azov Sea.

Local residents catch sturgeon, bream, carp, pike perch, sprat in the waters of the sea. They are engaged in seal hunting and caviar hunting. Unfortunately, in this reservoir you can also come across illegal sturgeon fishing and caviar extraction. The flounder, mullet, and various types of shrimp caught here are popular. Sturgeon fish feed here on the nereis worm, which was specially brought to the Caspian Sea. The "five" countries of the Caspian Sea, washed by its waters, specially organize fish breeding and spawning farms.

In the northern shallow waters of sturgeon most of all, especially near Russia. It is worth listing the sterlet, beluga, sturgeon, thorn, stellate sturgeon living there. Many people like to catch carp species: bream, roach, asp. There are many catfish, grass carp, silver carp living here. There are more small inhabitants in the Caspian than large ones. Herring winters and spawns in the south of the lake. Fishing in the Caspian Sea is allowed all year round, except April - May. They are allowed to use fishing rods, spinning rods, donuts and other devices.

Most of all for fishing in Russia the Astrakhan region is chosen. The catch of some sturgeon is temporarily prohibited here, but you can catch pike, catfish, pike perch. In spring, sabrefish and rudd often bite here. In Kalmykia, industrial fishing is carried out in Lagan. Large specimens of carp are found here. Fishermen often have to spend the night in boats. The water in these areas is very clear, therefore spearfishing is used.

Rest on the Caspian Sea

Sandy beaches, mineral waters, curative mud of the Caspian coast are a good help for treatment and recreation. The tourist industry and resorts are not as developed here as on the Black Sea, but there are many who want to relax. It is at a fairly popular level in Azerbaijan, Turkmenistan, Iran and Russian Dagestan. Azerbaijan has developed a resort area near Baku. Only locals rest here, foreign tourists lack a sufficient level of service and good advertising.

The Russian coast is mainly located in Dagestan. Potential tourists are afraid to go here. But the beauty of the Caspian is simply mesmerizing! It is here that you can admire the waves with gray scallops, the bitter salinity of the dark water, and small seashells on the shore. Rest on the Caspian Sea is often considered exotic. It's more of a lake ...

The increased salinity of water in the Caspian Sea increases it medicinal properties... The water in the reservoir warms up early, so you can safely come here in May. In September, you can have a great time, because the water is kept at + 21 ° C.

What are the conditions for recreation in Dagestan near the sea? Here the coast is covered with yellow velvety sea sand. The water of the Caspian Sea warms up faster than in the Black Sea, because the former is much shallower. The swimming season starts here in mid-May. The beauty of the Caspian coast is complemented by picturesque mountains, which are not far from Derbent. Here you can admire the oldest marine fossils, which were raised by gas formation to a height of thousands of meters. After that, many caves were formed here, about which various legends go. Many locals come to these places to worship the higher powers.

During the Soviet period, Dagestan was a holiday destination for tourists from different parts of the USSR. Rest here is cheaper than on the Black Sea coast, the sea is warmer and the sandy coast is more pleasant.

The Caspian coast in Dagestan has many kilometers of beaches: Makhachkala, Samursky, Manas, Kayakentsky. On their territory there are recreation centers (150 units), boarding houses, sanatoriums, children's camps. You can order rooms not only in state hotels, boarding houses, but also in large, small private hotels. To rent a single room here costs from 500 to 1,000 rubles, a double room - 700-1,500 rubles, luxury apartments - 1,500-2,000 rubles.

If you get tired of swimming in the sea, then in Dagestan you can go to the peaks covered with snow caps. Rafting enthusiasts can go to the fast mountain rivers. Tour guides offer interesting excursions to historical sites.

Not far from the Caspian coast, it is worth seeing the capital of Dagestan - Makhachkala. This beautiful and well-equipped city has a highly developed infrastructure. Makhachkala residents are trying to attract as many tourists as possible to their city and are building the resort area "Cote d'Azur". This building occupies 300 hectares of area.

The South Dagestan coast with the center in Derbent is the most attractive place for tourism. This area has a temperate continental climate, located in the subtropics. The area is rich in citrus fruits, figs, pomegranates, almonds, walnuts, grapes and other crops.

The no less colorful city of Izberbash. Here there is beautiful nature with clean mountain-sea air, saturated with the aroma of forests that grow low on the foothills of the Greater Caucasus. Sand beach you can change to a walk to mineral springs, among which there are geothermal ones, which help to restore health.

Rosstourism has taken measures to develop cruise holidays in the Caspian. Considered not only domestic routes, but also international ones. Often, sea cruises dock with the Volga route. For such events, very good ships are needed, because there are often storms in the Caspian Sea.

Another area of ​​sea recreation in the Caspian Sea is health and healing. The local sea air helps to overcome many ailments. Many sanatoriums have been built on the seashore in Dagestan. People are getting healthier here mineral waters, mud, healing climate. Not without health and sports tourism. Leisure quite popular today. For those wishing to offer extreme, ski, ecological tourism. You can rest assured that the Caspian Sea and its coastal regions deserve to be visited.

The Caspian Sea is inland and is located in an extensive continental 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.

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 its vastness, only 62.6% of its area falls on waste 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 water 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 and other features of the Caspian Sea waters), as well as the Kura River , Zhaiyk (Ural), Terek, Sulak, Samur.

Physically and geographically and by nature, 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 ​​the maximum depths of which - Derbent - 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 Absheron threshold, which is a continuation. 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 up to 500 m high rise above the bottom of the basin.

The shores of the Caspian Sea are diverse. In the northern part of the sea, they are quite indented. Here are the Kizlyarsky, Agrakhansky, Mangyshlaksky bays and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea - 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, there is the Absheron Peninsula. To the east of it are the islands and banks of the Absheron archipelago, of which the most large island Residential. 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.

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 eastern 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 had been close to this mark for almost a century, this level position was considered as mean annual or secular. 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. The decrease in the level, with its small fluctuations (short-term insignificant rises in the level 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 average long-term of which reaches 40 cm, as well as surges. The latter are especially pronounced in the Northern Caspian. The northwestern coast is characterized by large surges created by the prevailing storms of the eastern and southeastern directions, especially during the cold period of the year. 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.

Climate... The Caspian Sea is located in the temperate and subtropical. Climatic conditions change in the meridional direction, since from north to south the sea stretches for almost 1200 km.

In the Caspian region, various circulation systems 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 most of the year for those passing by. The average annual 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 invasions 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 falling 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 distribution over the seasons is more even (10–18 mm per month). In general, we can talk about proximity to arid ones.

Water temperature... Distinctive features of the Caspian Sea (large differences in depths in different parts of the sea, character, 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. During 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; 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 to the surface of cold deep waters. 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 20 and 30 m in the middle part of the sea and 30 and 40 m in the south. 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 such factors as river runoff, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts The North Caspian Sea and between the North and Middle Caspian, the bottom topography, which determines the location of waters with different, mainly along isobaths, evaporation, providing a shortage of fresh water and the inflow of more saline ones. These factors collectively affect seasonal differences in salinity.

The North Caspian can be seen as a 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, the 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 Northern 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 largest difference between the maximum and minimum salinity was noted in the Apsheron sill area, 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 horizons of 40–70 m, the range of salinity fluctuations is no more than 1.1 ‰. Along the entire western coast to the Absheron Peninsula, there is a strip of desalinated 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 part, the 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 velocities of currents 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 directions of the wind, 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, and 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, and 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 seaside 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 the deep-water areas of the Caspian Sea, the main regularity remains in all seasons - a decrease in oxygen concentration with depth.
Due to the autumn-winter cooling, the density of the North Caspian waters increases to a value at which it becomes possible for the North Caspian waters with a high oxygen content to flow along the continental slope to significant depths of the Caspian Sea.

The seasonal distribution of oxygen is mainly associated with the annual course and the seasonal ratio of production and destruction processes taking place in the sea.

In spring, the production of oxygen in the process of photosynthesis very significantly overlaps the decrease in oxygen caused by a decrease in its solubility with an increase in water temperature in spring.

In the areas of estuarine seaside rivers feeding the Caspian Sea, in spring there is a sharp increase in the relative oxygen content, which in turn is an integral indicator of the intensification of the photosynthesis process and characterizes the degree of productivity of the zones of mixing of sea and river waters.

In summer, due to significant warming up 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.

Due to the high temperature of the waters, stratification of the water column, a large inflow of organic matter and its intense oxidation, oxygen is rapidly consumed with minimal input to the lower layers of the sea, as a result of which an oxygen deficiency zone forms in the North Caspian. Intensive photosynthesis in open waters of deep-water areas of the Middle and South Caspian covers the upper 25-meter layer, where oxygen saturation is more than 120%.

In autumn, in the well-aerated shallow-water regions of the Northern, Middle and Southern Caspian, the formation of oxygen fields is determined by the processes of water cooling and the less active, but still ongoing process of photosynthesis. The oxygen content is increasing.

The spatial distribution of nutrients in the Caspian Sea reveals the following regularities:

• high concentrations of nutrients are characteristic of the areas of the estuaries of rivers feeding the sea and shallow areas of the sea, subject to active anthropogenic influence (Baku Bay, Turkmenbashy Bay, waters adjacent to Makhachkala, Fort-Shevchenko, etc.);
• 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 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 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.

The dynamics of nutrient concentrations throughout the year in the Caspian Sea is influenced by such factors as seasonal fluctuations in the nutrient runoff in the sea, the seasonal ratio of production and destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter in the North Caspian Sea, winter processes. vertical circulation in deep sea areas.

In winter, a significant water area of ​​the North Caspian is covered with ice, but biochemical processes are actively developing in sub-ice water and in ice. The ice of the North Caspian, being a kind of accumulator of nutrients, transforms these substances entering the sea from 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 caused by intensive washing by river waters.

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 the summertime, redistribution of various forms of biogenic compounds is found in the waters of the Northern Caspian. 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 phytoplankton species, the content of phosphates and nitrates increases, while the concentration of silicon decreases, as there is an autumn outbreak of the development of diatoms.

For more than 150 years, oil has been produced on the shelf of the Caspian Sea.

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 ...

A total of 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.

The main sources of pollutants, including oil products, into the Caspian Sea are the outflow with river runoff, discharge of untreated industrial and agricultural wastewater, municipal waste water 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 ones are mainly confined to the region of the Absheron Peninsula, and increased oil pollution of the Southern Caspian is associated with oil production and oil exploration drilling, as well as with active volcanic activity (mud) in the zone 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 predicted 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.

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 in the Middle and South Caspian (from 200 to 700 m), since the lowest water temperatures are maintained here throughout the year (4.9– 5.9 ° C).

Mediterranean species... These are 2 types of mollusks, needle-fish, etc. At the beginning of the 20s of our century, the mithielastr mollusk penetrated here, later 2 types of shrimp (with mullet, when acclimatized), 2 types of mullet and flounder. Some species entered the Caspian after the opening of the Volga-Don Canal. Mediterranean species play an essential 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 original 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 - a complete ban on fishing for sturgeon in the sea and its regulation in rivers, an increase in the industrial breeding of sturgeon.