The Caspian Sea or the Caspian Sea is the largest closed, drainless body of water in the world. What are features of the Caspian Sea? It can be classified as the largest drainless lake, or like a sea (due to its size, as well as its bed formed by the earth's crust, the so-called oceanic type). The Caspian Sea stretches across Europe and Asia, in particular such countries as: Russia, Kazakhstan, Turkmenistan, Azerbaijan and Iran. In Russia, the Caspian coast is located on the territory of the Astrakhan region, as well as the Republic of Kalmykia and the Republic of Dagestan. This reservoir has a number of characteristics, with which this article will introduce you.

In the eastern direction, the Caspian Sea has a length of 435 kilometers, and in the northern direction, more than 1,000 kilometers. More than 40% of all lake water resources of our planet is concentrated here.

And scientists are still arguing about whether the Caspian is a lake or a sea. To date, it has been given the status of a lake, due to the fact that this inland reservoir has no natural connection with the world's oceans. At the same time, it can be considered a sea for several reasons: its vast territory, water reserves, as well as its salinity, ebbs and flows, storms, bottom topography (oceanic), indicates that the Caspian Sea originally belonged to an ancient reservoir , one with both the Black and the Sea of ​​Azov.

Approximately six thousand years ago, from the geological activity of the internal forces of the earth, the earth's crust sank, after which the Caspian Sea became a separate reservoir, which is located below the level of the world's oceans.

Feature of the Caspian Sea is also the fact that the indicators of the average salinity of the water here are weaker than in other seas of our planet. But after the Caspian was connected to the world ocean by a whole system of the Volga-Don canals, many countries (USA and others) demanded that its status of a lake be changed to the status of a sea, thereby opening it for navigation of all countries.

Having the status of a lake, the Caspian has no problems with its economic zones, and its territorial waters and shelves. The Russian Federation has a significant navy in the Caspian.

The Caspian Sea covers an area of ​​371,000 km². The coastline stretches for almost seven thousand kilometers, of which Russia owns 695 kilometers, in the northern and northwestern parts of the reservoir.

Treeless low-lying banks in the northern part of the reservoir are distinguished by a large number of channels of the Volga River. They form great amount different islands, as well as thickets and swampy areas. It is noteworthy that 80% of all water enters this lake from the Volga.

In the southern part of the Caspian Sea, on the territory of the Republic of Dagestan, stretched sandy beaches where seaside terraces meet in places. The waters of the lake here are replenished by such mountain rivers as: Gamriozen, Uluchay and Rubas.

The coastline of the Caspian Sea on the territory of Russia forms bays: Agrakhansky and Kizlyarsky.

The Caspian Sea is covered with ice only in one place, in the north, and even then it lasts only for two months a year. Throughout the Caspian coast, summer is characterized by low precipitation, high air and water temperatures. And this is another one feature of the Caspian Sea.

The increase in the depth of the lake begins from north to south. Max Depth reservoir - more than one kilometer, the average depth is about 200 meters (at the same time, the same indicator of the depth of water in the north does not exceed 4.5 meters, and the maximum is a mark of 27. 20% of the territory of the northern part of the Caspian Sea is very shallow, its depth does not exceed 1 meter.The deeper part of the Caspian, in which the Derbent depression is located, has a maximum depth of 788 m, and as for the southern regions of the lake, it is here that the greatest depths are recorded.

The level of salinity of the water gradually increases, as the Caspian Sea moves away from the Volga River delta, it varies from 1 to 12%.

In the Volga delta, 60 kilometers from the Caspian Sea, the ancient city of Astrakhan is located. On the Caspian coast, on the territory of Kalmykia, there is the city of Lagan. And on the Dagestan coast of the Caspian Sea there are such cities as: Kaspiysk, Makhachkala, Dagestan Lights, Izberbash and Derbent.

Flora and fauna

One of the mysteries of this lake is the presence on its territory of a population of seals, a smaller variety that lives in northern seas. Their fishing is prohibited in the territory Russian Federation. Their “living” on the Dagestan coast clearly indicates that the waters of the Caspian Sea in these places were restored in an ecological aspect after oil production was curtailed here.

The flora and fauna of the Caspian Sea is quite diverse. The most typical representatives underwater world of these places is: herring, gobies, sprat, mollusks (zebra mussel and cardium), various crustaceans. It is noteworthy that many species are endemic, i.e. those that are not found anywhere else.

The second group (about 25%) includes freshwater species that inhabited the Caspian Sea during different periods of lake desalination. They were perfectly able to adapt to low salinity. These fish include perch, carp, etc.

Belek Caspian seal

Interestingly, at the end of the ice age, some representatives of arctic invertebrates and fish (white fish, salmon), as well as such mammals as the seal, which breeds its offspring in the Northern Caspian, were able to penetrate here.

Mediterranean species belong to the fourth group of representatives of the Caspian marine fauna and flora. Most of them got here by accident (for example, with ballast water or attached to the bottoms of ships) after the 1950s. It was then when the Caspian and Azov Seas became connected by the network of the Volga-Don Canal. In addition, in the 30-40s of the last century, the Caspian was deliberately populated with mullet and two species of invertebrates (Abra and Nereis, which, thanks to successful acclimatization, became the main component of the sturgeon diet).

All of the above features of the Caspian Sea make this reservoir very interesting not only from a scientific point of view, but a great place for beach holiday, as well as fishing, due to the wide variety of fish species living here.

round goby

Fishing in the Caspian

The Caspian Sea, due to the species diversity of commercial fish (101 species live here), is very attractive for fishing enthusiasts. In recent years, fishing tourism has been actively developing here. And new articles will tell about fishing in the Caspian Sea, in the Astrakhan region, Kalmykia and Dagestan.

Caspian Beluga

The territory of Russia is washed by twelve seas belonging to the basins of three oceans. But one of these seas - the Caspian - is often called a lake, which sometimes confuses people who are poorly versed in geography.

Meanwhile, it is really more correct to call the Caspian a lake, not a sea. Why? Let's figure it out.

A bit of geography. Where is the Caspian Sea located?

Occupying an area that exceeds 370,000 square kilometers, the Caspian Sea stretches from north to south, dividing Europe and Asia with its water surface. Its coastline belongs to five different countries: Russia, Kazakhstan, Azerbaijan, Turkmenistan and Iran. Geographers conditionally divide its water area into three parts: Northern (25% of the area), Middle (36% of the area) and South Caspian (39% of the area), which differ in climate, geological setting and natural features. The coastline is mostly flat, indented by river channels, covered with vegetation, and in the northern part, where the Volga flows into the Caspian, it is also swampy.

The Caspian Sea has about 50 large and small islands, about a dozen bays and six large peninsulas. In addition to the Volga, about 130 rivers flow into it, and nine rivers form fairly wide and branched deltas. The annual drainage of the Volga is about 120 cubic kilometers. Together with other large rivers - the Terek, the Urals, the Emba and the Sulak - this accounts for up to 90% of the total annual runoff to the Caspian.

Why is the Caspian called a lake?

The main feature of any sea is the presence of straits connecting it with the ocean. The Caspian is a closed, or endorheic body of water, which receives river water, but does not connect with any ocean.


Its water contains a very small amount of salt compared to other seas (about 0.05%) and is considered slightly salty. Due to the lack of at least one strait connecting with the ocean, the Caspian is often called the largest lake in the world, since the lake is a completely closed reservoir, which is fed only by river water.

The waters of the Caspian Sea are not subject to international maritime laws, and its water area is divided among all countries that adjoin it, in proportion to the coastline.

Why is the Caspian called the sea?

Despite all of the above, most often in geography, as well as in international and domestic documents, the name “Caspian Sea” is used, and not “ Caspian lake". First of all, this is due to the size of the reservoir, which is much more typical for the sea than for the lake. Even, which is much smaller in area than the Caspian, locals often referred to as the sea. There are no other lakes in the world whose shores belong to five different countries at the same time.

In addition, attention should be paid to the structure of the bottom, which near the Caspian Sea has a pronounced oceanic type. Once the Caspian Sea, most likely, was connected with the Mediterranean, but tectonic processes and drying up separated it from the World Ocean. More than fifty islands are located in the Caspian Sea, and the area of ​​some of them is quite large, even by international standards they are considered large. All this makes it possible to call the Caspian a sea, not a lake.

origin of name

Why is this sea (or lake) called Caspian? The origin of any name is often associated with ancient history terrain. Different peoples who lived on the shores of the Caspian called it differently. More than seventy names of this reservoir have been preserved in history - it was called the Hyrcanian, Derbent, Sarai Sea, etc.


Iranians and Azerbaijanis still call it the Khazar Sea. It began to be called Caspian by the name of the ancient tribe of nomadic horse breeders who lived in the steppes adjacent to its coast - a large tribe of Caspians. It was they who gave the name to the largest lake on our planet - the Caspian Sea.

The Caspian Sea is the largest drainless lake on Earth, located at the junction of Europe and Asia, called the sea due to the fact that its bed is composed of oceanic-type earth's crust. The Caspian Sea is a drainless lake, and the water in it 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 it was 27.16 m below sea level. 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, from west to east - from 195 to 435 kilometers, on average 310-320 kilometers. The Caspian Sea is conditionally divided according to physical and geographical conditions into 3 parts - the Northern Caspian, the Middle Caspian and the Southern Caspian. The conditional border between the North and Middle Caspian runs along the line of about. Chechnya - Cape Tyub-Karagansky, between the Middle and South Caspian - along the line of about. Residential - Cape Gan-Gulu. The area of ​​the Northern, Middle and Southern Caspian 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-lying and smooth. In the northern part, the coastline is indented 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. On the east coast limestone coasts adjoining semi-deserts and deserts predominate. The most winding coasts are on the western coast near the Apsheron Peninsula and on the eastern coast near the Kazakh Gulf and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian Sea.

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 Northern Caspian is 4-8 meters, the maximum does not exceed 25 meters. The Mangyshlak threshold separates the Northern Caspian from the Middle. The Middle Caspian is quite deep, the depth of water in the Derbent depression reaches 788 meters. The Apsheron threshold separates the Middle and South Caspian. The South Caspian is considered deep water, the depth of water in the South Caspian depression reaches 1025 meters from the surface of the Caspian Sea. Shell sands are widespread on the Caspian shelf, deep-water areas are covered with silty sediments, and in some areas there is an outcrop of bedrock. Temperature regime 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 water temperature difference is about 10 °C . For shallow water areas with depths less than 25 m, the annual amplitude can reach 25-26 °C. The average water temperature at west coast 1-2 °C higher than that of the eastern one, and in the open sea the water temperature is 2-4 °C higher than that of the coasts.

Animal and plant world The fauna of the Caspian is represented by 1809 species, of which 415 are vertebrates. 101 species of fish are registered in the Caspian Sea, and most of the world's stocks of sturgeon are concentrated in it, as well as such freshwater fish as vobla, carp, pike perch. The Caspian Sea is the habitat of such fish as carp, mullet, sprat, kutum, bream, salmon, perch, pike. The Caspian Sea is also inhabited by a marine mammal - the Caspian seal. The flora of the Caspian Sea and its coast is represented by 728 species. Of the plants in the Caspian Sea, algae predominate - blue-green, diatoms, red, brown, char and others, of flowering - zoster and ruppia. By origin, the flora belongs mainly to the Neogene age, however, some plants were brought into the Caspian Sea by man consciously or on the bottoms of ships.

Minerals Many oil and gas fields are being developed in the Caspian Sea. The proven oil resources in the Caspian Sea are about 10 billion tons, the total resources of oil and gas condensate are estimated at 18-20 billion tons. Oil production in the Caspian Sea began in 1820, when the first oil well was drilled on the Absheron shelf. In the second half of the 19th century, oil production began on an industrial scale on the Absheron Peninsula, and then on other territories. In addition to oil and gas production, salt, limestone, stone, sand, and clay are also mined on the coast of the Caspian Sea and the Caspian shelf.

The Caspian Sea is located in different geographical zones. It plays a big role in world history, is an important economic region and a source of resources. The Caspian Sea is a unique body of water.

Short description

This sea is large. The bottom is covered with oceanic bark. These factors make it possible to classify it as a sea.

It is a closed reservoir, has no drains and is not connected with the waters of the oceans. Therefore, it can also be attributed to the category of lakes. In this case, it will be the largest lake on the planet.

The approximate area of ​​the Caspian Sea is about 370 thousand square kilometers. The volume of the sea changes depending on the various fluctuations in the water level. The average value is 80 thousand cubic kilometers. The depth varies in its parts: the southern one has a greater depth than the northern one. The average depth is 208 meters, the highest value in the southern part exceeds 1000 meters.

The Caspian Sea plays an important role in the development of trade relations between the countries. The resources mined in it, as well as other trade items, were transported to different countries since the development of navigation at sea. Since the Middle Ages, merchants have delivered exotic goods, spices and furs. Today, in addition to the transportation of resources, by sea, ferry crossings between cities. The Caspian Sea is also connected by a navigable canal through the rivers with the Sea of ​​Azov.

Geographic characteristics

The Caspian Sea is located between two continents - Europe and Asia. Washes the territory of several countries. These are Russia, Kazakhstan, Iran, Turkmenistan and Azerbaijan.

It has more than 50 islands, both large and small in size. For example, the islands of Ashur-Ada, Tyuleniy, Chigil, Gum, Zenbil. As well as the peninsulas, the most significant - Absheron, Mangyshlak, Agrakhan and others.

The Caspian Sea receives the main influx of water resources from the rivers flowing into it. In total, there are 130 tributaries of this reservoir. The largest is the Volga River, which brings the bulk of the water. The Kheras, Ural, Terek, Astarchay, Kura, Sulak and many others rivers also flow into it.

The waters of this sea form many bays. Among the largest are: Agrakhansky, Kizlyarsky, Turkmenbashi, Girkan Bay. In the eastern part there is a bay-lake called Kara-Bogaz-Gol. It communicates with the sea by a small strait.

Climate

The climate is characterized geographical location sea, therefore, it has several types: from continental in the northern region to subtropical in the south. This affects the air and water temperatures, which have great contrasts depending on the part of the sea, especially in the cold season.

in winter average temperature air in the northern region is about -10 degrees, water reaches a value of -1 degree.

In the southern region, the temperature of air and water in winter warms up to an average of +10 degrees.

In summer, the air temperature in the northern zone reaches +25 degrees. Much hotter in the south. The maximum recorded value here is + 44 degrees.

Resources

The natural resources of the Caspian Sea contain large reserves of various deposits.

One of the most valuable resources of the Caspian Sea is oil. Mining has been carried out since about 1820. Springs were opened on the territory of the seabed and its coast. By the beginning of the new century, the Caspian was at the forefront in obtaining this valuable product. During this time, thousands of wells were opened, which made it possible to extract oil on a huge industrial scale.

The Caspian Sea and the territory adjacent to it also have rich deposits of natural gas, mineral salts, sand, lime, several types of natural clay and rocks.

Inhabitants and fisheries

The biological resources of the Caspian Sea are very diverse and highly productive. It contains more than 1500 species of inhabitants, rich in commercial fish species. The population depends on climatic conditions in different parts of the sea.

In the northern part of the sea, pike perch, bream, catfish, asp, pike and other species are more common. Gobies, mullet, bream, herring live in the western and eastern. Southern waters are rich in various representatives. One of the many are sturgeons. According to their content, this sea occupies a leading place among other reservoirs.

Among the wide variety, tuna, beluga, stellate sturgeon, sprat and many others are also caught. In addition, there are mollusks, crayfish, echinoderms and jellyfish.

The mammal Caspian seal lives in the Caspian Sea, or This animal is unique and lives only in these waters.

The sea is also characterized by a high content of various algae, for example, blue-green, red, brown; sea ​​grass and phytoplankton.

Ecology

The extraction and transportation of oil has a huge negative impact on the ecological situation of the sea. The ingress of oil products into water is almost inevitable. Oil stains cause irreparable damage to marine habitats.

The main inflow of water resources to the Caspian Sea is provided by rivers. Unfortunately, most of them have a high level of pollution, which degrades the quality of the water in the sea.

Industrial and domestic effluents from the surrounding cities are poured into the sea in large quantities, which also damages the environment.

Poaching causes great damage to the marine habitat. Sturgeon species are the main target for illegal catching. This significantly reduces the number of sturgeon and threatens the entire population of this type.

The above information will help to assess the resources of the Caspian Sea, to briefly study the characteristics and ecological situation of this unique reservoir.

The Caspian Sea is a residual (relic) reservoir of the much larger Khvalyn Sea, which once occupied the entire Caspian lowland. In the epoch of the Khvalynsk transgression, when the level of the Caspian Sea was much higher than the modern one, it connected with the Black Sea through the strait, which passed on the site of the Kumo-Manych lowland. The modern Caspian Sea is the largest lake in the world, only for its size it is ranked among the seas. The area of ​​its water surface is 424,000 km2. The sea level dropped after the ice age and now lies 28 m below the sea level.

Geographic location of the Caspian Sea. Extended map

The huge basin of the Caspian Sea is morphologically divided 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) middle- with an average depth of 200 m and a maximum depth of 790 m and
3) southern- the deepest, with the greatest depth up to 980 m and with an average depth of 325 m.
Deep depressions in the middle and southern parts of the sea are separated by an underwater sill running from the Apsheron Peninsula to Krasnovodsk.

Water balance of the Caspian Sea

The bays of the Caspian Sea - Kaydak, 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 Kara-Bogaz-Gol Bay, in essence, is a huge shallow (up to 10 m deep) independent lake, with an area equal to Lake Ladoga. The salinity of the waters of the Caspian Sea is relatively low, on average about 12.6°/oo, which is about 3 times less than the salinity of the waters of the world ocean.

flows into the Caspian Sea big number tributaries: 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 approximately 325 km 3. All this huge mass of water entering the sea evaporates from its surface into the atmosphere. The Caspian Sea is considered drainless, 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 lower than the level of the Caspian Sea. Kara-Bogaz-Gol is separated from the sea by a narrow sandy spit, leaving a strait up to 200 m wide in places. Through this strait, water flows from the Caspian Sea to the bay (an average of more than 20 / km 3 per year), which, therefore, plays the role of a giant evaporator. The water in the Kara-Bogaz-Gol Bay reaches exceptionally high salinity (169°/oo).

Kara-Bogaz-Gol is of great importance for the chemical industry. This 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 watermaker. If there were no runoff from the sea to Kara-Bogaz-Gol, its salinity would increase. In table. 1 shows the water balance of the Caspian Sea according to B. D. Zaikov.

Table 1. Water balance of the Caspian Sea

The arrival of water	Layer		Water consumption	Layer
	in mm	in km 3		in mm	in km 3
Precipitation on the water surface	177	71,1	Evaporation from the water surface	978	392,3
surface inflow	808	324,2	Drain to Kara-Bogaz-Gol Bay	21	22,2
Underground inflow	14	5,5
Total	999	400,8	Total	999	400,8

The rivers carry 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.

In the Caspian Sea, there are more or less constant currents with a general counterclockwise direction. In summer, the waters of the Caspian Sea are very warm, and the water temperature near the surface reaches 25-27 ° (see Fig. 84). In winter, the sea slowly cools down and for the most part maintains a positive temperature (1 °). Only its shallow northern part freezes over, where floating ice and the 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 that do not have tidal currents. Fluctuations in water level are relatively small. If we take into account historical data, then the long-term amplitude of the level fluctuation 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 under water near Baku, as well as a number of other historical data.

Lowering of 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 from 1930. In 15 years (from 1930 to 1945), the sea level fell by almost 2 m, As a result, the area of ​​\u200b\u200bits water surface decreased almost 20,000 km2. The shallow bays of Kaydak and Komsomolets have dried up and turned into sores, and in some places the modern sea has receded by 10 km or more. The lowering of the level caused great difficulties in the work of the ports of the Caspian coast and sharply worsened the conditions of navigation, especially in the Northern Caspian. In this regard, the problem of the level of the Caspian Sea in the 20th century attracted much attention.

There are two points of view on the issue of 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 ongoing slow sinking of the coast and the entire basin. In favor of this view are known facts lowering of the seashores in the region of Baku and in other places. Proponents of another, hydrometeorological point of view (B. A. Apollon, B. D. Zaikov, and others) see the main reason for the decrease in sea level as a change in the ratio of elements of the water balance. As B. D. Zaikov showed, the drop in the level of the Caspian Sea is connected and explained by the exceptionally low water content of the Volga in 1930-1945; its flow was significantly below the norm. As for the influence of epeirogenic fluctuations on the level of the Caspian Sea, their role is apparently very insignificant, since the magnitude of the ongoing lowering of the coast and the bottom of the sea is calculated in millimeters.