Caspian lake. Why is the Caspian lake called the sea? Why the Caspian Sea cannot be called either a sea or a lake

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, have been 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 transporting resources, ferries between cities are carried out by sea. 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 by the geographical location of the 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, the average air temperature in the northern region is about -10 degrees, the water reaches -1 degrees.

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. 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.

Where Europe converges with Asia, there is one of the unique reservoirs, which is officially called the sea, and unofficially - the lake - the Caspian Sea, washing the shores of several countries at once with its waters. , or rather, its northeastern part, goes just to the Caspian coast. What mysteries does the Caspian hold, how big a role does it play in the life of the country, and what benefits can people bring to the sea itself?

Geography of the Caspian Sea

Researchers are still arguing what the Caspian Sea is - a lake or a sea. The fact is that this reservoir is the largest of all drainless. These are called those that have no connection with the oceans.

All the rivers of the Caspian Sea originate on land, but do not reach the ocean shores. Thus, it is closed and may well be called a lake. However, the Caspian is quite large, moreover, its bottom is the earth's crust, which belongs to the oceanic type. This indicates that the sea appeared here millions of years ago.

The fact that once on the planet, or rather, on the territory where Europe and Asia are located today, the huge prehistoric Sarmatian Sea splashed - this is the name given to it by scientists. This was 12 million years ago. Water covered the entire space of the current land.

The Caucasus and the Crimea were islands in this incredibly large sea. However, it gradually desalinated and dried up due to the slow rise of the land. As a result, on the site of the Sarmatian Sea, peculiar "puddles" were formed - the Caspian, Black, Aral, Azov Seas.

Finding the Caspian Sea today on a geographical map is quite simple. It is located in the region of Asia Minor and is separated from the Black Sea by the Caucasus, which acts as a kind of isthmus between these two reservoirs. It has an elongated shape from north to south. Its coordinates are 36°34"–47°13" north latitude and 46°–56° east longitude. Modern borders are the coasts of five states:

Russia.
Azerbaijan.
Turkmenistan.
Kazakhstan.
Iran.

Geographers divide the territory of the sea into the North, Middle and South Caspian, and the southern part of it occupies about 40% of the area, and the northern part is only 25%. There are also limits to these divisions. So, the Middle Caspian is separated from the North by a conditional line drawn from Cape Tyub-Karagan to the island of Chechen. And the border between the South and the Middle passes through Cape Gan-Gul and Chilov Island.

Area and depth

Many are interested in what is the area of the Caspian Sea, but these parameters change periodically. It all depends on seasonal fluctuations in depth. So, if the water level in the sea is about 27 meters, the reservoir can reach over 370 thousand square kilometers. During these periods, it becomes full-flowing, and holds almost 45% of the total volume of fresh lake water on the planet.

The Caspian Sea is heterogeneous in terms of depth parameters. So, the shallowest part is the northern one, its average depth does not exceed 4 meters, and the maximum is 25 meters. The southern part is the deepest, in the region of the South Caspian depression it is 1025 meters. In general, the researchers found that the average depth of the reservoir is 208 meters according to the bathygraphic curve.

The Caspian lake is in third place in terms of depth after the lakes of Baikal and Tanganyika. As for sea level, it fluctuates significantly. Scientific measurements of the reservoir began in 1837. Scientists, based on historical documents and archaeological research, argue that the highest water level was observed at the turn of the 13th-14th centuries, then the decline began.

For three thousand years of our civilization, the water level in the Caspian has changed by 15 meters. The reasons may be very different. First of all, these are geological changes in the state of the earth's crust, as well as climate fluctuations in a given region and human actions.

Temperature and climate

Since today not only industrial enterprises, but also resorts are located in the Caspian basin, the temperature of the Caspian Sea is of great interest to many. This indicator is also subject to seasonal changes, and they are very significant.

In winter, the difference in temperature fluctuations is observed within 10 degrees. In the southern part of the reservoir, water in the winter season has an average temperature of 11 degrees, while in the northern part of the sea this temperature is no more than 0.5 degrees, and sometimes even a slight glaciation is observed. The northern regions, as the most shallow, warm up faster in summer and can reach up to 26 degrees. At the same time, the water temperature in the western part of the reservoir is permanently higher than in the eastern part.

The summer period, which lasts from June to September, makes the temperature indicators the most uniform throughout the sea. At this time, in the upper layers, the water warms up to 26 degrees, and in the southern part it can increase up to 28 degrees. By the velvet season in shallow areas, the water is able to warm up even more and reaches 32 degrees.

In addition, in summer there is such a phenomenon as the rise of deep water layers to the surface. This is the so-called upwelling, however, scientists observe it not throughout the entire water area, but mainly only in the east, sometimes deep waters also rise in the southern part of the reservoir. As a result, the average water temperature can be understood by 10 degrees.

As in other marine water bodies, the water in the Caspian Sea is salty. However, the level of salt saturation may vary depending on its individual areas. The salt concentration is highest in the western and southern parts of the reservoir. In the northern regions, sea water is constantly diluted with fresh water from rivers. However, throughout the sea, the salt concentration varies depending on the season of the year.

In addition, the reason that the water becomes saltier or fresher is the winds. For example, in the South and Middle Caspian, these fluctuations are weakly expressed, in contrast to the North.

The climate of this maritime region also varies. The southern part of the sea is in a subtropical climate, the middle part is temperate, and the northern part is continental. As a result, the air temperature on the coast is different.

It is worth noting that it is hottest in the south and southeast of the reservoir. Here, the temperature can sometimes reach up to 44 degrees in summer, and the average temperature is 26-27 degrees. The north of the reservoir in the summer also cannot complain about the cold - up to 25 degrees of air temperature is recorded here. As for winter, the air temperature in the north can reach -10 degrees, and in the south - up to +10 degrees.

Pool Features

There is no need to assume that the Caspian is just a closed body of water, bounded by shores. On the map, the sea has fairly even shores, but in fact its borders are indented by small capes and peninsulas, as well as channels and estuaries. The coastline is about 7 thousand kilometers (including the islands).

The coast of the lake in its northern part looks low, there is some waterlogging due to the presence of many channels. From the east, the Caspian coast is mainly limestone, and the territories smoothly turn into semi-desert lands. The sinuosity of the coastal edges is highest in the east and west.

Any large body of water cannot do without islands, and the Caspian is no exception. The islands of the Caspian Sea are diverse, their total number is almost 50 islands of various sizes. The largest ones include:

Boyuk-Zira;
Seals;
Chechen;
Ashur-Ada;
Ogurchinsky;
Kur-Dashi;

The coast of the Caspian Sea is also rich in peninsulas, among which are Mangyshlak, Apsheron, Tyub-Karagan. Finally, the geography of the Caspian includes many large and small bays. The most famous of them are:

Kizlyarsky;
Kara-Bogaz-Gol;
Mangyshlak;
Gyzylagach;
Turkmenbashi;
Astrakhan (Astrakhan);
Hyrcanus.

Of these bays, one can especially distinguish Kara-Bogaz-Gol, which is located in the eastern part of the sea and today belongs to Turkmenistan. Until the end of the twentieth century, it was a kind of Caspian lagoon, which was connected to the "big water" by the strait. In the 1980s, back in the days of the USSR, a dam was first built here, and then a dam, as a result of which the water level in the bay was lowered.

To date, the situation has returned to the starting point, since the strait was able to restore. Water enters the bay in the amount of 10-17 cubic kilometers annually. However, due to the hot climate, it evaporates, so the Kara-Bogaz-Gol Bay is extremely salty.

The Caspian Sea, like other similar water bodies, has a rich flora and fauna. A variety of algae predominate here, and researchers believe that most of the Caspian is of local origin. However, it is also possible that some algae were brought here artificially - for example, on the bottoms of merchant ships from other seas.

The Caspian is quite diverse. There are over 100 types of fish. It is here that the famous sturgeon and other fish of the same family are found. Basically, the fish of the Caspian are those that live in fresh or low-salt waters: pike, carp, salmon, mullet, perch, carp, some of which are listed in. You can meet seals in the sea.

Development of waters and seabed

Who among us does not remember the famous phrase from geography textbooks: "The Volga flows into the Caspian Sea." This river is the largest of those whose mouth is the Caspian. Every year it delivers up to 224 cubic kilometers of fresh water to the sea. But there are other, smaller ones that also rush to here. In addition to the Volga, these are:

Terek.
Ural.
Samur.
Sulak.

These rivers flow through the territory of Russia, and in addition to them, the waters of the rivers Atrek (Turkmenistan), Kura (), Sefidrud (Iran), Emba (Kazakhstan) flow into the Caspian. In total, out of 130 various rivers flowing into the Caspian Sea, the mouths of nine water streams are formed in the form of a delta.

The development of the lake took place over many centuries. Today, the ports of the Caspian Sea connect the shores of the reservoir with trade routes. Of the Russian ports, the most important are Makhachkala and Astrakhan, from which ships are constantly sent to Kazakh Aktau, Azerbaijani Baku and other coastal shores of the Caspian Sea. In addition, it is connected with the Sea of Azov, where they get through the Don and Volga rivers, as well as through the Volga-Don Canal.

Oil production is an important direction in the economic development of the Caspian basin and the sea area itself. The oil resources of the sea currently amount to approximately 10 billion tons - these are the estimates given by the researchers. If we add gas condensate to this, then the reserves will double.

Oil production is the most important sector of the economy of the countries of the Caspian region, therefore, for many years, disagreements regarding the use of the resources of the sea have not been resolved. During the existence of the USSR, the territory of the Caspian Sea belonged to the Soviet Union and Iran.

Until now, there are legal documents on the division of the reservoir and the use of its shelf, which were concluded between Iran and the USSR. At the same time, disputes regarding the legal division of territories do not stop. So, Iran proposes to divide equally between the five countries, and three former Soviet republics insist that the reservoir be divided along the median line of demarcation.

This issue remains very serious, because depending on where the sea should be divided, not only the volume of oil production for each Caspian state depends, but also the use of other resources of the reservoir. Here we can talk, first of all, about fisheries, because the sea is very generous with fish stocks.

They get not only fish, but also the famous caviar, as well as a seal. However, the reproduction of fish stock today would be much more efficient if it were not for the poachers of the Caspian Sea, who organize illegal sturgeon catching and illegally harvest caviar.

At the same time, they exist in almost all the Caspian countries, so that the fight against them is common for the neighboring countries of the Caspian basin. As a result, sturgeon exports have been limited in recent years, as both Russia and other Caspian countries are interested in preserving this natural wealth of the region.

Poaching is a serious problem, and today Russia, together with Azerbaijan, Iran, Kazakhstan and Turkmenistan, are developing measures aimed at legally limiting illegal fishing.

However, there is another big problem of the Caspian Sea - the pollution of sea waters. The reason is oil production, as well as the transportation of oil by sea. Do not forget that large cities located on the banks of the reservoir are a constant source of water pollution. In addition, industrial enterprises, despite strict bans, sometimes still dump waste into rivers, which then end up in the sea.

Environmental violations lead not only to general pollution of the Caspian waters, but also to a change in the boundaries of the reservoir itself (waterlogging, drying up, and so on). But what is the significance of the Caspian Sea for the entire region, it is not even worth talking about.

Rest in the resorts of the Caspian Sea

In order to understand what human civilization can lose by losing the Caspian Sea, you can look at its photo. This body of water is an amazing place for a good rest, and seascapes invariably impress everyone who comes here. Rest spent on the Caspian Sea is no worse than on the Black Sea shores. Fresh air, mild climate and comfortable beaches - that's what it can give tourists.

If you decide to go to the Caspian Sea, the prices for holidays will pleasantly surprise you. Tourism is valued in many ways precisely because it turns out to be inexpensive compared to what awaits tourists traveling to resorts in other regions of the planet. Residents of Russia can relax quite cheaply within their own country and at the same time receive excellent service that does not differ in level from the Mediterranean.

There are several resorts in Russian cities (most of which are in), which are especially popular with tourists. This:

Astrakhan;
Dagestan Lights;
Kaspiysk;
Izberbash;
Lagan.

If tourists go to Derbent, first of all, to see its ancient sights, and to Astrakhan - to enjoy fishing, then the places for recreation in Makhachkala are among the most comfortable and comfortable beaches of the Caspian Sea.

This resort attracts not only with comfortable rest, but also with the opportunity to improve health, because there are thermal and mineral springs here. Of the foreign resorts, Kazakh Aktau, Azerbaijani Sumgayit and the Turkmen Avaza recreation area can be noted.

Today the Caspian is one of the most important world regions in economic terms. Without it, it is impossible to imagine modern Eurasia and, moreover, the history of Russia. This means that the state of this reservoir should be protected by the state.

The Caspian Sea is one of the largest salt water bodies of the Earth, located at the junction of Europe and Asia. Its total area is about 370 thousand square meters. km. The reservoir receives more than 100 water flows. The largest rivers flowing into - Volga, Ural, Emba, Terek, Sulak, Samur, Kura, Atrek, Sefidrud.

The Volga River - the pearl of Russia

The Volga is a river flowing on the territory of the Russian Federation, partially crossing Kazakhstan. It belongs to the category of the largest and longest rivers on Earth. The total length of the Volga is more than 3500 km. The river originates in the village of Volgoverkhovye, Tver region, located on the territory of the Russian Federation. After that, it continues its movement through the territory of the Russian Federation.

It flows into the Caspian Sea, but does not have a direct outlet to the World Ocean, so it is classified as an internal drain. The watercourse receives about 200 tributaries and has more than 150 thousand drains. Today, reservoirs have been built on the river, allowing to regulate the flow, due to which the fluctuations in the water level have been sharply reduced.

The fishery of the river is diverse. Melon growing prevails in the Volga region: the fields are occupied by grain and industrial crops; salt is mined. Oil and gas fields have been discovered in the Ural region. The Volga is the largest river flowing into the Caspian Sea, so it is of great importance for Russia. The main transport facility that allows crossing this stream is the longest one in Russia.

Ural - a river in Eastern Europe

The Ural, like the Volga River, flows on the territory of two states - Kazakhstan and the Russian Federation. Historical name - Yaik. It originates in Bashkortostan at the top of the Uraltau ridge. The Ural River flows into the Caspian Sea. Its basin is the sixth largest in the Russian Federation, and the area is more than 230 square meters. km. An interesting fact: the Ural River, contrary to popular belief, belongs to the inland European river, and only its upper course in Russia belongs to Asia.

The mouth of the stream gradually becomes shallower. At this point, the river splits into several branches. This feature is typical throughout the entire length of the channel. During floods, you can watch the Ural overflow its banks, in principle, like many other Russian rivers flowing into the Caspian Sea. This is especially observed in places with a gently sloping coastline. Flooding occurs at a distance of up to 7 meters from the riverbed.

Emba - the river of Kazakhstan

Emba is a river flowing on the territory of the Republic of Kazakhstan. The name comes from the Turkmen language, literally translated as "the valley of food." The river basin with an area of 40 thousand square meters. km. The river begins its journey in the mountains of Mugodzhary and, flowing along, is lost among the swamps. Asking which rivers flow into the Caspian Sea, we can say that in full-flowing years, the Emba reaches its basin.

Natural resources such as oil and gas are being exploited along the coastline of the river. The issue of passing the border between Europe and Asia along the Emba watercourse, as in the case of the river. Ural, an open topic today. The reason for this is a natural factor: the mountains of the Ural Range, which are the main reference point for drawing borders, disappear, forming a homogeneous area.

Terek - mountain water stream

Terek is a river of the North Caucasus. The name literally translates from Turkic as "poplar". The Terek flows out of the glacier of Mount Zilga-Khokh, located in the Trusovsky Gorge of the Caucasus Range. passes through the lands of many states: North Ossetia, Georgia, Stavropol Territory, Kabardino-Balkaria, Dagestan and the Chechen Republic. It flows into the Caspian Sea and the Arkhangelsk Bay. The length of the river is just over 600 km, the basin area is about 43 thousand square meters. km. An interesting fact is that every 60-70 years the flow forms a new transit arm, while the old one loses its strength and disappears.

The Terek, like other rivers flowing into the Caspian Sea, is widely used to satisfy human economic needs: it is used to irrigate the arid territories of the adjacent lowlands. There are also several hydroelectric power plants on the water stream, the total average annual output of which is more than 200 million kWh. In the near future, it is planned to launch additional additional stations.

Sulak - water stream of Dagestan

Sulak is a river that connects the streams of the Avar Koisu and the Andi Koisu. It flows through the territory of Dagestan. It starts in the Main Sulak Canyon and ends its journey in the waters of the Caspian Sea. The main purpose of the river is the water supply of two cities of Dagestan - Makhachkala and Kaspiysk. Also, several hydroelectric power stations are already located on the river, it is planned to launch new ones to increase the generated capacity.

Samur - the pearl of South Dagestan

Samur is the second largest river in Dagestan. Literally, the name from the Indo-Aryan is translated as "an abundance of water." It originates at the foot of Mount Guton; It flows into the waters of the Caspian Sea in two branches - Samur and Small Samur. The total length of the river is just over 200 km.

All rivers flowing into the Caspian Sea are of great importance for the territories through which they flow. Samur is no exception. The main direction of using the river is irrigation of lands and providing residents of nearby cities with drinking water. It was because of this that a hydroelectric complex and a number of the Samur-Divichinsky canal were built.

At the beginning of the 20th century (2010), Russia and Azerbaijan signed an interstate agreement requiring both sides to rationally use the resources of the Samur River. The same agreement introduced territorial changes between these countries. The border between the two states has been moved to the middle of the hydroelectric complex.

Kura - the largest river of Transcaucasia

Asking the question which rivers flow into the Caspian Sea, I want to describe the flow of the Kuru. It flows on the land of three states at once: Turkey, Georgia, Azerbaijan. The length of the stream is more than 1000 km, the total area of the basin is about 200 thousand square meters. km. Part of the basin is located on the territory of Armenia and Iran. The source of the river is located in the Turkish province of Kars, flows into the waters of the Caspian Sea. The path of the river is thorny, laid among hollows and gorges, for which it got its name, which in Megrelian means “nibble”, that is, the Kura is a river that “gnaws” itself even among the mountains.

There are many cities on it, such as Borjomi, Tbilisi, Mtskheta and others. It plays an important role in meeting the economic needs of the inhabitants of these cities: fishing is carried out, hydroelectric power stations are located, and the Mingachevir reservoir created on the river is one of the main fresh water reserves for Azerbaijan. Unfortunately, the ecological state of the stream leaves much to be desired: the level of harmful substances exceeds the permissible limits by several times.

Features of the Atrek River

Atrek is a river located on the territory of Iran and Turkmenistan. It originates in the Turkmen-Kharasan mountains. Due to the active use in economic needs for irrigation of land, the river became shallow. For this reason, it reaches the Caspian Sea only during the flood period.

Sefidrud - the abundant river of the Caspian

Sefidrud is a major river of the Iranian state. It was originally formed by the confluence of two water streams - Kyzyluzen and Shakhrud. Now it flows out of the Shabanau reservoir and flows into the depths of the Caspian Sea. The total length of the river is over 700 km. The creation of a reservoir has become a necessity. It made it possible to minimize the risks of flooding, thereby securing the cities located in the river delta. The waters are used for irrigation of land with a total area of more than 200 thousand hectares of land.

As can be seen from the presented material, the Earth's water resources are in an unsatisfactory state. The rivers flowing into the Caspian Sea are actively used by man to meet his needs. And this has a detrimental effect on their condition: watercourses are depleted and polluted. That is why scientists around the world are sounding the alarm and conducting active propaganda, calling for saving and conserving water on Earth.

The Caspian Sea is the largest lake on our planet, which is located in a depression on the earth's surface (the so-called Aral-Caspian lowland) on the territory of Russia, Turkmenistan, Kazakhstan, Azerbaijan and Iran. Although they consider it as a lake, because it is not connected with the World Ocean, but by the nature of the formation processes and the history of origin, in terms of its size, the Caspian Sea is a sea.

The area of the Caspian Sea is about 371 thousand km2. The sea, stretched from north to south, has a length of about 1200 km and an average width of 320 km. The length of the coastline is about 7 thousand km. The Caspian Sea is located 28.5 m below the level of the World Ocean and its greatest depth is 1025 m. There are about 50 islands in the Caspian Sea, mostly small in area. Large islands include such islands as Tyuleniy, Kulaly, Zhiloy, Chechen, Artem, Ogurchinsky. There are also many bays in the sea, for example: Kizlyarsky, Komsomolets, Kazakh, Agrakhansky, etc.

The Caspian Sea is fed by more than 130 rivers. The largest amount of water (about 88% of the total flow) is brought by the Ural, Volga, Terek, Emba rivers, which flow into the northern part of the sea. About 7% of the runoff is provided by the large rivers Kura, Samur, Sulak and small rivers flowing into the sea on the western coast. The Heraz, Gorgan, Sefidrud rivers flow into the southern Iranian coast, which bring only 5% of the flow. Not a single river flows into the eastern part of the sea. The water in the Caspian Sea is salty, its salinity ranges from 0.3‰ to 13‰.

The shores of the Caspian Sea

The shores have a different landscape. The shores of the northern part of the sea are low and gentle, surrounded by low semi-desert and somewhat elevated desert. In the south, the shores are partially low-lying, they are bordered by a coastal lowland of a small area, behind which the Elburs ridge runs along the coast, which in some places comes close to the coast. In the west, the ridges of the Greater Caucasus approach the coast. In the east there is an abrasion coast, worked out in limestones, semi-desert and desert plateaus approach it. The coastline is very variable due to periodic fluctuations in water levels.

The climate of the Caspian Sea is different:

Continental in the north;

Moderate in the middle

Subtropical in the south.

At the same time, severe frosts and snowstorms are raging on the northern coast, and fruit trees and magnolias bloom on the southern coast. In winter, strong storm winds rage on the sea.

Large cities and ports are located on the coast of the Caspian Sea: Baku, Lankaran, Turkmenbashi, Lagan, Makhachkala, Kaspiysk, Izberbash, Astrakhan, etc.

The fauna of the Caspian Sea is represented by 1809 animal species. More than 70 species of fish are found in the sea, including: herring, gobies, stellate sturgeon, sturgeon, beluga, white salmon, sterlet, pike perch, carp, bream, vobla, etc. Of the marine mammals in the lake, only the world's smallest Caspian seal is found, which not found in other seas. The Caspian lies on the main bird migration route between Asia, Europe and the Middle East. Every year, about 12 million birds fly over the Caspian during their migration period, and another 5 million usually winter here.

Vegetable world

The flora of the Caspian Sea and its coast is 728 species. Basically, algae inhabit the sea: diatoms, blue-green, red, char, brown and others, from flowering ones - rupee and zoster.

The Caspian Sea is rich in natural resources, many oil and gas fields are being developed in it, in addition, limestone, salt, sand, stone and clay are also mined here. The Caspian Sea is connected by the Volga-Don Canal with the Sea of Azov, shipping is well developed. A lot of different fish are caught in the reservoir, including more than 90% of the world's sturgeon catch.

The Caspian Sea is also a recreation area, on its shores there are rest houses, tourist bases and sanatoriums.

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According to one hypothesis, the Caspian Sea (among the ancient Slavs - the Khvalyn Sea) got its name in honor of the Caspian tribes who lived before our era on its southwestern coast.

The Caspian Sea washes the shores of five states: Russia, Azerbaijan, Iran, Turkmenistan and Kazakhstan.

The Caspian Sea is elongated in the meridional direction and is located between 36°33' and 47°07' N latitude. and 45°43΄ and 54°03΄ E (without Kara-Bogaz-Gol Bay). The length of the sea along the meridian is about 1200 km; the average width is 310 km. The northern coast of the Caspian Sea is bordered by the Caspian lowland, the eastern coast by the deserts of Central Asia; in the west, the mountains of the Caucasus approach the sea, in the south, near the coast, the Elburz ridge stretches.

The surface of the Caspian Sea is much lower than the level of the World Ocean. Its current level fluctuates around -27 ... -28 m. These levels correspond to the sea surface area of 390 and 380 thousand km 2 (without the Kara-Bogaz-Gol Bay), the volume of water is 74.15 and 73.75 thousand km 3, average depth is about 190 m.

The Caspian Sea is traditionally divided into three large parts: the North (24% of the sea area), the Middle (36%) and the South Caspian (40%), which differ significantly in morphology and regime, as well as the large and isolated Kara-Bogaz-Gol Bay. The northern, shelf part of the sea is shallow: its average depth is 5–6 m, maximum depths are 15–25 m, and the volume is less than 1% of the total water mass of the sea. The Middle Caspian is a separate basin with the area of maximum depths in the Derbent depression (788 m); its average depth is about 190 m. In the South Caspian, the average and maximum depths are 345 and 1025 m (in the South Caspian depression); 65% of the water mass of the sea is concentrated here.

There are about 50 islands in the Caspian Sea with a total area of approximately 400 km2; the main ones are Tyuleniy, Chechen, Zyudev, Konevsky, Dzhambaysky, Durneva, Ogurchinsky, Apsheronsky. The length of the coastline is approximately 6.8 thousand km, with islands - up to 7.5 thousand km. The shores of the Caspian Sea are diverse. In the northern and eastern parts, they are quite strongly indented. There are large bays Kizlyarsky, Komsomolets, Mangyshlaksky, Kazakhsky, Kara-Bogaz-Gol, Krasnovodsky and Turkmensky, many bays; off the western coast - Kyzylagach. The largest peninsulas are Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak, Krasnovodsky, Cheleken and Apsheronsky. The most common banks are accumulative; areas with abrasion shores are found along the contour of the Middle and South Caspian.

More than 130 rivers flow into the Caspian Sea, the largest of which is the Volga. , Ural, Terek, Sulak, Samur, Kura, Sefidrud, Atrek, Emba (its runoff enters the sea only in high-water years). Nine rivers have deltas; the largest are located at the mouths of the Volga and Terek.

The main feature of the Caspian Sea, as a drainless reservoir, is instability and a wide range of long-term fluctuations in its level. This most important hydrological feature of the Caspian Sea has a significant impact on all its other hydrological characteristics, as well as on the structure and regime of river mouths, on coastal zones. In the Caspian Sea level varied in the range of ~200 m: from -140 to +50 m BS; in from -34 to -20 m BS. From the first third of the 19th century and until 1977, sea level dropped by about 3.8 m - to the lowest point in the last 400 years (-29.01 m BS). In 1978–1995 The level of the Caspian Sea rose by 2.35 m and reached -26.66 m BS. Since 1995, a certain downward trend has dominated - to -27.69 m BS in 2013.

During major periods, the northern shore of the Caspian Sea shifted to Samarskaya Luka on the Volga, and perhaps even further. At maximum transgressions, the Caspian turned into a sewage lake: excess water flowed through the Kuma-Manych depression into the Sea of Azov and further into the Black Sea. In extreme regressions, the southern coast of the Caspian Sea was shifted to the Apsheron threshold.

Long-term fluctuations in the level of the Caspian are explained by changes in the structure of the water balance of the Caspian Sea. The sea level rises when the incoming part of the water balance (primarily river runoff) increases and exceeds the outgoing part, and decreases if the inflow of river waters decreases. The total water flow of all rivers averages 300 km 3 /year; while the five largest rivers account for almost 95% (the Volga provides 83%). During the period of the lowest sea level, in 1942–1977, the river flow was 275.3 km 3 / year (of which 234.6 km 3 / year is the flow of the Volga), precipitation - 70.9, underground flow - 4 km 3 /year, and evaporation and outflow to the Kara-Bogaz-Gol Bay - 354.79 and 9.8 km 3 /year. During the period of intensive sea level rise, in 1978-1995, respectively, 315 (Volga - 274.1), 86.1, 4, 348.79 and 8.7 km 3 / year; in the modern period - 287.4 (Volga - 248.2), 75.3, 4, 378.3 and 16.3 km 3 / year.

The intra-annual changes in the level of the Caspian Sea are characterized by a maximum in June–July and a minimum in February; the range of intra-annual level fluctuations is 30–40 cm. Surge-surge level fluctuations are manifested throughout the sea, but they are most significant in the northern part, where, with maximum surges, the level can rise by 2–4.5 m and the edge “retreat” by several tens of kilometers inland, and in case of surges - to drop by 1–2.5 m. Seiche and tidal level fluctuations do not exceed 0.1–0.2 m.

Despite the relatively small size of the reservoir in the Caspian Sea, there is strong excitement. The highest wave heights in the South Caspian can reach 10–11 m. Wave heights decrease from south to north. Storm waves can develop at any time of the year, but more often and more dangerously in the cold half of the year.

The Caspian Sea is generally dominated by wind currents; nevertheless, runoff currents play an appreciable role on the estuarine coasts of large rivers. Cyclonic water circulation prevails in the Middle Caspian, and anticyclonic circulation in the South Caspian. In the northern part of the sea, the patterns of wind currents are more irregular and depend on the characteristics and variability of the wind, bottom topography and coastlines, river runoff and aquatic vegetation.

The water temperature is subject to significant latitudinal and seasonal changes. In winter, it varies from 0–0.5 o C at the ice edge in the north of the sea to 10–11 o C in the south. In summer, the water temperature in the sea averages 23–28 o C, and in shallow coastal waters in the Northern Caspian it can reach 35–40 o C. At depths, a constant temperature is maintained: deeper than 100 m it is 4–7 o C.

In winter, only the northern part of the Caspian Sea freezes; in severe winter - the entire Northern Caspian and the coastal zones of the Middle Caspian. Freezing in the Northern Caspian lasts from November to March.

The salinity of water changes especially sharply in the northern part of the sea: from 0.1‰ on the estuarine coasts of the Volga and Urals to 10–12‰ on the border with the Middle Caspian. In the Northern Caspian, the temporal variability of water salinity is also great. In the middle and southern parts of the sea, salinity fluctuations are small: it is mainly 12.5–13.5‰, increasing from north to south and from west to east. The highest water salinity is in the Kara-Bogaz-Gol Bay (up to 300‰). With depth, the salinity of water increases slightly (by 0.1–0.3‰). The average salinity of the sea is about 12.5‰.

More than a hundred species of fish live in the Caspian Sea and the mouths of the rivers flowing into it. There are Mediterranean and Arctic invaders. The object of fishing is goby, herring, salmon, carp, mullet and sturgeon fish. The latter number five species: sturgeon, beluga, stellate sturgeon, spike and sterlet. The sea is capable of producing up to 500-550 thousand tons of fish annually if overfishing is not allowed. Of the marine mammals, the endemic Caspian seal lives in the Caspian Sea. Every year 5-6 million waterfowl migrate through the Caspian region.

The economy of the Caspian Sea is connected with oil and gas production, shipping, fishing, extraction of seafood, various salts and minerals (Kara-Bogaz-Gol Bay), with the use of recreational resources. The explored 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 and gas are being produced on an ever-increasing scale. The Caspian Sea is also used by water transport, including along the river-sea and sea-river routes. The main ports of the Caspian Sea: Astrakhan, Olya, Makhachkala (Russia), Aktau, Atyrau (Kazakhstan), Baku (Azerbaijan), Nowshahr, Bender-Enzeli, Bender-Torkemen (Iran) and Turkmenbashi (Turkmenistan).

The economic activity and hydrological features of the Caspian Sea create a number of serious environmental and water management problems. Among them: anthropogenic pollution of river and sea waters (mainly with oil products, phenols and synthetic surfactants), poaching and reduction of fish stock, especially sturgeons; damage to the population and coastal economic activity due to large-scale and rapid changes in the level of the reservoir, the impact of numerous hazardous hydrological phenomena and hydrological and morphological processes.

The total economic damage for all the Caspian countries associated with the rapid and significant recent rise in the level of the Caspian Sea, the flooding of part of the coastal land, the destruction of coasts and coastal structures, was estimated at 15 to 30 billion US dollars. It took urgent engineering measures to protect the coast.

A sharp drop in the level of the Caspian Sea in the 1930s–1970s. led to less damage, but they were significant. The navigable approach channels became shallow, the shallow seashore at the mouths of the Volga and the Urals became heavily overgrown, which became an obstacle to the passage of fish into the rivers for spawning. It was necessary to build fish passages through the seasides mentioned above.

Among the unresolved problems is the lack of an international agreement on the international legal status of the Caspian Sea, the division of its water area, bottom and subsoil.

The Caspian Sea is the object of many years of research by specialists from all the Caspian states. Such domestic organizations as the State Oceanographic Institute, the Institute of Oceanology of the Russian Academy of Sciences, the Hydrometeorological Center of Russia, the Caspian Research Institute of Fisheries, the Faculty of Geography of Moscow State University, etc. took an active part in the study of the Caspian Sea.