General notion

Morphometric characteristics. By unique and rather rich natural resources an internal pool of our planet - the Caspian Sea - is situated on border of two large parts of unified continent Eurasia, and the waters wash shores of five states: Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan.

Offshore line of these states along coast Caspian following: Azerbaijan - 850, Iran - 900, Kazakhstan - 2320, Russia - 695 and Turkmenistan – 1200 km.

The Caspian Sea is prorated in meridian direction in the form of the Latin "S" character and is disposed between 470 07 and 360 33 northern latitudes and 450 43 and 540 03 eastern longitudes. Extension of the sea along a meridian about 1200 km, average width is 310 km, and greatest and least width are 435 and 196 km, accordingly. Below than level of the World Ocean and at such level its floor space is 392600 km2, and volume of waters 78648 km3.
The Caspian Sea - deep-water pool with a hardly developed shelf zone. On value of maximum depth of 1025 m. the Caspian Sea concedes only to two most steep lakes of a world about. Of Baikal (1620 m) and about Tanganica (1435 m). The average depth of the sea designed on an area depth distribution curve, is peer 208 m. The distribution curve of a volume of waters Caspian on depth displays, that the considerable proportion of waters 62 % - lays within the limits of plutonic zones from 100 up to 600 m. On a share of dominating depths of water of -0-100 m - it is necessary 25,7 % of a volumes of waters. In zones of depths more than 800 m the volume of waters compounds only 16%.
The shelf of the Caspian Sea is on average limited to depths about 100 m. The continental slope, which starts below that edge of shelf, is ended in the middle part approximately at depths of 500-600 m., in the southern part, where it is very steep - 700-800 m.
In the western coast the shelf is narrow, average width is 40 km. In the southern coast it is much more narrower, where the depths is about 400 m, it is 5-6 km from the coast. In the eastern coast the shelf is vaster, average width is about 130 km.
Proceeding from features of a morphological constitution and physic-geographic conditions, the Caspian Sea is accepted for dividing into three parts: Northern, Middle and South Caspian. For conditional border between Northern and Middle Caspian is usually taken a line connecting isle Cheleken from c. Tub-karagan, and between Middle and South Caspian a line between isle Zhiloi-cape Kuuli. As natural border North and Middle Caspian disjoints Мangishlak threshold extended in the form of a shallow water (depth up to 10 m), from a peninsula Tub-Karagan to bank Кulalinskoi and further to a peninsula Chechen. Middle and South Caspian disjoints the Apsheron threshold. This underwater asymmetric elevation goes from peninsula Apsheron to the Cheleken peninsula.
The total area of the North Caspian is 91942 km2, its water area is 90129 km2. Share of North Caspian is more than 24,3 % of the floor space of all sea. Areas of Middle and South Caspian are almost equal. The general floor space of the Middle Caspian is 137812 km2, South - 148640 km2. Or accordingly 25.788 m. and 1029 m, average depths 4.4, 192 and 345 m.

The beaches of the Caspian sea differ by diversity. In northern part they are hardly desected. Kizlar, Astrakhan, Маngishlac and set of shallow-water bays are disposed there. Noticeable peninsulas - Аrhanskii, Buzagi, Тub-Karagan, Mangishlac. Large islands in northern part of the sea - Tulenii, Кulali. In deltas of Volga and Ural the shore line is trimmed by a set of island regions and passages frequently changing the position.
The middle part of the sea has rather flat coastline. On the western coast on border with a southern part of the sea is disposed Apsheron peninsula. To the east of the island and banks of Apsheron archipelago can be observed the largest islands Pirallahi and Zhiloi. Eastern beach of the Middle Caspian is more desected, the Kazakh bay with a bay Kinderly and some capes are located there: Sandy, Rakushechniy, and Sua. The largest bay of this coast is Kara-Bogaz Gol.

To the south of Аpsheron coast the islands of Baku archipelago are located: the Bulla, Los, Duvanii, Svinoi, Vulf etc. The genesis of these islands, and also some banks at the eastern coast of a southern part of the sea (Livanov, Zhdanov etc.) is linked with activity of underwater mud volcanoes in the bottom of the sea. On the eastern coast the large bays - Krasnovodskii and Тurkmenskii, and in the vicinity of it - island Ogurchinskii are located.
According to its geographic arrangement the Caspian sea can be called the climatic indicator of the huge area of a planet the Earth. A drainage basin of the sea, the area which is 3.5 million km2, is located within the limits of Azerbaijan, Kazakhstan, Iran and Turkey. More than 130 rivers fall into the Caspian Sea. Among them of the greatest importance is Volga. The second place is taken by the river Kura.
Relief of coasts and bottom. Northern Caspian frames pri-Caspian lowland. It is a new Caspian plane with marine traces of terraces of different levels of stand of the sea. The rivers and temporary water, falling into the Caspian Sea, have predetermined progressing here of delta forms of the relief, most considerable of which - delta of Volga and Ural.
Northern coast of the Caspian Sea differs by small slopes of underwater coast slope and coastal land. Typical for beaches of North Caspian is also availability of a zone of drying formed under the influence of phenomena of wave motions, and also great dinamics of shoreline as a result of sea level fluctuation.
The Dagestan coast of the Caspian Sea is narrow flatness derived by terraces at water boundary, the terraces of New Caspian age. To the south of delta of r. Samur the beach of the sea becomes steep, in shoulder of the whole crop pebbly alluvial deposits composing a part of the lowland are stripped.

The coast of Kislar region differs by originality of a construction of a relief. Here to the sea go anticline zones of the Greater Caucasus; coast lowland is narrowed up to 1-2 km. And in a relief the influence of native patterns predominates. The most of coastal plane is formed by a Khvalyn terraces.
Coastal line of the western coast of the sea on a whole is smooth, except for the Аpsheron peninsula. Series of anticlinal uplifts with synclinal lowerings, dividing them there. That creates the desected character of the coastal line.

To the south of c. Pirsagat the coastal plane is depressed and passes in broad New Caspian terrace, the monotony of which one is broken by mud volcanoes, coastal bars and separate dunes. A large morphological element of the coastal line of southwest area in the South Caspian – is the delta of Kura river, which sharply protrudes towards the sea.
The coast located to the south of Lenkoran lowland represents marine plane joining the modern beach. From the west the plane is limited by a sandy-shelly coastal bars.

Within the limits of the Iranian coast mountain hills of Elbrus system close approach to the coast of the sea, leaving only narrow (2-40 km) line of accumulative plane that is very weakly declined to the north.
Eastern beach of the Middle Caspian from Tub-Karagan till the – Kara-bogaz gol has abrasion nature. To the south of Kenderly spit are the beach becomes steep, predominantly abrasion. Within the Western - Turkmenish lowland the coastal zone is composed of New Caspian deposits. Along the coast high sandy-shelly bars occurs framed by a line of drying from the sea. Behind the arbor the saline former scuttlebutts, taken from the sea in New Caspian time place.
According to the nature of a bottom relief the northern part of the Caspian Sea is gentle, shallow-water plane with numerous islands, terraces, old channels of the rivers.
In the relief of the floor of the Middle Caspian the main morphological elements can be observed: shelf, slope, and bed of the basin. Eastern part of the Middle Caspian is located in the Epigertsian platform, and western part and area adjacent to Apsheron to a threshold - in the Alpine geosynclinal area. The bottom relief of the Southern Caspian is characterized by a big complicity.

Climatic and hydrological characteristics.
The climatic performances above the aquatorium of the Caspian Sea and its coast develop under effect of global atmospheric processes, domestic air circulation and distorting influence of the landscape, main of which are the mountains of Caucasus, Elbrus, Kopet-dag, desert of Central Asia etc.

In different seasons of year weather conditions of Caspian are influenced by the invasion of air masses formed above the Arctic Ocean, Northern Atlantic, Mediterranean Sea, Western Siberia bringing rainfalls and clouds or other aerosol inclusions. This is the way of formation of regimes of cloudiness, temperature and humidity of air, direction and velocity of winds, component of radiation balance, disturbance, flow, temperature of water, transparency of water and air, etc.
The Caspian Sea influences atmospheric processes and climate of surrounding land. Annual balance of the sea shows some warming that is the greatest in the Southern and Northern parts of the sea and in the Apsheron peninsula. In the middle part warming effect in the winter is replaced by cooling effect in the summer.

The direction and force of winds blowing above the Caspian Sea, is determined by three factors: general atmosphere circulation parameter, field of temperature created by the sea, and contour of its shores.
The general regularity of wind mode is that most of the year there exist winds of northern (NW, N, NE) and southeast directions. The average speed of a wind within the aquatorium is 5,7 m/s. The maximum annual speeds are observed in the middle part of the sea and on average they are 6-7 m/s . In the Apsheron peninsula is 8-9 m/s. The northwest winds, dominant in the sea, are of the northern direction and the velocities are of 25-30 m/s. The location of the Caspian Sea in different climatic zones causes major distinctions in distribution of temperature of air over the sea. Annual average variation is from 10C0 in the northern part of the sea up to 17C0 in the southern. The coldest month is January, the warmest - July and August.

Distribution of rainfalls in the aquatorium of the sea is extremely irregular. In the western coast of the southern part of the sea it varies from 65 (Petroleum Rocks) up to 1250 mms. annually (Lenkoran zone). Eastern coast differs by dryness; the maximum amount of rainfall does not exceed 15-20m. On the Iranian coast with a wet climate up to 1000-2000 rainfalls annually fall annually.
Circulation of waters. The general circulation of waters of the Caspian sea can be described as follows. In the North Caspian the drain of the river Volga is dual. One part is directed to southwest and goes along western coast of the Middle Caspian. The second part turns to northwest and following along northern, eastern, southern coast of the Northern Caspian, and form in the southeast part anticyclone (directed clockwise) circulation of water.

Further waters from the North Caspian go to the Middle Caspian and being displaced along western shore streamline Apsheron peninsula, following then to the south and further, turning according to a configuration of beach to the east.
Temperature of water. Because of a rather tension of the sea in the meridian temperature of water is exposed to considerable latitude variations most clearly expressed in a winter period, when temperature varies from 0 -0,50C at the ice edge. In the north of the sea it is up to 10 -11, in the south, the difference of temperature of water is about 100C. In the summer this difference is reduced up to 1 –20C, the relative horizontal uniformity is formed: in the north -24 – 250C, in the south - 25 – 260C. Temperature near the eastern coast is 1 – 20C lower, than near the western coast.

Salinity of water is changed dramatically in northern part of the sea: from 0,1 % in areas of Volga and Ural till 10-11 % on border with the Middle Caspian. In the middle and southern parts of fluctuations of salinity are insignificant: 12,6 - 13,0 %.
Ice Formation. For northern part of the sea the ice formation in November is characteristic. The occurrence of ice in the middle and southern parts of the sea falls to December - January, sometimes to February. The vanishing of an ice cover is usually observed in the second half of February - March.

Sea level fluctuations are typical for Caspian. During the historical time the amplitude of sea level fluctuation was about 15m. From the beginning of our century up to the 1978 sea level up lowered to a mark -29,0 m аbs. And the general reduction was 3,2 m. For a period of 1978-1975 the sea level rised by 2,50 m and at the end of the period it was 26,52 m. аbs. Since 1996 a new reduction of the level of the Caspian Sea has been recorded.
Run-off - surge fluctuations of level are well expressed in the northern part of the sea. Here at maximum surges the level can be increased by 2,0 - 4,5 m. during run-offs, can be depressed decreased by 1,0 - 2,5 m. In the middle and the southern parts of the sea run-off - surge of fluctuation of level is less: 60 - 70 cm.

Tidels in the Caspian are practically absent. The flows in the sea are of the wind nature. In the Caspian the main surges of eastern and southeast directions exist. Most typical for the sea are the altitudes of surges observed in the territory adjacent to the Apsheron peninsula. Very seldom it is possible to expect a surge more than 10m high.

13.04.2011     Print  Print