Lake types. Glacial lakes of Russia

Origin lake basins
Sedimentation in lakes

lakes – natural reservoirs with stagnant or low-flowing water, formed as a result of flooding of land depressions (hollows) with water masses. Lakes have no connection with the ocean and, unlike rivers, have a slow water exchange.

Each lake consists of three interconnected natural components:

1. hollows - landforms of the earth's surface,
2. water mass with substances dissolved in it,
3. plants and animals that inhabit the water.

Origin of lake basins

Lake basins arise as a result of various relief-forming processes and are divided into several groups according to their origin.

The manifestation of endogenous activity is associated with the formation of tectonic and volcanic basins.

Basins of tectonic origin formed as a result of the movement of parts of the earth's crust. Many lakes that have arisen in basins of tectonic origin occupy a vast area, are characterized by great depth and have ancient age. Characteristic examples of lakes belonging to this group are the Great African Lakes (including Tanganyika with a depth of -1470 m), confined to the East African rift system, where the processes of stretching and subsidence of the continental crust take place. Lake Baikal in Russia (which is the largest freshwater reservoir and has a maximum depth of -1620 m among lakes), Lake Biwa in Japan (famous for freshwater pearls mined in it) and others have a similar origin. Basins are often confined to isometric troughs (Chad, Eyre) or large tectonic faults. Formation is also associated with tectonic processes. residual lakes, which are the remains of ancient oceans and seas. Thus, the Caspian Lake separated from the Mediterranean and Black Seas as a result of tectonic movements of the earth's crust.

Hollows volcanic origin confined to craters and calderas extinct volcanoes or located among the frozen lava fields. In the latter case, lake basins are formed when hot lava flows from under a colder surface lava horizon, which contributes to the subsidence of the latter (this is how Yellowstone Lake was formed), or when rivers and streams are dammed by lava or mud flow during volcanic eruptions. Basins of this origin are found in areas of modern or ancient volcanic activity (Kamchatka, Transcaucasia, Iceland, Italy, Japan, New Zealand, etc.).

The variety of exogenous processes leads to the formation various groups lake basins.

A large number of lake basins have glacial origin. Their formation may be associated with the activity of mountain and lowland glaciers. In the mountains, glacial lake basins are represented by moraine-dammed and cirque. Moraine-dammed ones are formed when river valleys are dammed up by glaciers. When the cirque basins are filled with water, small picturesque lakes with clean and cold water.
On the plains of the basin glacial origin distributed in the territory subjected to the Quaternary glaciation. Among them, one can distinguish hollows of exaration, glacial-accumulative and moraine-dammed origin. Exaration basins are associated with mined-out moving ice by negative relief forms. A famous example of a lake that owes its origin to the destructive activity of glaciers is Loch Ness in Scotland, formed in a glaciated river valley. Thousands of lakes formed in the basins of glacial ploughing, are found on the territory of the Scandinavian Peninsula, in northern Canada. Glacial-accumulative basins are formed in the area of ​​development of moraine deposits. Lake basins in the area of ​​the moraine-plain relief are wide, have an oval shape and shallow depth (Chudskoye, Ilmen); in the conditions of a hilly-recessional and hilly-ridged relief, they have an irregular shape, islands, and a complex coastline, dissected by peninsulas and bays (Seliger). Moraine-dammed basins arise when a moraine pre-glacial river valley is dammed up (for example, Lake Saimaa in Finland).

In areas of permafrost, basins of thermokarst origin, which owe their origin to the melting of fossil ice and frozen rocks and subsidence of the soil. Many basins of tundra lakes have this origin. All of them have a small depth and are small in area. Another area of ​​development of thermokarst basins is the area of ​​distribution of Quaternary fluvioglacial deposits. Here, during the melting of ice caps, huge blocks of dead ice turned out to be buried under a layer of sediments carried out by melted glacial waters. Many of them melted only after hundreds of years, and in their place there were basins filled with water.

Lake basins of karst origin are formed in areas composed of soluble (karst) rocks. The dissolution of rocks leads to the formation of deep, but usually insignificant basins. Here, failures often occur due to the collapse of the vaults of underground karst cavities. Examples of karst basins are the famous "Failure" in Pyatigorsk (known from the novel by Ilf and Petrov "The Twelve Chairs") and Lake. Zhirot in french alps, having a depth of -99 m with an area of ​​​​only 57 hectares.

Lake basins of suffusion origin are formed during subsidence of soils due to the removal of loose silt particles by groundwater. Basins of this genesis are found in the steppe and semi-desert zones of Central Asia, Kazakhstan and the West Siberian Plain.

Basins of fluvial origin associated with the geological activity of rivers. Most often these are oxbow and deltaic lakes. Sometimes the formation of lakes is due to the obstruction of the riverbed by alluvial sediments of another river. For example, the formation of Lake St. Croy (USA) is associated with the damming of the river. St. Croy alluvial deposits of the river. Mississippi. Due to the dynamism of erosive and accumulative fluvial processes and the small size of basins, the latter are relatively quickly filled with sediment and overgrown in some places and re-formed in others.

Some lake basins are formed as a result of springing by landslides, mountain landslides or mudflows of rivers. Usually such lakes do not exist for long - there is a breakthrough of sediments that form a "dam". So, in 1841. The Indus in present-day Pakistan was dammed by a landslide caused by an earthquake, and six months later the "dam" collapsed, and a lake 64 km long and 300 m deep was drained in 24 hours. Lakes in this group can remain stable provided that excess water is drained through erosion-resistant hard rock. For example, Lake Sarez, formed in 1911 in the valley of the river. Murghab in the Eastern Pamirs still exists and has a depth of -500 m (the tenth deepest lake in the world).
The process of damming the river with a powerful collapse also contributed to the formation of one of the "pearls" of the Caucasus - Lake Ritsa in Abkhazia. A giant landslide on the slope of Mount Pshegish dammed the Lashipse River. The waters of the river flooded the gorge (tracing a large tectonic fault in the strata of rocks) for more than 2 km, the water rose by 130 m. A river with a different name, Yupshara (in Abkhazian “split”), is knocked out from under a natural stone dam.

lakes artificial origin associated with the filling of artificial basins (quarries, etc.) with water, or with the damming of river flows. During the construction of dams, reservoirs of various sizes are formed - from small ponds to huge reservoirs (located in Africa are the Victoria reservoirs on the Victoria Nile River, Volta on the Volta River and Kariba on the Zambezi River; the largest in terms of volume in Russia is the Bratsk reservoir on the river Angara). Some dams were built to generate electricity for aluminum smelting from large deposits of bauxite. It should be added that dams are created not only by man. Dams built by beavers can reach lengths of more than 500 m, but they exist only for a short time.

Basins of coastal marine origin formed mainly as a result of the separation sea ​​bays bars from the sea area during the movement of the alongshore sediment flow. On initial stage the basin is filled with salty sea waters, and later the formed salt lake is gradually desalinated.

Hollows of organogenic origin occur in the sphagnum swamps of the taiga, forest-tundra and tundra, as well as on coral islands. In the first case, they owe their origin to the uneven growth of mosses, in the second - to coral polyps.

Lakes on the scale of geological time exist for a relatively short time. The only exceptions are some lakes with basins of tectonic origin, confined to active zones of the earth's crust, and large residual lakes. Over time, the basins are filled with sediments or become swampy.

Sedimentation in lakes

Lake deposits are represented by terrigenous, chemogenic and organogenic sediments. The composition of sediments accumulating in lakes is primarily determined by climatic zoning.

In the lakes of humid regions, predominantly silt-clay deposits accumulate, often with big amount organics. Dead organisms, as well as material carried into the lake, are deposited at the bottom and form gyttia(from Swedish gyttja - silt, mud) - lake deposits, consisting of organic residues. The organic matter of gyttium is formed mainly due to the decay products of plant and animal organisms living in water, to a lesser extent due to the remains of terrestrial plants brought from the surrounding land. The mineral part consists of sandy-clay material and oxides of calcium, iron and magnesium precipitated from water. Gyttia is also called sapropel(from the Greek sapros - rotten and pelos - silt, mud - "putrefactive silt"). In Lake Nero, located near the city of Rostov-Yaroslavsky (Rostov Veliky), the layer of sapropel reaches 20 m. Sapropels are used as fertilizer or as a mineral feed for livestock; sometimes for balneological purposes (mud therapy).

In semi-desert and desert arid zones, lakes are endorheic with intense evaporation. Since rivers and underground waters always bring salts, and only pure water evaporates, there is a gradual increase in the salinity of lake waters. The concentration of salts can increase so significantly that from the water (brine) supersaturated with salts, salt is deposited on the bottom of the lake (self-settling lakes). Salinization of continental lakes accumulates carbonate, soda, sulfate, salt and other chemogenic deposits. In Russia, modern soda lakes are known in Transbaikalia and Western Siberia; abroad, Lake Natron in Tanzania and Lake Searls in California are very famous. Natural soda deposits are associated with fossil deposits of such lakes.
In general, arid regions are characterized by halogen-carbonate deposits, poor in organic matter.

In a number of cases, the origin of lake basins plays a decisive role in the nature of sedimentation. Glacial lakes are characterized by banded clays formed by a combination of lacustrine and glacial deposits. In karst lakes, carbonates accumulate, sometimes heaps of blocks of landslide origin.

Familiarization with varieties, geographical location, temperature regime of waters and chemical composition of lakes in Russia.

Study of the location, area and depth indicators of the largest domestic reservoirs - Baikal, Ladoga and Onega lakes.

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Significant water reserves are concentrated in lakes. There are more than 2.5 million lakes in Russia. The largest lakes are the Caspian, Ladoga, Onega and Baikal.

The Caspian Lake is the largest lake in the world, the deepest is Lake Baikal. The lakes are very unevenly distributed.

In particular, in the Vilenovsky basins, the West Siberian Plain and the northwestern layer of Europe - in Karelia. All these areas are in too much humidity. In the south, in the zone of the steppe and semi-sedimentary zone with a weak climate, the number of lakes decreases sharply, and many lakes have salt or salt. Salt is such huge large lakes as the Caspian, as well as lakes Elton and Baskunchak, where salt is eliminated.

Hydrographic characteristics of large lakes in Russia

Eat different lakes and the origins of the basins.

Lakes of tectonic origin are located in trenches and cracks in the earth's crust. The largest tectonic lake Baikal is located in the Graben, reaching a depth of 1637 m.

Ice-tectonic lake basins were created as a result of processing liquid depressions of the glacial crust of the glacier: Imandra, Ladoga, Onega.

In Kamchatka and the Kuril Islands, the lake is mainly of volcanic origin. In the northwest of the European Plain, the sources of lake basins are connected with continental ice. Many caves are located between the hills of the sea: Seliger, Valdai.

Due to landslides in mountain valleys there was a lake of a lake: Sarez in the Pamirs, Ritsa in the Caucasus. Small lakes are formed by karst nests.

In the south of Western Siberia, there are many lakes in the form of plates, which were created as a result of stoning stones. When ice melts on the surface of the permafrost, shallow slab-like waters also form. Lake people are located on the flood plains of low-lying rivers. On the Black and Sea of ​​Azov there are estuary lakes.

All the largest and largest lakes in Russia are often used in the national economy. Catch and catch in them. Especially a lot of fish, including the most valuable sturgeon, end up in the Caspian.

In Baikal, the harvest is omul. Lakes are also used for navigation - geoglobus.ru. Numerous minerals were acquired in the lakes of lakes: oil and mirbilite in the Caspian lake, salt in Elton and Baskunchak. Water for freshwater lakes is used for drinking. There are many sanatoriums and rest houses on the shores of many lakes.

There are nine lake districts on the territory of Russia:

1) northwestern lake, iceberg iceberg;
2a) Azov-Black Sea estuaries associated with marine activities;
2b) North Caucasian-glacial and karst lake;
3) salt formation of the Caspian Lake;
4) West Siberian-Tuscan and bitter-salty lakes;
5) Altai - sea view of lakes (Teletskoye, Markakol);
6) Zabaikalsky - the remaining lakes;
7) Lower Amur lakes, which have a hydrological connection with the Amur River;
8) Yakuti - lakes of thermocouples;
9) Lake Kamchatka - lakes of volcanic origin (Kronotsky, Kurilsky).

They are formed in places of faults and shifts of the earth's crust. As a rule, these are deep narrow reservoirs with straight sheer banks, located in deep through gorges. Kurile Lake is located in the south of Kamchatka in a deep picturesque basin surrounded by mountains. The greatest depth of the lake is 306 m. Its banks are steep. Numerous mountain streams flow from them. The lake is sewage, the Ozernaya River originates from it. Hot springs come to the surface along the shores of the lake, and in its middle there is an island called the Heart-stone. Not far from the lake there is a unique outcrop of pumice stones, which are called Kutkhin Baty. Currently, the lake has been declared a nature reserve and a zoological monument of nature.

bottom profile tectonic lakes sharply defined, has the form of a broken curve. Glacial deposits and processes of sediment accumulation have little changed the clarity of the tectonic lines of the lake basin.

As a result of the movement of the earth's crust, depressions form in some places over time. It is in these recesses that tectonic lakes. The three largest lakes in Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul were formed tectonically.

There are many lakes in the forest-steppe Trans-Urals. Here are such large reservoirs as Uelgi, Shablish, Argayash, B. Kuyash, Kaldy, Sugoyak, Tishki, etc. The depths of the lakes on the Trans-Ural Plain noticeably decrease and do not exceed 8-10 m. By origin, these lakes belong to the erosion-tectonic type. Tectonic depressions were modified as a result of the impact of erosion processes. Many lakes of the Trans-Urals are confined to ancient hollows of river flow (Etkul, Peschanoe, Alakul, Kamyshnoe, etc.).

Characteristics of lakes

After a long study of the lakes, scientists have identified a number of characteristics inherent in this type of water bodies.

1. Water surface area.
2. Length coastline.
3. The length of the lake To measure this, the two most remote points of the coastline are taken. During the measurement, the average width is determined - this is the ratio of area to length.
4. The volume of the basin, which is filled with water, is determined.
5. Installed average depth reservoir, the maximum depth is also determined.

The largest lake in the world is the Caspian, and the deepest is Baikal.

Origin of lakes

All existing lakes divided into underground and surface. The basins themselves can be of endo- and exogenous origin. This factor determines the shape and size of the reservoir. Tectonic lakes are located in the largest basins. They can be located in tectonic depressions, like Ilmen, in grabens (Baikal), or in foothill and mountain foredeep.

Most of the large basins have a complex tectonic origin. Discontinuous, folded movements participated in their formation. All tectonic lakes are different large size and significant depths, the presence of rocky slopes. The bottom of most reservoirs is located at the level of the World Ocean, and the mirrors are much higher.

Some regularity can be traced in the location of tectonic lakes: they are concentrated along the faults of the earth or in rift zones, but they can frame shields. Examples of such lakes are Ladoga and Onega, located along the Baltic Shield.

Lake types

There is a classification of lakes according to the water regime.

1. Drainless. Rivers flow into these types of reservoirs, but none of them flows out. Most of them are located in areas with insufficient humidity: in the desert, semi-desert. This type includes the Caspian Sea-Lake.
2. Waste. Rivers flow into these lakes, and they also flow out of them. Such species are most often found in the zone of excessive moisture. A different number of rivers flow into such lakes, but usually only one flows out. An example of a tectonic lake of a sewage type is Baikal, Teletskoye.
3. Flowing reservoirs. Many rivers flow into and out of these lakes. Examples are lakes Ladoga and Onega.

In any reservoir, food occurs due to precipitation, rivers, and underwater resources. Partially, water evaporates from the surface of reservoirs, flows out or goes underground. Due to this feature, the amount of water in the pool fluctuates. For example, Chad covers an area of ​​about twelve thousand square kilometers during a drought, but during the rainy season, the basin covers an area twice as large - about 24 thousand square kilometers.

tectonic lakes

The largest lakes in the world are of tectonic origin. Baikal, Ladoga and Onega lakes can be an example. Endogenous factors play an important role in the origin of tectonic lakes. The basins of these reservoirs are formed on the sunken parts of the earth's crust. Typically, such basins are strongly elongated and deep.

Baikal

The deepest and largest lake in the world fresh water. Baikal is located in Siberia. The area of ​​this basin is more than 31 thousand square kilometers, the depth is over 1500 meters. If you look at Baikal in terms of water volume, then it takes only the second place after the Caspian Sea-lake. The water in Baikal is always cold: in summer - about nine degrees, and in winter - no more than three. The lake has twenty-two islands: the largest is Olkhon. 330 rivers flow into Baikal, but only one flows out - the Angara.

Baikal influences the climate of Siberia: it softens winters and makes summers cooler. average temperature in January - about -17 °С, and in summer +16 °С. In the south and in the north, a different amount of precipitation falls throughout the year - from 200 to 900 mm. From January to May Baikal is covered with transparent ice. This is due to very clean and transparent water - you can see everything that happens in the water at a depth of up to forty meters.

Other types of reservoirs

There are glacial-tectonic lakes that have arisen as a result of the processing of tectonic depressions in the earth's crust by glaciers. Examples of such lakes are Onega, Ladoga. There are volcanic lakes in Kamchatka and the Kuriles. There are lake basins that appeared due to continental glaciations.

In the mountains, some lakes were formed due to blockages, for example, Lake Ritsa in the Caucasus. Small reservoirs arise above karst failures. There are saucer-shaped lakes that arise on loose rocks. Melting permafrost can form shallow lakes.

Lakes of glacial-tectonic origin are located not only in the mountains, but also on the plains. The waters fill the hollows, literally plowed by glaciers. During the movement of the glacier from the northwest to the southeast along the cracks, the ice, as it were, made a furrow. It filled with water: this is how many reservoirs were formed.

Ladoga lake

One of the largest glacial-tectonic lakes is Ladoga. It is located in the Leningrad region and in Karelia.

The area of ​​​​the lake is more than seventeen thousand square kilometers: the width of the reservoir is almost 140 kilometers, and the length is 219 km. The depth throughout the entire basin is uneven: in the northern part it ranges from eighty to two hundred meters, and in the south - up to seventy meters. Ladoga is fed by 35 rivers, and only one - the Neva - takes its beginning.

There are many islands on the lake, among which the largest are Kilpola, Valaam, Mantinsari.

Lake Ladoga freezes in winter and opens in April. The water temperature on the surface is uneven: in the northern part it is about fourteen degrees, and in the south - about twenty degrees.

The water in the lake is hydrocarbonate type with weak mineralization. It is clean, transparency reaches seven meters. Throughout the year there are storms (they are strongest in autumn), calm (most often in summer).

Onega and other lakes

Most of the islands Onega Island A: there are more than a thousand of them. The largest of them is Klimetsky. More than fifty rivers flow into this reservoir, and only the Svir takes its beginning.

There are many tectonic lakes in Russia, among which there is a drainage basin, including Ilmen, Saima, Lake Onega.

There are lakes of similar origin in Krasnaya Polyana, for example Khmelevsky. Their formation was served by a deflection that arose in the process of destruction of the earth's crust. The deflections that appeared as a result of this led to the formation of basins that were filled with water. As a result, Khmelevsky lakes were formed in this place, which became a national park. There are four large lakes and several small reservoirs, swamps.

Large lakes located on the territory of Russia have a large economic importance. These are huge reserves of fresh water. Navigation is developed in the waters of many large lakes. On the shores there are recreation centers, equipped fishing spots. In very large lakes, such as Ladoga, fishing is carried out.

Tectonic lakes of Russia on News4Auto.ru.

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- a reservoir formed on the surface of the land in a natural depression. Since the lake has no direct connection with the ocean, it is a reservoir of slow water exchange.

The total area of ​​lakes on the globe is about 2.7 million km 3, which is 1.8% of the land surface.

The main characteristics of the lake:

• lake area - water surface area;
• coastline length - water edge length;
• lake length - shortest distance between the two most distant points on the coastline, average width - ratio of area to length;
• lake volume - the volume of the basin filled with water;
• average depth - ratio of water mass volume to area;
• maximum depth - found by direct measurements.

The largest lake in terms of water surface area on Earth is the Caspian (376 thousand km 2 at a water level of 28 m), and the deepest is Baikal (1620 m).

Characteristics largest lakes the world are given in table. 1.

In each lake, three interconnected components are distinguished: the basin, the water mass, the vegetation and fauna of the reservoir.

Lakes of the world

By position lake basin lakes are divided into ground and underground. The latter are sometimes filled with juvenile water. The subglacial lake in Antarctica can also be classified as an underground lake.

Lake basins can be like endogenous, and exogenous origin, which most significantly affects their size, shape, water regime.

The largest lake basins. They can be located in tectonic depressions (Ilmen), in foothill and intermountain troughs, in grabens (Baikal, Nyasa, Tanganyika). Most of the large lake basins have a complex tectonic origin, both discontinuous and folded movements are involved in their formation (Issyk-Kul, Balkhash, Victoria, etc.). All tectonic lakes are large, and most of them have significant depths, steep rocky slopes. The bottoms of many deep lakes lie below the level of the World Ocean, and the mirror of the oxen is above the level. Certain regularities are observed in the location of tectonic lakes: they are concentrated along the faults of the earth's crust, either in rift zones (Syrian-African, Baikal), or frame shields: along the Canadian shield, there are Bolshoi Bear Lake, the Great Slave, the Great North American Lakes, along the Baltic Shield - Onega, Ladoga, etc.

Volcanic lakes occupy craters and calderas of extinct volcanoes (Kronopkoye Lake in Kamchatka, lakes of Java, New Zealand).

Along with the lake basins created internal processes Earth, very numerous lake baths formed due to exogenous processes.

Among them, the most common glacial lakes on the plains and in the mountains, located both in hollows plowed by the glacier, and in depressions between hills with uneven deposition of moraine. The destructive activity of ancient glaciers owes its origin to the lakes of Karelia and Finland, which are elongated in the direction of glacier movement from northwest to southeast along tectonic cracks. In fact, Ladoga, Onega and other lakes have a mixed glacial-tectonic origin. The glacial basins in the mountains include numerous, but small car lakes located in bowl-shaped depressions on the slopes of mountains below the snow line (in the Alps, in the Caucasus, Altai), and trough lakes - in trough-shaped glacial valleys in the mountains.

Lakes among hilly and moraine relief are associated with uneven accumulation of glacial deposits on the plains: in the northwest of the East European Plain, especially on the Valdai Upland, in the Baltic States, Poland, Germany, Canada and in the north of the USA. These lakes are usually shallow, wide, with lobed shores, with islands (Seliger, Valdai, etc.). In the mountains, such lakes arose on the site of former tongues of glaciers (Como, Garda, Würm in the Alps). In areas of ancient glaciation, there are numerous lakes in the hollows of the flow of melted glacial waters, they are elongated, trough-shaped, usually small and shallow (for example, Dolgoye, Krugloye - near Moscow).

Karst lakes are formed in places where rocks are leached by underground and partly surface waters. They are deep, but small, often rounded in shape (in the Crimea, the Caucasus, in the Dinaric and other mountainous regions).

Suffusion lakes are formed in basins of subsiding origin at the site of intensive removal of fine earth and mineral particles by groundwater (south of Western Siberia).

Thermokarst Lakes are created when permafrost is burned or ice melts. Thanks to them, the Kolyma Lowland is one of the most lake regions in Russia. Many relict thermokarst lake basins are located in the northwest of the East European Plain in the former periglacial zone.

eolian lakes arise in blowout basins (Lake Teke in Kazakhstan).

Zaprudnye lakes are formed in the mountains, often after earthquakes, as a result of landslides and landslides blocking river valleys (Lake Sarez in the Murgab valley in the Pamirs).

In the valleys of lowland rivers, the most numerous are floodplain oxbow lakes of a characteristic horseshoe shape, formed as a result of meandering of rivers and subsequent straightening of channels; when rivers dry up in bochagas - reaches, river lakes are formed; in river deltas there are small ilmen lakes, in place of channels, often overgrown with reeds and reeds (ilmens of the Volga delta, lakes of the Kuban floodplains).

On the low coasts of the seas, coastal lakes are characteristic in place of estuaries and lagoons, if the latter are separated from the sea by sandy alluvial barriers: spits, bars.

A special type are organogenic lakes among swamps and coral buildings.

These are the main genetic types of lake basins, determined by natural processes. Their location on the continents is presented in Table. 2. But recently, more and more "man-made" lakes created by man have appeared - the so-called anthropogenic lakes: lakes - reservoirs on rivers, lakes - ponds in quarries, in salt mines, on the site of peat mining.

By genesis of water masses There are two types of lakes. Some have water of atmospheric origin: precipitation, river and groundwater. Such lakes insipid, although in dry climates they can eventually become salty.

Other lakes were part of the World Ocean - these are relic salty lakes (Caspian, Aral). But even in such lakes, the primary sea water can be greatly transformed and even completely displaced and replaced by atmospheric water (Ladoga and others).

Table 2. Distribution of the main genetic groups of lakes by continents and parts of the world

depending from water balance, t.s. According to the conditions of inflow and runoff, lakes are divided into waste and non-drainage. Lakes that discharge part of their waters in the form of river runoff - sewage; a special case of them are flowing lakes. Many rivers can flow into the lake, but only one flows out (the Angara from Lake Baikal, the Neva from Lake Ladoga, etc.). Lakes that do not have a runoff into the oceans - drainless(Caspian, Aral, Big Salt). The water level in such lakes is subject to fluctuations of different duration, which is primarily due to long-term and seasonal climate changes. At the same time, the morphometric characteristics of lakes and the properties of water masses change. This is especially noticeable on lakes in arid regions, which are predicted to have long cycles of humidification and aridity of the climate.

The waters of the lakes, like others natural waters, are characterized by different chemical composition and varying degrees mineralization.

According to the composition of salts in the water, the lakes are divided into three types: carbonate, sulfate, chloride.

By degree of mineralization lakes are divided into insipid(less than 1% o), brackish(1-24.7% s), salty(24.7-47% o) and mineral(more than 47% c). Baikal can serve as an example of a fresh lake, the salinity of which is 0.1% c \ brackish - the Caspian Sea - 12-13% o, the Big Salt - 137-300% o, the Dead Sea - 260-270% o, in some years - up to 310% s.

In the distribution of lakes with varying degrees of mineralization on the earth's surface, geographical zoning is traced, due to the coefficient of moisture. In addition, those lakes into which rivers flow are distinguished by low salinity.

However, the degree of mineralization can be different within the same lake. So, for example, in the endorheic Lake Balkhash, located in the arid zone, in the western part, where the river flows into. Or, the water is fresh, and in the eastern part, which is connected to the western part only by a narrow (4 km) shallow strait, the water is brackish.

When the lakes are oversaturated from the brine, the salts begin to precipitate and crystallize. Such mineral lakes are called self-planting(for example, Elton, Baskunchak). Mineral lakes in which lamellar fine needles are deposited are known as mud.

plays an important role in the life of lakes thermal regime.

Fresh lakes of the hot thermal zone are characterized by the warmest water near the surface, with depth it gradually decreases. This distribution of temperature over depth is called direct thermal stratification. Lakes of the cold thermal zone have the coldest (about 0 ° C) and light water at the top for almost the entire year; with depth, the water temperature rises (up to 4 ° C), the water becomes denser, heavier. This distribution of temperature over depth is called reverse thermal stratification. Lakes of the temperate thermal zone have a variable stratification according to the seasons of the year: direct in summer, reverse in winter. In spring and autumn there come moments when the vertical temperature is the same (4 °C) at different depths. The phenomenon of temperature constancy over depth is called homothermy(spring and autumn).

Annual thermal cycle in lakes temperate zone is divided into four periods: spring heating (from 0 to 4 °С) is carried out due to convective mixing; summer heating (from 4 °C to maximum temperature) - by molecular heat conduction; autumn cooling (from maximum temperature to 4 °C) - by convective mixing; winter cooling (from 4 to 0 ° C) - again by molecular heat conduction.

In the winter period of freezing lakes, the same three phases are distinguished as in rivers: freezing, freezing, opening. The process of formation and melting of ice is similar to rivers. The lakes are usually covered with ice for 2-3 weeks longer than the rivers of the region. The thermal regime of freezing salt lakes resembles that of the seas and oceans.

Dynamic phenomena in lakes include currents, waves and seiches. Stock currents occur when a river flows into a lake and outflow of water from the lake into the river. In flowing lakes, they can be traced throughout the entire water area of ​​the lake, in stagnant lakes - in areas adjacent to the mouth or source of the river.

The height of the waves on the lake is less, but the steepness is greater compared to the seas and oceans.

The movement of water in lakes, along with dense convection, contributes to the mixing of water, the penetration of oxygen into the lower layers, and the uniform distribution of nutrients, which is important for a wide variety of lake inhabitants.

By nutritional properties of the water mass and the conditions for the development of life, lakes are divided into three biological types: oligotrophic, eutrophic, and dystrophic.

Oligotrophic- low-nutrient lakes. These are large deep transparent lakes with greenish-blue water, rich in oxygen, so organic residues are intensively mineralized. Due to the small amount of biogenic elements, they are poor in plankton. Life is not rich, but there are fish, crustaceans. It's many mountain lakes, Baikal, Geneva, etc.

Eutrophic lakes have a high content of nutrients, especially nitrogen and phosphorus compounds, are shallow (up to 1015 m), well heated, with brownish-green water. The oxygen content decreases with depth, which is why fish and other animals die in winter. The bottom is peaty or silty with an abundance of organic remains. In summer, there is a "bloom" of water due to the strong development of phytoplankton. The lakes are rich in flora and fauna. They are most common in forest-steppe and steppe zones.

Dystrophic lakes are poor in nutrients and oxygen, they are shallow. The water in them is acidic, slightly transparent, brown due to the abundance of humic acids. The bottom is peaty, there are few phytoplankton and higher aquatic vegetation, animals too. These lakes are common in heavily wetlands.

In the last decade, under the conditions of increased supply of phosphorus and nitrogen compounds from the fields, as well as the discharge of wastewater from some industrial enterprises, eutrophication of lakes has been observed. The first sign of this unfavorable phenomenon is a strong bloom of blue-green algae, then the amount of oxygen in the reservoir decreases, silts form, and hydrogen sulfide appears. All this will create unfavorable conditions for the life of fish, waterfowl, etc.

The evolution of lakes occurs in different ways in wet and dry climates: in the first case, they gradually turn into swamps, in the second, into salt marshes.

In a humid (humid) climate, the leading role in filling the lake and turning it into a swamp belongs to vegetation, partly to the remains of the animal population, which together form organic remains. Temporary streams and rivers bring mineral deposits. Small lakes with gently sloping shores are overgrown by pushing vegetative ecological zones from the periphery to the center. Eventually the lake becomes a grassy fens.

Deep lakes with steep banks overgrow in a different way: by growing from above alloys(quick) - a layer of living and dead plants. It is based on plants with long rhizomes (cinquefoil, watch, calla), and other herbaceous plants and even shrubs (alder, willow) settle on a grid of rhizomes. The raft first appears near the coast, protected from the wind, where there is no excitement, and gradually moves towards the lake, increasing in power. Part of the plants dies, falls to the bottom, forming peat. Gradually, only “windows” of water remain in the quagmire, and then they disappear, although the basin is not yet filled with sediments, and only with time does the raft merge with a layer of peat.

In dry climates, lakes eventually become salt marshes. This is facilitated by an insignificant amount of precipitation, intense evaporation, a decrease in the inflow of river waters, and the deposition of solid sediments brought by rivers and dust storms. As a result, the water mass of the lake decreases, the level decreases, the area decreases, the concentration of salts increases, and even a fresh lake can first turn into a salt lake (Great Salt Lake in North America), and then to the salt marsh.

Lakes, especially large ones, have a softening effect on the climate of the surrounding areas: it is warmer in winter and cooler in summer. So, at coastal weather stations near Lake Baikal, the temperature in winter is 8-10 °С higher, and in summer by 6-8 °С lower than at stations outside the influence of the lake. The air humidity near the lake is higher due to increased evaporation.

A lake is a body of water with slow water exchange. Lakes are classified according to various criteria: in origin (tectonic, volcanic, dammed, glacial, sinkhole, karst, etc.); by salinity (fresh, brackish, saline, brine, etc.); by trophicity (oligotrophic, mesotrophic, eutrophic, etc.); by position in the landscape (lowland, floodplain, highland, etc.); by depth (shallow, deep, super-deep); by morphology (rounded, elongated, ribbon-shaped, crescent-shaped, bead-shaped, etc.); by flow (non-drainage, low-flow, periodically flow-through, temporary, relict); by types of use (fishery, for water supply, for the extraction of salt, sapropel ore, therapeutic mud and so on.); according to condition (clean, polluted, overgrown, etc.). How long do lakes live? Most often, it is relatively short - a few thousand or tens of thousands of years. This applies primarily to glacial and oxbow lakes. Karst, volcanic and especially tectonic lakes can exist for millions and tens of millions of years. For example, one of the lakes in Australia was formed about 700 million years ago. How many lakes are on earth? An exact count has not yet been made. There are probably about 2 million lakes in Canada and Alaska, about 100 thousand in Finland and the Scandinavian Peninsulas. About 100 thousand in Great Britain and Ireland as well as Denmark, Belgium, Holland and France. Hydrologists believe that there are about 5 million lakes on the earth. Tectonic lakes. They are formed in places of faults and shifts of the earth's crust. As a rule, these are deep narrow reservoirs with straight sheer banks, located in deep through gorges. Kurile Lake is located in the south of Kamchatka in a deep picturesque basin surrounded by mountains. The greatest depth of the lake is 306 m. Its banks are steep. Numerous mountain streams flow from them. The lake is sewage, the Ozernaya River originates from it. Hot springs come to the surface along the shores of the lake, and in its middle there is an island called the Heart-stone. Not far from the lake there is a unique outcrop of pumice stones, which are called Kutkhin Baty. At present, the lake has been declared a reserve and a zoological monument of nature. The profile of the bottom of tectonic lakes is sharply outlined, looks like a broken curve. Glacial deposits and processes of sediment accumulation have little changed the clarity of the tectonic lines of the lake basin. The influence of the glacier on the formation of the basin can be noticeable, it leaves traces of its presence in the form of scars, sheep's foreheads, which are clearly visible on the rocky shores and islands. The shores of the lakes are composed mainly of hard stone rocks that are weakly susceptible to erosion, which is one of the reasons for the weak process of sedimentation. These lakes belong to the group of lakes of normal depth (a=2-4) and deep (a=4-10). The deep-water zone (more than 10 m) of the total volume of the lake is 60-70%, shallow water (0-5m) 15-20%. The waters of the lakes are thermally heterogeneous: during the period of the greatest heating of surface waters, low bottom temperatures remain, which is facilitated by stable thermal stratification. Aquatic vegetation is rare, only in a narrow strip along the shores of closed bays. Typical lakes in the river basin. The suns are large and medium-sized: Palye, Sundozero, Sandal, as well as very small lakes Salvilambi and Randozero, located on private watersheds of lakes Palye and Sandal. As a result of the movement of the earth's crust, depressions form in some places over time. It is in these depressions that tectonic lakes arise. The three largest lakes in Kyrgyzstan: Issyk-Kul, Son-Kul and Chatyr-Kul were formed tectonically. There are many lakes in the forest-steppe Trans-Urals. Here are such large reservoirs as Uelgi, Shablish, Argayash, B. Kuyash, Kaldy, Sugoyak, Tishki, etc. The depths of the lakes on the Trans-Ural Plain noticeably decrease and do not exceed 8-10 m. By origin, these lakes belong to the erosion-tectonic type. Tectonic depressions have been modified as a result of the impact of erosion processes. Many lakes of the Trans-Urals are confined to ancient hollows of river flow (Etkul, Peschanoe, Alakul, Kamyshnoe, etc.). Lake Baikal. General information Lake Baikal Baikal is a freshwater lake in the south of Eastern Siberia, it stretches from 53 to 56°N. and from 104 to 109°30’ E Its length is 636 km and the coastline is 2100 km. The width of the lake varies from 25 to 79 km. The total area of ​​the lake (mirror area) is 31,500 sq. km. Baikal is the deepest lake in the world (1620 m). It contains the largest reserves of fresh water on earth - 23 thousand cubic kilometers, which is 1/10 of the world's fresh water reserves. A complete change of such a huge amount of water in Baikal takes 332 years. This is one of the oldest lakes, its age is 15 - 20 million years. 336 rivers flow into the lake, including the Selenga, Barguzin, Upper Angara, and only one Angara flows out. Baikal has 27 islands, the largest of which is Olkhon. The lake freezes in January, opens in May. Baikal lies in a deep tectonic depression and is surrounded by taiga-covered mountain ranges; the area around the lake has a complex, deeply dissected relief. Near Baikal, the band of mountains expands noticeably. The mountain ranges here stretch parallel to one another in the direction from the northwest to the southeast and are separated by hollow-shaped depressions, along the bottom of which rivers flow and in some places there are lakes. The height of most of the ridges of Transbaikalia rarely exceeds 1300 - 1800, but the highest ridges reach high values. For example, xr. Khamar-Daban (top of Sohor) - 2304 m, and Barguzinsky ridge. about 3000 m. Tectonic movements continue here even now. This is evidenced by frequent earthquakes in the region of the basin, outcrops of hot springs, and, finally, subsidence of significant sections of the coast. The waters of Lake Baikal have a blue-green color, are distinguished by exceptional purity and transparency, often even greater than in the ocean: you can clearly see stones lying at a depth of 10-15 m and thickets of greenish algae, and a white disk lowered into the water is visible at a depth of 40 m. Baikal lies in the temperate zone. Geography of Lake Baikal Lake Baikal is located in the south of Eastern Siberia. In the form of a crescent being born, Baikal stretched from southwest to northeast between 55°47" and 51°28" north latitude and 103°43" and 109°58" east longitude. The length of the lake is 636 km, the maximum width in the central part is 81 km, the minimum width opposite the Selenga delta is 27 km. Baikal is located at an altitude of 455 m above sea level. The length of the coastline is about 2000 km. The area of ​​the water mirror, determined at the water's edge of 454 m above sea level, is 31,470 square kilometers. The maximum depth of the lake is 1637 m, the average depth is 730 m. 336 permanent rivers and streams flow into Baikal, while half of the water entering the lake comes from the Selenga. The only river flowing from Baikal is the Angara. However, the question of the number of rivers flowing into Baikal is rather controversial, most likely there are fewer than 336. There is no doubt that Baikal is the deepest lake in the world, the closest contender for this title, the African Lake Tanganyika, lags behind by as much as 200 meters. There are 22 islands on Baikal, although, as mentioned above, there is no unanimity on this issue. The largest island is Olkhon. Age of Lake Baikal The age of the lake is usually given in the literature as 20-25 million years. In fact, the question of the age of Baikal should be considered open, since the use of various methods for determining the age gives values ​​from 20-30 million to several tens of thousands of years. Apparently, the first estimate is closer to the truth - Baikal is indeed a very ancient lake. It is believed that Baikal arose as a result of the action of tectonic forces. Tectonic processes are still going on, which is manifested in the increased seismicity of the Baikal region. If we assume that the age of Baikal is indeed several tens of millions of years, then this is the oldest lake on Earth. Origin of the name Numerous scientific studies have been devoted to the problem of the origin of the word "Baikal", which indicates a lack of clarity in this matter. There are about a dozen possible explanations for the origin of the name. Among them, the most probable is the version of the origin of the name of the lake from the Turkic-speaking Bai-Kul - a rich lake. Of the other versions, two more can be noted: from the Mongolian Baigal - a rich fire and Baigal Dalai - a large lake. The peoples who lived on the shores of the lake called Baikal in their own way. Evenks, for example, - Lamu, Buryats - Baigal-Nuur, even the Chinese had a name for Baikal - Beihai - the North Sea. The Evenk name Lamu - the Sea was used for several years by the first Russian explorers in the 17th century, then they switched to the Buryat Baigal, slightly softening the letter "g" by phonetic replacement. Quite often, Baikal is called the sea, simply out of respect, for its violent temper, for the fact that the far opposite shore is often hidden somewhere in the haze... At the same time, the Small Sea and the Big Sea are distinguished. The Small Sea is what is located between the northern coast of Olkhon and the mainland, everything else is the Big Sea. Baikal water Baikal water is unique and amazing, like Baikal itself. It is unusually transparent, pure and saturated with oxygen. In not so ancient times, it was considered healing, with its help, diseases were treated. In spring, the transparency of Baikal water, measured using the Secchi disk (a white disk with a diameter of 30 cm), is 40 m (for comparison, in the Sargasso Sea, which is considered the standard of transparency, this value is 65 m). Later, when a massive algae bloom begins, the transparency of the water decreases, but in calm weather, the bottom can be seen from a boat at a fairly decent depth. This high transparency is due to the fact that Baikal water, due to the activity of living organisms living in it, is very weakly mineralized and close to distilled. The volume of water in Baikal is about 23 thousand cubic kilometers, which is 20% of the world's fresh water reserves. Climate The climate in Eastern Siberia is sharply continental, but the huge mass of water contained in Baikal and its mountainous surroundings create an unusual microclimate. Baikal works like a big thermal stabilizer - it is warmer in winter and slightly cooler in summer than, for example, in Irkutsk, located at a distance of 60 km from the lake. The temperature difference is usually around 10 degrees. A significant contribution to this effect is made by forests growing on almost the entire coast of Lake Baikal. The influence of Lake Baikal is not limited to the regulation of the temperature regime. Due to the fact that the evaporation of cold water from the surface of the lake is very small, clouds cannot form over Baikal. In addition, the air masses that bring clouds from the land heat up when passing the coastal mountains, and the clouds dissipate. As a result most time over Baikal the sky is clear. This is also evidenced by the numbers: the number of hours of sunshine in the region of Olkhon Island is 2277 hours (for comparison - on the Riga seashore 1839, in Abastumani (Caucasus) - 1994). You should not think that the sun always shines over the lake - if you are not lucky, then you can run into one or even two weeks of disgusting rainy weather even in the sunniest place of Baikal - on Olkhon, but this is extremely rare. The average annual water temperature on the surface of the lake is +4°C. Near the coast in summer the temperature reaches +16-17°C, in shallow bays up to +22-23°C. Wind and waves The wind blows almost always on Baikal. More than thirty local names of winds are known. This does not mean at all that there are so many different winds on Baikal, just that many of them have several names. Peculiarity Baikal winds in that almost all of them almost always blow along the coast and there are not as many shelters from them as we would like. Prevailing winds: northwest, often called mountain winds, northeast (barguzin and verkhovik, also known as angara), southwest (kultuk), southeast (shelonnik). Max Speed wind, registered on Baikal, 40 m/s. Large values ​​are also found in the literature - up to 60 m/s, but there is no reliable evidence for this. Where there is wind, there, as you know, there are waves. I note right away that the opposite is not true - the wave can be even with complete calm. Waves on Lake Baikal can reach a height of 4 meters. Sometimes values ​​​​of 5 and even 6 meters are given, but this is most likely an estimate "by eye", which has a very large error, as a rule, in the direction of overestimation. The height of 4 meters was obtained using instrumental measurements in the open sea. The excitement is strongest in autumn and spring. In the summer on Lake Baikal, strong excitement is rare, and calm often occurs.

Hello dear readers! Now I will tell you about what lakes are and about their main types.

- these are natural reservoirs in the depressions of the land (hollows), filled within the lake bowl (lake bed) with a heterogeneous water mass.

Lack of direct connection with the World characteristic of lakes. The area occupied by the lakes is about 2.1 million km 2 or almost 1.4% of the land area, which is almost seven times the surface of the big lake in the world - the Caspian Sea (424,300 km 2).

Lakes are unevenly distributed: in the north there are especially many of them - in the forest zone and tundra, less often lakes are found in the south, in the desert and in the steppe.

Lake types.

Lakes can have different origins. Geographers classify lakes according to the presence of life, the content of salts, and the way they are formed. There is no life only in the most salty lakes. Most of the lakes were formed as a result of volcanic eruptions or movements.

Also, lakes can form in depressions that have arisen as a result of the uneven distribution of glaciers in areas of continental icing. (moraine and glacial lakes); when ice melts in subsidence dips (thermokarst lakes); in castrate abysses and funnels (fire lakes); in valleys blocked by collapse, glacier or displacement (volcanic lakes of Java, the Kuril Islands, etc.), by applying a mule or sand (estuary lakes of the Crimean Peninsula).

Many lakes were created by people. These lakes are called reservoirs, since they contain a reserve of water for hydroelectric power stations and other economic needs.

Let us consider in more detail the main types of lakes:

Tectonic lakes. These lakes are the most interesting. They occur in places of tectonic faults, as a rule, they are very deep and have an elongated shape.

The deepest lake in the world is Baikal (max. depth - 1620 m, average - 730 m), tectonic in origin. It arose as a result of a break in the block of the earth's crust, as a result of which a depression filled with water appeared.

Due to the formation of the water mass of lakes. Sometimes sea ​​water, which in the geological past filled the basin, is replaced by fresh water. These are the so-called relic lakes , including Onega, Lake Ladoga and the Aral with the Caspian Seas.

The reasons for the formation of the Caspian Sea (the largest lake on Earth) are faults and folds, due to the movement of the earth's crust.

In the depression between the Mangyshlak plateau in the East and Caucasus mountains in the West, the Caspian Sea is located. Its dimensions have been constantly changing over the past few million years.

The Caspian Sea connected with the Black Sea before the Caucasus Range rose.

Another example of a huge fault is the East African Rift System. It is filled with a chain of lakes and extends from Southeast Africa to the North to Southwest Africa. The most famous of the lakes of this system are Nyasa (Malawi), Albert, Tanganyika, Edward.

On the territory of Israel, but the same system belongs to the lowest-lying lake in the world - the Dead Sea (-399 m, below sea level).

Lakes can also sewage(from them flow, or their flow may be underground) and drainless(they do not have drains, they are mainly found in deserts and semi-deserts).

The endorheic Lake Chany is very interesting, it is prone to abrupt changes in boundaries, depending on fluctuations in annual or seasonal rainfall. Nomadic lakes include: Chad, Lop Nor and Eyre.

The hydrological and thermal regimes of lakes are not as pronounced as those of rivers, due to the large volume of water.

During the period of floods and floods, there are no such impressive rises of water on the lakes, and freezing and ice drift occur more slowly than in rivers. But there are lakes strong winds, including seiches.

freshwater lakes they feed on rainwater, streams and rivers, but minerals and soils that are washed off the banks gradually accumulate with a limited supply of fresh water. The fresh water evaporates and the mineral-rich brine remains in the lake.

Salt lakes. More-less, endorheic lakes mineralized, they accumulate salts (from 1 to 24.7% - brackish lakes, and from 24.7 to 47% - salty), which are located even in the fresh water of their tributaries.

There are also mineral lakes (they contain more than 47% of salts), including flowing ones, they are formed due to the flow of mineralized waters from the depths of the Earth. Salts from them may precipitate.

The Aral and Caspian Seas are salt lakes. The Aral Sea was the fourth largest lake in the world, but after the channels of the rivers replenishing it were changed, it began to dry up.

The area of ​​the sea has decreased from 77,451 km 2 to 40,000 km 2, and this gives reason to talk about the gradual death of the lake.

The Dead Sea is the saltiest lake. It is located in the Jordan Valley between Jordan and Israel. Its water is 9 times saltier than ocean water. As a result of this, the density of water is so high that on its surface you can lie quietly, as if on a bed, and read a newspaper.

Volcanic lakes. A water-filled volcanic crater is the most common form of volcanic lake.

Crater Lake in Mazama Volcano Crater, Oregon () – one example of this type of lake. This lake has a diameter of 10 km and a depth of 598 m, and was formed 6600 years ago.

Some lakes were formed when lava flows blocked volcanic valleys and water accumulated in them. Lake Kivu is such an example, a depression in the East African Rift System on the border between Rwanda and Zaire.

Once flowing from Lake Tanganyika, the Ruzizi River flowed through the Kivu Valley north to the Nile, but after a nearby volcano erupted, which blocked the river's course, its waters filled the depression.

In the northern hemisphere, the most common lakes were created by glaciers during the last ice age. This is how the lakes of the Italian Alps, about 60,000 Finnish lakes and most of the British lakes were formed.

After themselves, the glaciers left deep depressions in which accumulated warm water. Moraine (glacial deposits) dammed depressions, forming lakes. An example is the reservoirs of the Lake District in the North of England.

Lakes can also form underground, in limestone voids. Water dissolves limestone, creating water-filled huge caves. Similar lakes can form in areas of underground salt deposits.

artificial lakes. The most famous example of artificial lakes are reservoirs. Among the largest are Lake Mead in the USA, which appeared after the damming of the Colorado River, and Lake Nasser on the border of Sudan and Egypt, which was created by damming the Nile Valley.

All of them serve hydroelectric power stations. Also, many artificial lakes exist for industrial use and to provide water to large settlements. Another example of artificial lakes is decorative small lakes created in parks or just at home in the yard.

Such lakes serve as a decoration, an outdoor aquarium for fish and just a place for birds to take a bath 🙂

These were the main types of lakes, I hope this information will be useful to you 🙂

The largest lakes in the world

* Unstable area