The origin of lakes and their distribution on the globe

A lake is a natural body of land with slow water exchange. According to the nature of water exchange, lakes are distinguished:

Wastewater - i.e. dumping part of their waters in the form of river runoff (Baikal, Onega, Ladoga)

Drainless - i.e. devoid of flow. Characteristic for arid regions (Issyk-Kul, Balkhash, Chad).

Flowing - through which there is a transit flow of the river (Lake Chudskoye, Sarezskoye).

The concept of "lake" includes a hollow and a water mass that fills it as an inseparable whole. The origin of the lake is associated with the formation of a basin under the influence of endogenous and exogenous processes and its filling with water for a long time.

Lakes are ubiquitous on the land surface. There are especially many lakes in areas of ancient glaciation and permafrost (northern Europe, USA, Canada, Siberia).

176 thousand km 3 of water are concentrated in the lakes of the world, including 91 thousand km 3 of fresh water. On the globe, lakes occupy 2.1 million km 2, i.e. 1.4% sushi.

The largest lakes (by area) include: the Caspian brackish sea - 374,000 km 2 (78,200 km 3 of water), the Upper - 82,680 km 2 (Canada), Victoria - 69,000 km 2 (Tanzania), the Aral Sea - 64,100 km 2 (Kazakhstan ), Huron - 59800 km 2 (Canada, USA), Michigan - 58100 km 2 (USA) Tanganyika - 32900 km 2 (Tanzania, Zaire).

Baikal - 31500 km 2, and the volume - 23000 km 3 - the largest volume fresh water and the deepest in the world (1620m).

The best known typology of lakes is based on the nature of the origin of lake basins. The following types of lakes are distinguished:

1. Tectonic- formed in troughs of the earth's crust on the plains (Ladoga, Onega), in mountain troughs (Issyk-Kul, Balkhash), in rifts, grabens (Baikal, Tanganyika).

2. Volcanic- formed in craters, volcanic calderas (lakes of Java), in depressions of lava covers (lakes of Kamchatka, Lake Kivu in Africa).

3. Glacial- formed in relief depressions formed by the exaration and accumulative activity of sheet and mountain glaciers. They are divided into:

trough- (Lake Geneva, Karelia, Scandinavia)

car and circus(Alps, Caucasus)

moraine(northern Russia, USA, Canada)

supraglacial in the tongues of glaciers (Caucasus, Lake Como in the Alps)

4. Karst- formed in negative relief forms associated with the dissolving activity of waters (Crimea, Caucasus - Ritsa)

5. meteorite- formed as a result of the impact of space bodies (Lake Kaali in Estonia)

6. Thermokarst- formed in the active layer of permafrost (tundra, forest-tundra, northern taiga)

7. Suffusion- formed in subsidence during mechanical washing out of fine soils (West Siberia - Lake Chany)

8. River- formed as a result of water-erosion and water-accumulation activity of permanent watercourses. These include: oxbow lakes, reservoir, delta, valley reservoirs.

9. landslide-dammed- formed in the mountains as a result of the blocking of river valleys by landslide bodies (Sarez in the Pamirs, Amtkeli in the Caucasus)

10. Marine- formed as a result of detachment from the sea area by sandy deposits of parts of bays, bays, estuaries. There are estuary lakes (flooded river valleys) and lagoon lakes (areas of water area separated by bars and spits from the sea).

11. eolian- formed in the hollows of blowing and between the dunes (Lake Teke in Kazakhstan).

12. Organogenic- intramarsh lakes and lagoon lakes inside atolls.

Lakes can also be classified by size:

very big- with an area of ​​more than 1000 km 2 (Balkhash, Baikal);

large-101-1000 km 2 (Ilmen);

medium- 10-100 km 2;

small- less than 10 km2.

A lake is a closed depression of land filled with water. It has a slow water exchange, unlike rivers, and does not flow into the waters of the oceans, unlike the seas. These reservoirs on our planet are distributed unevenly. The total area of ​​the Earth's lakes is about 2.7 million km 2, or about 1.8% of the land surface.

The lakes have a number of differences among themselves both in external parameters and in the composition of the water structure, origin, etc.

Classification of lakes by origin

Glacial reservoirs were formed due to the melting of glaciers. This happened during periods of severe cooling, which fettered the continents repeatedly over the past 2 million years. The result of the ice ages were modern lakes located on the territory of North America and Europe, namely in Canada, Baffin Island, Scandinavia, Karelia, the Baltic States, the Urals and in other areas.

Huge blocks of ice, under the weight of their weight, and also because of their movements, formed considerable pits in the thickness of the earth's surface, sometimes even pushed apart tectonic plates. In these pits and faults, after the melting of ice, reservoirs were formed. One of the representatives of glacial lakes can be called Lake. Arbersee.

The cause of the occurrence was the movement of lithospheric plates, as a result of which faults were formed in the earth's crust. They began to fill with water from melting glaciers, which led to the emergence of this type of reservoir. The clearest example is Lake Baikal.

River lakes appear when some sections of flowing rivers dry up. In this case, the formation of chain reservoirs arising from one river takes place. The second variant of river formations are floodplain lakes, which appear due to water barriers that interrupt the water channel.

Seaside lakes are called estuaries. They appear when lowland rivers are flooded by the waters of the seas or as a result of the lowering of sea coasts. In the latter case, a strip of land or shallow water appears between the newly formed bay and the sea. In estuaries, which appeared from the confluence of the river and the sea, the water has a slightly salty taste.

Karst lakes are earth pits that are filled with the waters of underground rivers. Pit pits are failures of the lithosphere, consisting of limestone rocks. As a result of the failure, the bottom of the reservoir is lined, which affects the transparency of its filled waters: they are crystal clear.

Karst lakes have one distinctive feature - they are periodic in their appearance. That is, they can disappear and form again. This phenomenon depends on the level of underground rivers.

They are located in mountain valleys. They are formed in several ways. Due to mountain landslides that block the river flow and thereby form lakes. The second way of formation is a slow descent huge boulders ice, which leave behind deep land failures - basins that are filled with water from melted ice.

lakes volcanic type appear in the craters of dormant volcanoes. Such craters have a significant depth and high edges, which impede the runoff and inflow of river waters. This makes the volcanic lake practically isolated. Craters fill with rainwater. The specific location of such objects is often reflected in the composition of their waters. The increased content of carbon dioxide makes them dead, unsuitable for life.

These are reservoirs and ponds. They are created intentionally for industrial purposes. settlements. Also, artificial lakes can be the result of earthworks, when the remaining earthen pits are filled with rainwater.

Above was a classification of lakes depending on the origin.

Types of lakes by position

It is possible to make a classification of lakes depending on their position in relation to the earth as follows:

1. Terrestrial lakes are located directly on the surface of the land. These are involved in the constant water cycle.
2. Underground lakes are located in underground mountain caves.

Mineralization classification

You can classify lakes by the amount of salts as follows:

1. Fresh lakes are formed from rainwater, melting glaciers, groundwater. The waters of such natural objects do not contain salts. In addition, fresh lakes are a consequence of the overlapping of river beds. The biggest fresh lake- Baikal.
2. Salt water bodies are subdivided into brackish and saline.

Brackish lakes are common in arid areas: steppes and deserts.

Salt lakes in terms of the content of salts in the thickness of their waters resemble oceans. Sometimes the salt concentration of lakes is somewhat higher than in the seas and oceans.

Classification by chemical composition

The chemical composition of the lakes of the Earth is different, it depends on the amount of impurities in the water. Lakes are named based on this:

1. In carbonate lakes, there is an increased concentration of Na and Ca. Soda is mined from the depths of such reservoirs.
2. Sulfate lakes are considered curative due to the content of Na and Mg in them. In addition, sulfate lakes are a place for the extraction of Glauber's salt.
3. Chloride lakes are salt lakes, which are the place where common table salt is mined.

Water balance classification

1. Waste lakes are endowed with the help of which a certain amount of water is discharged. As a rule, such reservoirs have several rivers flowing into their basin, but there is always one flowing one. An excellent example is the large lakes - Baikal and Teletskoye. The water of sewage lakes is fresh.
2. Endorheic lakes are saline lakes, since the flow of water in them is more active than its inflow. They are located in the desert and steppe zones. Sometimes they produce salt and soda on an industrial scale.

Classification according to the amount of nutrients

1. Oligotrophic lakes contain a relatively small amount of nutrients. The peculiarities are the transparency and purity of the waters, the color from blue to green, the depth of the lakes is significant - from medium to deep, the decrease in oxygen concentration closer to the bottom of the lake.
2. Eutrophic plants are saturated with a high concentration of nutrients. The peculiarities of such lakes are the following phenomena: the amount of oxygen sharply decreases towards the bottom, there is an excess of mineral salts, the color of the water is from dark green to brown, which is why the transparency of the water is low.
3. Dystrophic lakes are extremely poor in minerals. There is little oxygen, the transparency is low, the color of the waters can be yellow or dark red.

Conclusion

The water basin of the Earth is made up of: rivers, seas, oceans, glaciers of the oceans, lakes. There are several types of lake classifications. They have been reviewed in this article.

Lakes, like other bodies of water, are the most important natural resources that are actively used by man in various fields.

Distribution of lakes around the world. Lake types.

Lakes are natural reservoirs, which are depressions in the earth's surface filled with water with a profile of the coastal zone developed by the influence of wind waves and currents and slow water exchange. The lake differs from the river, as a rule, by the absence of a current due to the slope of the channel, from the sea - by the absence of a two-way connection with the ocean.

Each lake consists of three mutually connected components: 1) basins - landforms of the earth's crust, 2) water and substances dissolved in it - part of the hydrosphere, and 3) plant and animal population of the reservoir - part of the living matter of the planet.

Morphometric characteristics of water bodies.

The morphometry of lakes is associated with quantitative estimates and changes in the shape of the lake and its elements. Morphometric indicators are determined according to the plan or map of the reservoir in isobaths and refer to a certain water level. Lake length L (km) - the shortest distance between the two most distant points from each other coastline a body of water measured along its surface.

Width of lake B (km): average is the quotient of dividing the area of ​​the reservoir surface F by its length; maximum width Bmax - the greatest distance between the banks along the perpendicular to the length of the reservoir.

The length of the coastline L (km) is measured along the water's edge (zero isobath). The indentation of the coastline characterizes the degree of irregularity in the outline of the coast and is defined as the ratio of the length of the coastline of the lake to the circumference of a circle with an area equal to that of the lake. The surface area (mirror) of the lake F (km2) is the area of ​​the water surface without islands. Depth: maximum Hmax (m) is found according to sounding data; average Hav (m) - is calculated as the quotient of dividing the volume of the water mass (V) by the area of ​​its mirror (F). The volume of water mass V (km3) is calculated as the sum of the volumes of individual layers enclosed between two adjacent horizontal planes drawn along isobaths. Horizontal layers are considered as truncated cones or as prisms.

Lake classification

By origin, the lakes are divided into:

Tectonic: formed by filling cracks in the earth's crust. A striking example of a tectonic lake is Lake Baikal.

Glacial: formed by a melting glacier. A typical glacial lake left from the last ice age is the Arbersee, located at the foot of the Great Arber mountain (1456 m) - the most high mountain Bohemian forest.

River (or old women).

Seaside (lagoons and estuaries). The most famous lagoon is the Venetian lagoon, located in the northern part of the Adriatic Sea.

Failed(karst, thermokarst). A feature of some failed lakes is their periodic disappearance and appearance, depending on the peculiar dynamics of groundwater. A typical representative is Lake Ertso in South Ossetia.

Volcanic: located in craters extinct volcanoes. In Europe, similar lakes are located in the Eifel region (Germany). Near them, weak manifestations of volcanic activity in the form of hot springs are observed.

Zavalno-dammed: formed during the collapse of part of the mountain (for example, Lake Ritsa in Abkhazia).

Crater.

Artificial (reservoirs, ponds). The creation of such lakes can be an end in itself, for example, to create reservoirs for various purposes. Often this creation is associated with more or less significant earthworks. But in some cases, such lakes appear as a side effect of such work, for example, in depleted quarries.

According to the position of the lake are divided into (in relation to the planet Earth):

Ground, whose waters take an active part in the water cycle in nature and groundwater, whose waters, if they take part in it, then only indirectly. Sometimes these lakes are filled with juvenile, that is, native water.

Underground. The subglacial lake in Antarctica can also be attributed to the number of underground lakes.

According to the water balance, the lakes are divided into:

sewage(have a drain, mainly in the form of a river).

Drainless(they do not have surface runoff or underground water drainage to neighboring watersheds. Water consumption occurs due to evaporation).

By type of mineralization

fresh;

ultra-fresh

mineral (salty).

brackish

salty

According to the chemical composition of water mineral lakes are divided into:

carbonate (soda)

sulfate (bitter-salty)

chloride (salty)

According to their location on celestial bodies, lakes are divided into:

earthly;

extraterrestrial.

Lake water dynamics. The movement of water in lakes ensures its mixing, therefore, promotes the spread of oxygen, aeration of the lower strata and the distribution of nutrients.

The most significant is the vertical circulation of water associated with the thermal regime. Where it does not exist, the gas regime of the lake is not favorable for life. For example, in Tanganyika there is no oxygen below the temperature jump layer, 0.9 of the volume of this lake is lifeless.

Despite the fact that lakes are reservoirs of slow water exchange, most of them have currents. Near the mouths of rivers - tributaries, inertial currents are formed, diverging like a fan and fading towards the center of the lake. Their area is proportional to the size of the flow of rivers. In flowing lakes, under the pressure of tributaries and the suction action of outflowing rivers, waste streams arise. Their volume and intensity are determined by the water balance of the lake. Yes, in lake constance, through which the Rhine flows, the current is similar to a river, only at a lower speed. The larger the volume of the lake, the relatively smaller the runoff currents; they are absent in low-flowing lakes.

Winds cause wind currents. Usually they are temporary. In large endorheic lakes, wind and inertial currents form a slow movement of water along the coast in the form of circular coastal currents, going counterclockwise in accordance with the Coriolis force.

Waves are of great importance for the thermal and gas regime of lakes. There are two types of waves in lakes: wind waves, already described in the section on the seas, and seiches. Seiches are called standing waves that occur under the influence of rapidly changing atmospheric pressure, or a blow of wind falling from the mountains, or, finally, a heavy downpour in one part of the lake. Since water is incompressible, the force applied to it causes a rocking motion: on one side the water level rises, on the other it drops, then vice versa. This is a single node seisha with one antinode. There are also two-nodal ones, with two antinodes, in the middle and near the coast.

In this article we will talk about what types of lakes are, as well as how they happened, i.e. consider the general description of the lake. A lake is an inland body of land with slow-flowing or stagnant water. It is formed at the surface of the earth in a natural depression. Since the lakes are not connected to the ocean, they are a reservoir of slow water exchange. On the planet they occupy only about 2% of the land. The largest is the Caspian Sea, and the deepest is Baikal. There are various types of lakes that are of different origin. Each body of water is distinguished by several interconnected components: a basin, a water mass, vegetation, and wildlife.

Characteristics of the lake: the origin of lake basins and types of lakes

Endogenous - most of the large lakes, which are the result of the manifestation of the internal forces of the Earth. Tectonic as well as volcanic basins are classified as endogenous basins.

Tectonic depressions are subsided zones of the earth's crust. The subsidence occurs due to the deflection of the layers (Aral) or faults along the cracks (Upper, Baikal, Huron, Michigan). Volcanic depressions are the craters of volcanoes. There are such basins in Kamchatka.

Exogenous - small types of lakes, which were formed by the activity of external forces. Often, river valleys have oxbow lakes, which have an oblong shape. They appear on the site of the former riverbeds.

Many water basins formed during the Ice Age. During their movement, the glaciers “plowed out” huge depressions that were filled with water.

Similar glacial lake characteristics can be found in the north-west of Russia, as well as Canada, Finland. Almost all of them are elongated in the direction of movement of glaciers.

Dams are the result of strong earthquakes in the mountains. So, for example, the Sarez reservoir was formed in the Pamirs (1911). During the earthquake, a part of the mountain range was thrown into the river valley, a dam was formed with a depth of more than 600 meters.

A significant number of depressions are of mixed origin. For example, Onega and Ladoga are tectonic, but the action of glaciers has modified their basins. The Caspian Sea is the remnant of a giant basin that was previously connected to the Black Sea. Hollows created by man are artificial reservoirs.

Mountain lake Ritsa (Abkhazia) has a glacial-tectonic origin

Typeslakes by water regime

1. Sewage - rivers not only flow into them, but also flow out (they may have an underground flow). The data is most often in the zone of excessive moisture. A different number of rivers flow into such lakes, but only one (Baikal, Teletskoye) flows out.

1. Endorheic - rivers flow in, none of them flows out (i.e. such lakes do not have a drain). They are located in areas of insufficient moisture (most often deserts, semi-deserts). The same type includes the Caspian Sea, the Aral Sea, and some water basins of the tundra.

1. Flowing - many rivers flow in and out (Onega and Ladoga).

Majestic Lake Baikal

The basin is fed by flowing rivers, atmospheric precipitation, and underground water resources. Some of them evaporate from the surface of water bodies, flow out, and go into the underground runoff. And depending on the balance of income and expenditure, characteristics of lakes and water levels can fluctuate and the area of ​​these water basins changes. For example, Lake Chad during a drought covers an area of ​​about 12 thousand square meters. km, during the rainy season - 26 thousand square meters. km.

Salt content

According to the number of elements dissolved in water, three types of lakes are distinguished: fresh, brackish, salty. So, fresh - salt solution is less than 1% o, brackish - more than 1% o, and salty - more than 24.7% o.

They are classified according to the method of their formation, the presence of life and the content of salts. Life is absent only in incredibly salty reservoirs.

Uyuni Salt Lake (Bolivia)

Waste and flow basins are fresh resources, since the inflow of water significantly exceeds the flow. Drainless water resources most often brackish or salty. Such reservoirs have less inflow than outflow. This increases the salinity. Salty - occupy zones of deserts and steppes. (Big Salty, Dead, Elton).

This article has reviewed the main types of lakes which are important natural resources. Some of them are saturated with the richest raw materials, such as: salt, iron ore, sapropel. Lakes are used for water supply, navigation, irrigation, fishing, obtaining a number of chemical elements and mineral salts. The lakes also serve as a wonderful place for recreation; rest houses, sanatoriums and recreation centers have been built next to them.

More details from characteristics of lakes this video will introduce you.

What is a lake? How is it different from a pond? How do they appear on Earth?

There are many miracles on our planet that we do not observe just because we are in too much of a hurry. Roads have replaced natural travel, but as soon as you stop and get out of the car, you can see a small body of water.

A few hundred years ago, there may have been a collision with a "guest" from outer space. Or there was an eruption of a supervolcano. Under our feet, nature leaves traces of the past, whether to read them or not is up to you to decide.

What is a lake and what are its features

The name of this type of reservoir in translation from the Old English language (sounds like "lacquer") is translated as a pond or pool. From other languages, it can be translated as a puddle, a stream, and even a waterway.

The main problem in the definition is the confusion of what is described here natural source fresh (salt) water with an ordinary pond. To exclude such a connection, some definitions are interpreted with the indication of the size of the source from two to five hectares.

No matter how big the lake, it has the main difference from rivers and seas is isolation. None even the most big lake does not communicate with the ocean. On the perimeter, as a rule, it is surrounded by land.

Most of the lakes on planet Earth are filled with fresh water and have a drainage system.

Reservoirs, where nature provides for the outflow of water in the form of rivers, are called wastewater. If the water balance is maintained solely by evaporation and penetration into the ground, then these are called drainless.

Lake Maline (Canada)

The largest number of lakes is located in Canada (there are about 32 thousand of them) and Russia (more than 2 million). Beautiful lake landscapes can be found in Finland (190 thousand).

In nature, there are reservoirs of artificial origin, created for Agriculture, decorative and industrial purposes.

Types and classification of lakes

Scientists classify lakes into several types.

Origin:

1. Tectonic- lakes of tectonic origin are formed as a result of deformation of the earth's crust.
   The most famous is located on the territory of our country - Lake. Baikal. This includes the lakes of the Caspian Basin. Sometimes the soil simply sags, forming thermokarst lakes.
2. Volcanic- occupying local depressions of volcanoes. For example, in craters (crater) volcanic calderas (caldera). Over time, these irregularities are filled due to natural precipitation.

   

   crater lake in Oregon

   Quite quickly, the creation process occurs due to evaporation or the release of groundwater. Sometimes both names of lakes are mixed into one. An example is Crater Lake in Oregon, in the caldera of Mount Mazama.

3. Glacial- created under the direct influence of glaciers or continental glaciers. A wide variety of glacial processes create closed basins. Subspecies - car.
   On the world map, this can be found in Antarctica - Lake Vostok.
4. floodplain- form where the sediment from the tributary blocks the main river.
   Estuary lakes Sea of ​​Azov. Sometimes large seas dry out, forming residual.
5. Landslide lakes are common mountainous areas where the earthquake took place.

   

   Lake Quake in North America

   Although landslide lakes can be large and quite deep, they are short-lived. Quake in North America, Montana.

6. Aeolian are lakes created by the wind. An example is oz. Moses Lake Washington State.
7. Coastal- are formed due to clogging of beach ridges by longline and other currents. Oz. Coastal, Kemerovo region, Russia.
8. organic- created by the actions of plants and animals.
9. Peat- this is a form of organic lake - oz. Peat, Moscow, Russia.
10. Anthropogenic- These are artificially created lakes formed by human activities. They may be the result of deliberate damming of rivers and streams.
    An example is a lake in Altai (Russia) near tourist camp"Turquoise katun".
11. meteorite- lakes created by catastrophic extraterrestrial impacts of either a meteorite or an asteroid.
    Example - oz. Yanisjarvi, Russia, Republic of Karelia.

By type of mineralization:

Nutritionally:

By chemical composition:

Characteristics of the famous lakes of the world in the table

The table shows short description famous lakes peace.

Conclusion

From the school course, it is clear to us that most of the planet is covered with water. Some of them are deep lakes (like Baikal), some are shallow and very salty (like Sol-Iletsk). But any of them is a beautiful creation of the material world of the Earth, which sometimes tells us that nature is the most talented architect of the world in which we live.