Lakes classification and origin

The lake is a closed indentation of land,filled with water. It has a slow water exchange, unlike rivers, and does not flow into the waters of the oceans, unlike seas. These bodies of water on our planet are distributed unevenly. The total area of ​​the Earth’s lakes is about 2.7 million km², or about 1.8% of the land surface.

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

Lakes classification by origin

Glacial reservoirs formed due to meltingglaciers. It happened during periods of extreme cold snaps, which have held down the continents several times over the past 2 million years. The glacial periods resulted in modern lakes located in North America and Europe, namely in Canada, Baffin Land, Scandinavia, Karelia, the Baltic States, the Urals, and other places.

Huge blocks of ice under the weight of their weight, andalso, because of their movements, they formed considerable trenches in the thickness of the earth's surface, sometimes even moved apart tectonic plates. In these pits and rifts after the melting of the ice and formed reservoirs. One of the representatives of the glacial lakes can be called oz. Arbersee

Причиной возникновения тектонических озер стали movements of lithospheric plates, resulting in the formation of faults in the crust. They began to fill with water from the melting glaciers, which led to the emergence of this type of reservoir. The brightest example is Lake Baikal.

River lakes appear when occursdrying of some sections of the flow rivers. In this case, the formation of chained reservoirs arising from a single river. The second option of river formations are floodplain lakes, which appear because of water barriers that interrupt the water course.

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

Карстовые озера представляют собой земные ditches that are filled with the waters of underground rivers. The pits are the dips of the lithosphere, consisting of rocks of limestone. Due to the failure, limestone rocks line the bottom of the reservoir, which affects the transparency of its water: it is 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.

Mountain lakes are located in mountain basins.They are formed in several ways. Due to the mountain landslides that block the river flow and thus form lakes. The second method of formation is the slow gathering of huge blocks of ice, which leave behind them deep dips of the land - hollows, which are filled with waters from the melted ice.

Volcanic lakes appear in the craterssleeping volcanoes. Such craters have significant depth and high edges, which prevents runoff and tributaries of river water. This makes the volcanic lake practically isolated. Craters are filled with rainwater. The specific location of such objects is often reflected in the composition of their waters. Increased carbon dioxide content makes them dead, unfit for life.

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

Above was compiled a classification of lakes depending on the origin.

Types of lakes by location

To make a classification of lakes depending on the position in relation to the land, can be as follows:

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

Mineralization classification

To make a classification of lakes by the number of salts, you can:

1. Fresh lakes are formed from rainwater,melted glaciers, groundwater. The waters of such natural objects do not contain salts. In addition, freshwater lakes are the result of overlapping river beds. The largest freshwater lake is Baikal.
2. Salt ponds are divided into brackish and salty.

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

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

Chemical Classification

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

1. In carbonate lakes, an increased concentration of Na and Ca. From the depths of such bodies of water is mining soda.
2. Sulfate lakes are considered therapeutic due to the content of Na and Mg in them. In addition, sulphate lakes are the place where Glauber's salt is mined.
3. The chloride lakes are salt lakes, which are the place of extraction of the common table salt.

Water balance classification

1. Sewage lakes are endowed with river runoffthe discharge of a certain amount of water. As a rule, such reservoirs have several rivers flowing into their basin, but the stream that flows is always the same. A great example is the large lakes - Lake Baikal and Teletskoye. The water of sewage lakes is fresh.
2. The drainless lakes are salt lakes, since the water flow in them is more active than its flow. They are located in the desert and steppe zones. Sometimes in them on an industrial scale is the extraction of salt and soda.

Nutrient Classification

1. Oligotrophic lakes contain relativelysmall amount of nutrients. The features are the transparency and purity of the waters, the color is from blue to green, the depth of the lakes is significant - from medium to deep, the decrease in oxygen concentration is closer to the bottom of the lake.
2. Eutrophic saturated with high concentrationnutrients. The peculiarities of such lakes are the following phenomena: the amount of oxygen abruptly decreases to the bottom, mineral salts are abundant, the color of the water is from dark green to brown, from which the transparency of the water is low.
3. Dystrophic lakes are extremely poor in minerals. The oxygen content is low, the transparency is low, the color of the water may be yellow or dark red.

Conclusion

The water basin of the Earth consists of: rivers, seas, oceans, glaciers of the world ocean, lakes. There are several types of lake classification. They were considered in this article.

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