Surface waters are an essential component of the water cycle in the troposphere. Only 0.7% of the Earth’s water is fresh and occurs in the form of lakes, rivers, aquifers and steam. In this article, we will refer to lakes. We speak of a lake when we refer to fresh or salt water, more or less extensive, retained on dry land.
Lake basins can form due to geological processes such as deformation or fracture of stratified rocks or faults, and by natural damming of a river by vegetation, landslide, accumulation ice or the deposit of alluvium or volcanic lava, barrier lakes . Glaciations also created lakes, with glaciers carving out large basins by crushing bedrock and redistributing uprooted material. Other lakes occupy the crater of a dormant or extinct volcano, they are called crater lakes.
The water in a lake comes, on the one hand, from atmospheric precipitation, which feeds it directly, and, on the other hand, from springs, streams and rivers. Lakes form and disappear over geological ages. They can evaporate when the climate becomes drier, or fill with sediment and form a swamp or bog.
In arid regions, where precipitation is negligible and evaporation is intense, the water level of the lakes varies with the seasons and they dry up for long periods.
In endorheic lakes where evaporation is very intense, the mineral substances dissolved in the water are concentrated.
The composition of the dissolved chemical matter brought by the tributary currents depends on the nature of the rocks present in the local drainage network. The main mineral in salt lakes is common salt; in acid lakes, sulphates; in the alkalis, the carbonates; in those of borax, the borates; although many lakes contain combinations of these substances.
Lakes can form at any elevation and are distributed throughout the world, although more than half of them are located in Canada. They are numerous in high latitudes, especially if they are also found in mountainous areas subject to the influence of glaciers. Many lakes are commercially important as a source of minerals or fish, as transportation arteries or as recreational sites. In this same section you can find additional data and information on: The rivers and lakes of the world.
The largest lakes in the world are the Caspian Sea and Lakes Superior and Victoria. The Dead Sea is the lake located at the lowest altitude and 395 meters below sea level. The Caspian Sea, the largest lake in the world consists of salt water and covers an area of 393,897 square kilometers . The deepest freshwater lake is Baikal, with a maximum depth of 1,741 meters.
Wastewater treatment group. Polytechnic University School. University of Seville.
The entry Lake systems was first published in Ambientum Portal Lider Medioambiente.