A lake is a body of relatively still water of considerable size, localized in a basin, that is surrounded by land apart from a river, stream, or other form of moving water that serves to feed or drain the lake. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds.Lakes can be contrasted with rivers or streams, which are usually flowing. However most lakes are fed and drained by rivers and streams.
Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.
Many lakes are artificial and are constructed for industrial or agricultural use, for hydro-electric power generation or domestic water supply, or for aesthetic or recreational purposes.
Water can enter lakes from a variety of sources including groundwater, runoff from the watershed, surface waters (like streams and rivers) flowing into the lake, and direct precipitation into the lake. Water leaves lakes through groundwater or surface water flow and evaporation.
Lakes can be classified into five main lake types based on how water enters and exits the lake. For some lakes, all or most of their water enters the lake through one source (such as groundwater), other lakes may receive water through several sources. The water quality of a lake and species of fish present are significantly influenced by the lake type.
These lakes do not have an inlet or an outlet, and only occasionally overflow. As landlocked water bodies, the principal source of water is precipitation or runoff, supplemented by groundwater from the immediate drainage area. Since seepage lakes commonly reflect groundwater levels and rainfall patterns, water levels may fluctuate seasonally. Seepage lakes are the most common lake type in Wisconsin.
Seepage lakes frequently have a less diverse fishery because they are not influenced by streams. Seepage lakes also have a smaller drainage area, which may help to account for lower nutrient levels
These lakes have no inlet, but do have an outlet. The primary source of water for spring lakes is groundwater flowing into the bottom of the lake from inside and outside the immediate surface drainage area. Spring lakes are the headwaters of many streams and are a fairly common type of lake in northern Wisconsin.
Groundwater drained lakes
These lakes have no inlet, but like spring lakes, have a continuously flowing outlet. Drained lakes are not groundwater-fed. Their primary source of water is from precipitation and direct drainage from the surrounding land.
Frequently, the water levels in drained lakes will fluctuate depending on the supply of water. Under severe conditions, the outlets from drained lakes may become intermittent. Drained lakes are the least common lake type found in Wisconsin.
These lakes have both an inlet and outlet where the main water source is stream drainage. Most major rivers in Wisconsin have drainage lakes along their course. Drainage lakes support fish populations which are not necessarily identical to the streams connected to them. Drainage lakes usually have higher nutrient levels than many natural seepage or spring lakes.
Artificial lakes are human-made bodies of water referred to as impoundments. A lake is considered an impoundment if one-half or more of its maximum depth results from a dam or other type of control structure. An impoundment is considered a drainage lake since it has an inlet and outlet with its principal water source coming from stream drainage.
Impoundments may support fish populations which are not necessarily identical to the streams connected to them. Impoundments usually have higher nutrient levels than many natural seepage or spring lakes.
Periglacial lake: Part of the lake’s margin is formed by an ice sheet, ice cap or glacier, the ice having obstructed the natural drainage of the land.
Subglacial lake: A lake which is permanently covered by ice. They can occur under glaciers, ice caps or ice sheets. There are many such lakes, but Lake Vostok in Antarctica is by far the largest. They are kept liquid because the overlying ice acts as a thermal insulator retaining energy introduced to its underside by friction, by water percolating through crevasses, by the pressure from the mass of the ice sheet above or by geothermal heating below.
Glacial lake: a lake with origins in a melted glacier, such as a kettle lake.
Artificial lake: A lake created by flooding land behind a dam, called an impoundment or reservoir, by deliberate human excavation, or by the flooding of an excavation incident to a mineral-extraction operation such as an open pit mine or quarry. Some of the world’s largest lakes are reservoirs like Hirakud Dam in India.
Endorheic lake, terminal or closed: A lake which has no significant outflow, either through rivers or underground diffusion. Any water within an endorheic basin leaves the system only through evaporation or seepage. These lakes, such as Lake Eyre in central Australia or the Aral Sea in central Asia, are most common in desert locations.
Meromictic lake: A lake which has layers of water which do not intermix. The deepest layer of water in such a lake does not contain any dissolved oxygen. The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed because there are no living aerobic organisms.
Fjord lake: A lake in a glacially eroded valley that has been eroded below sea level.
Oxbow lake: A lake which is formed when a wide meander from a stream or a river is cut off to form a lake. They are called “oxbow” lakes due to the distinctive curved shape that results from this process.
Rift lake or sag pond: A lake which forms as a result of subsidence along a geological fault in the Earth’s tectonic plates. Examples include the Rift Valley lakes of eastern Africa and Lake Baikal in Siberia.
Underground lake: A lake which is formed under the surface of the Earth’s crust. Such a lake may be associated with caves, aquifers or springs.
Crater lake: A lake which forms in a volcanic caldera or crater after the volcano has been inactive for some time. Water in this type of lake may be fresh or highly acidic, and may contain various dissolved minerals. Some also have geothermal activity, especially if the volcano is merely dormant rather than extinct.
Lava lake: A pool of molten lava contained in a volcanic crater or other depression. Lava lakes that have partly or completely solidified are also referred to as lava lakes.
Former: A lake which is no longer in existence. Such lakes include prehistoric lakes and lakes which have permanently dried up through evaporation or human intervention. Owens Lake in California, USA, is an example of a former lake. Former lakes are a common feature of the Basin and Range area of southwestern North America.
Ephemeral lake, intermittent lake, or seasonal lake: A seasonal lake that exists as a body of water during only part of the year.
Shrunken: Closely related to former lakes, a shrunken lake is one which has drastically decreased in size over geological time. Lake Agassiz, which once covered much of central North America, is a good example of a shrunken lake. Two notable remnants of this lake are Lake Winnipeg and Lake Winnipegosis.
Eolic lake: A lake which forms in a depression created by the activity of the winds.
Vlei, in South Africa, shallow lakes which vary considerably with seasons.
Epishelf lakes, unique lakes which exist on top of a dense saltwater body and are surrounded by ice. These are mostly found in the Antarctica.
Link(s),Source(s) and Inspiration(s):
- The Incredible Bubble Lake: Lake Abraham (neatorama.com)
- Great Lakes Reach Record Low Water Levels (sott.net)
- Lake Winnipeg up for ‘threatened lake of the year’ (metronews.ca)
- Record Low Water Levels in Lake Huron, Lake Michigan (commondreams.org)