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92-457: This natural lake provides an environment to preserve rare local water-plant life and seasonal animals. It is owned and managed by the Wildlife Trust of South and West Wales . Surrounded by sheep-grazed common land , it is part of a national nature reserve . Visitors come on foot from the north or on bridleways from the south. Remote and peaceful, Llyn Eiddwen National Nature Reserve lies in

184-737: A greenhouse gas . According to the World Commission on Dams report, where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant. In boreal reservoirs of Canada and Northern Europe, however, greenhouse gas emissions are typically only 2% to 8% of any kind of conventional fossil-fuel thermal generation. A new class of underwater logging operation that targets drowned forests can mitigate

276-463: A low-head hydro power plant with hydrostatic head of few meters to few tens of meters can be classified either as an SHP or an LHP. The other distinction between SHP and LHP is the degree of the water flow regulation: a typical SHP primarily uses the natural water discharge with very little regulation in comparison to an LHP. Therefore, the term SHP is frequently used as a synonym for the run-of-the-river power plant . The largest power producers in

368-409: A body of water from 2 hectares (5 acres) to 8 hectares (20 acres). Pioneering animal ecologist Charles Elton regarded lakes as waterbodies of 40 hectares (99 acres) or more. The term lake is also used to describe a feature such as Lake Eyre , which is a dry basin most of the time but may become filled under seasonal conditions of heavy rainfall. In common usage, many lakes bear names ending with

460-496: A comprehensive analysis of the origin of lakes and proposed what is a widely accepted classification of lakes according to their origin. This classification recognizes 11 major lake types that are divided into 76 subtypes. The 11 major lake types are: Tectonic lakes are lakes formed by the deformation and resulting lateral and vertical movements of the Earth's crust. These movements include faulting, tilting, folding, and warping. Some of

552-421: A flood and fail. Changes in the amount of river flow will correlate with the amount of energy produced by a dam. Lower river flows will reduce the amount of live storage in a reservoir therefore reducing the amount of water that can be used for hydroelectricity. The result of diminished river flow can be power shortages in areas that depend heavily on hydroelectric power. The risk of flow shortage may increase as

644-402: A form of organic lake. They form where a buildup of partly decomposed plant material in a wet environment leaves the vegetated surface below the water table for a sustained period of time. They are often low in nutrients and mildly acidic, with bottom waters low in dissolved oxygen. Artificial lakes or anthropogenic lakes are large waterbodies created by human activity . They can be formed by

736-538: A higher perimeter to area ratio than other lake types. These form where sediment from a tributary blocks the main river. These form where sediment from the main river blocks a tributary, usually in the form of a levee . Lakes formed by other processes responsible for floodplain basin creation. During high floods they are flushed with river water. There are four types: 1. Confluent floodplain lake, 2. Contrafluent-confluent floodplain lake, 3. Contrafluent floodplain lake, 4. Profundal floodplain lake. A solution lake

828-510: A hypolimnion; accordingly, very shallow lakes are excluded from this classification system. Based upon their thermal stratification, lakes are classified as either holomictic , with a uniform temperature and density from top to bottom at a given time of year, or meromictic , with layers of water of different temperature and density that do not intermix. The deepest layer of water in a meromictic lake does not contain any dissolved oxygen so there are no living aerobic organisms . Consequently,

920-538: A key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel -powered energy plants. However, when constructed in lowland rainforest areas, where part of

1012-428: A lake consists of a large area of standing water that occupies an extensive closed depression in limestone, it is also called a karst lake . Smaller solution lakes that consist of a body of standing water in a closed depression within a karst region are known as karst ponds. Limestone caves often contain pools of standing water, which are known as underground lakes . Classic examples of solution lakes are abundant in

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1104-809: A large natural height difference between two waterways, such as a waterfall or mountain lake. A tunnel is constructed to take water from the high reservoir to the generating hall built in a cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway. A simple formula for approximating electric power production at a hydroelectric station is: P = − η   ( m ˙ g   Δ h ) = − η   ( ( ρ V ˙ )   g   Δ h ) {\displaystyle P=-\eta \ ({\dot {m}}g\ \Delta h)=-\eta \ ((\rho {\dot {V}})\ g\ \Delta h)} where Efficiency

1196-470: A large number of studies agree that small ponds are much more abundant than large lakes. For example, one widely cited study estimated that Earth has 304 million lakes and ponds, and that 91% of these are 1 hectare (2.5 acres) or less in area. Despite the overwhelming abundance of ponds, almost all of Earth's lake water is found in fewer than 100 large lakes; this is because lake volume scales superlinearly with lake area. Extraterrestrial lakes exist on

1288-451: A larger amount of methane than those in temperate areas. Like other non-fossil fuel sources, hydropower also has no emissions of sulfur dioxide, nitrogen oxides, or other particulates. Reservoirs created by hydroelectric schemes often provide facilities for water sports , and become tourist attractions themselves. In some countries, aquaculture in reservoirs is common. Multi-use dams installed for irrigation support agriculture with

1380-489: A natural outflow and lose water solely by evaporation or underground seepage, or both. These are termed endorheic lakes. Many lakes are artificial and are constructed for hydroelectric power generation, aesthetic purposes, recreational purposes, industrial use, agricultural use, or domestic water supply . The number of lakes on Earth is undetermined because most lakes and ponds are very small and do not appear on maps or satellite imagery . Despite this uncertainty,

1472-586: A positive risk adjusted return, unless appropriate risk management measures are put in place. While many hydroelectric projects supply public electricity networks, some are created to serve specific industrial enterprises. Dedicated hydroelectric projects are often built to provide the substantial amounts of electricity needed for aluminium electrolytic plants, for example. The Grand Coulee Dam switched to support Alcoa aluminium in Bellingham, Washington , United States for American World War II airplanes before it

1564-545: A relatively constant water supply. Large hydro dams can control floods, which would otherwise affect people living downstream of the project. Managing dams which are also used for other purposes, such as irrigation , is complicated. In 2021 the IEA called for "robust sustainability standards for all hydropower development with streamlined rules and regulations". Large reservoirs associated with traditional hydroelectric power stations result in submersion of extensive areas upstream of

1656-526: A result of climate change . One study from the Colorado River in the United States suggest that modest climate changes, such as an increase in temperature in 2 degree Celsius resulting in a 10% decline in precipitation, might reduce river run-off by up to 40%. Brazil in particular is vulnerable due to its heavy reliance on hydroelectricity, as increasing temperatures, lower water flow and alterations in

1748-403: A result of meandering. The slow-moving river forms a sinuous shape as the outer side of bends are eroded away more rapidly than the inner side. Eventually a horseshoe bend is formed and the river cuts through the narrow neck. This new passage then forms the main passage for the river and the ends of the bend become silted up, thus forming a bow-shaped lake. Their crescent shape gives oxbow lakes

1840-522: A result of the 1959 Hebgen Lake earthquake . Most landslide lakes disappear in the first few months after formation, but a landslide dam can burst suddenly at a later stage and threaten the population downstream when the lake water drains out. In 1911, an earthquake triggered a landslide that blocked a deep valley in the Pamir Mountains region of Tajikistan , forming the Sarez Lake . The Usoi Dam at

1932-448: A small TV/radio). Even smaller turbines of 200–300 W may power a few homes in a developing country with a drop of only 1 m (3 ft). A Pico-hydro setup is typically run-of-the-river , meaning that dams are not used, but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream. An underground power station is generally used at large facilities and makes use of

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2024-455: A source of low-cost renewable energy. Alternatively, small hydro projects may be built in isolated areas that would be uneconomic to serve from a grid, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on

2116-414: A start-up time of the order of a few minutes. Although battery power is quicker its capacity is tiny compared to hydro. It takes less than 10 minutes to bring most hydro units from cold start-up to full load; this is quicker than nuclear and almost all fossil fuel power. Power generation can also be decreased quickly when there is a surplus power generation. Hence the limited capacity of hydropower units

2208-581: A total of 1,500 terawatt-hours (TWh) of electrical energy in one full cycle" which was "about 170 times more energy than the global fleet of pumped storage hydropower plants". Battery storage capacity is not expected to overtake pumped storage during the 2020s. When used as peak power to meet demand, hydroelectricity has a higher value than baseload power and a much higher value compared to intermittent energy sources such as wind and solar. Hydroelectric stations have long economic lives, with some plants still in service after 50–100 years. Operating labor cost

2300-422: A variation in density because of thermal gradients. Stratification can also result from a density variation caused by gradients in salinity. In this case, the hypolimnion and epilimnion are separated not by a thermocline but by a halocline , which is sometimes referred to as a chemocline . Lakes are informally classified and named according to the seasonal variation in their lake level and volume. Some of

2392-448: Is hydroelectric power on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 megawatts (MW) is generally accepted as the upper limit. This may be stretched to 25 MW and 30 MW in Canada and the United States. Small hydro stations may be connected to conventional electrical distribution networks as

2484-443: Is sag ponds . Volcanic lakes are lakes that occupy either local depressions, e.g. craters and maars , or larger basins, e.g. calderas , created by volcanism . Crater lakes are formed in volcanic craters and calderas, which fill up with precipitation more rapidly than they empty via either evaporation, groundwater discharge, or a combination of both. Sometimes the latter are called caldera lakes, although often no distinction

2576-447: Is a stub . You can help Misplaced Pages by expanding it . This article about a Site of Special Scientific Interest is a stub . You can help Misplaced Pages by expanding it . Natural lake A lake is an often naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land . Lakes lie completely on land and are separate from

2668-403: Is a lake occupying a basin formed by surface dissolution of bedrock. In areas underlain by soluble bedrock, its solution by precipitation and percolating water commonly produce cavities. These cavities frequently collapse to form sinkholes that form part of the local karst topography . Where groundwater lies near the grounds surface, a sinkhole will be filled water as a solution lake. If such

2760-627: Is also usually low, as plants are automated and have few personnel on site during normal operation. Where a dam serves multiple purposes, a hydroelectric station may be added with relatively low construction cost, providing a useful revenue stream to offset the costs of dam operation. It has been calculated that the sale of electricity from the Three Gorges Dam will cover the construction costs after 5 to 8 years of full generation. However, some data shows that in most countries large hydropower dams will be too costly and take too long to build to deliver

2852-462: Is dammed behind an ice shelf that is attached to the coastline. They are mostly found in Antarctica. Fluvial (or riverine) lakes are lakes produced by running water. These lakes include plunge pool lakes , fluviatile dams and meander lakes. The most common type of fluvial lake is a crescent-shaped lake called an oxbow lake due to the distinctive curved shape. They can form in river valleys as

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2944-466: Is highest in the winter when solar energy is at a minimum. Pico hydro is hydroelectric power generation of under 5 kW . It is useful in small, remote communities that require only a small amount of electricity. For example, the 1.1 kW Intermediate Technology Development Group Pico Hydro Project in Kenya supplies 57 homes with very small electric loads (e.g., a couple of lights and a phone charger, or

3036-445: Is initially produced during construction of the project, and some methane is given off annually by reservoirs, hydro has one of the lowest lifecycle greenhouse gas emissions for electricity generation. The low greenhouse gas impact of hydroelectricity is found especially in temperate climates . Greater greenhouse gas emission impacts are found in the tropical regions because the reservoirs of power stations in tropical regions produce

3128-448: Is made. An example is Crater Lake in Oregon , in the caldera of Mount Mazama . The caldera was created in a massive volcanic eruption that led to the subsidence of Mount Mazama around 4860 BCE. Other volcanic lakes are created when either rivers or streams are dammed by lava flows or volcanic lahars . The basin which is now Malheur Lake , Oregon was created when a lava flow dammed

3220-462: Is not an energy source, and appears as a negative number in listings. Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that only the water coming from upstream is available for generation at that moment, and any oversupply must pass unused. A constant supply of water from a lake or existing reservoir upstream is a significant advantage in choosing sites for run-of-the-river. A tidal power station makes use of

3312-452: Is not generally used to produce base power except for vacating the flood pool or meeting downstream needs. Instead, it can serve as backup for non-hydro generators. The major advantage of conventional hydroelectric dams with reservoirs is their ability to store water at low cost for dispatch later as high value clean electricity. In 2021, the IEA estimated that the "reservoirs of all existing conventional hydropower plants combined can store

3404-410: Is often higher (that is, closer to 1) with larger and more modern turbines. Annual electric energy production depends on the available water supply. In some installations, the water flow rate can vary by a factor of 10:1 over the course of a year. Hydropower is a flexible source of electricity since stations can be ramped up and down very quickly to adapt to changing energy demands. Hydro turbines have

3496-429: Is unknown but is estimated to be at least 2 million. Finland has 168,000 lakes of 500 square metres (5,400 sq ft) in area, or larger, of which 57,000 are large (10,000 square metres (110,000 sq ft) or larger). Most lakes have at least one natural outflow in the form of a river or stream , which maintain a lake's average level by allowing the drainage of excess water. Some lakes do not have

3588-657: The Bonneville Dam in 1937 and being recognized by the Flood Control Act of 1936 as the premier federal flood control agency. Hydroelectric power stations continued to become larger throughout the 20th century. Hydropower was referred to as "white coal". Hoover Dam 's initial 1,345 MW power station was the world's largest hydroelectric power station in 1936; it was eclipsed by the 6,809 MW Grand Coulee Dam in 1942. The Itaipu Dam opened in 1984 in South America as

3680-533: The Industrial Revolution would drive development as well. In 1878, the world's first hydroelectric power scheme was developed at Cragside in Northumberland , England, by William Armstrong . It was used to power a single arc lamp in his art gallery. The old Schoelkopf Power Station No. 1 , US, near Niagara Falls , began to produce electricity in 1881. The first Edison hydroelectric power station,

3772-778: The International Exhibition of Hydropower and Tourism , with over one million visitors 1925. By 1920, when 40% of the power produced in the United States was hydroelectric, the Federal Power Act was enacted into law. The Act created the Federal Power Commission to regulate hydroelectric power stations on federal land and water. As the power stations became larger, their associated dams developed additional purposes, including flood control , irrigation and navigation . Federal funding became necessary for large-scale development, and federally owned corporations, such as

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3864-752: The Malheur River . Among all lake types, volcanic crater lakes most closely approximate a circular shape. Glacial lakes are lakes created by the direct action of glaciers and continental ice sheets. A wide variety of glacial processes create enclosed basins. As a result, there are a wide variety of different types of glacial lakes and it is often difficult to define clear-cut distinctions between different types of glacial lakes and lakes influenced by other activities. The general types of glacial lakes that have been recognized are lakes in direct contact with ice, glacially carved rock basins and depressions, morainic and outwash lakes, and glacial drift basins. Glacial lakes are

3956-540: The Proto-Indo-European root * leǵ- ('to leak, drain'). Cognates include Dutch laak ('lake, pond, ditch'), Middle Low German lāke ('water pooled in a riverbed, puddle') as in: de:Wolfslake , de:Butterlake , German Lache ('pool, puddle'), and Icelandic lækur ('slow flowing stream'). Also related are the English words leak and leach . There is considerable uncertainty about defining

4048-605: The Tennessee Valley Authority (1933) and the Bonneville Power Administration (1937) were created. Additionally, the Bureau of Reclamation which had begun a series of western US irrigation projects in the early 20th century, was now constructing large hydroelectric projects such as the 1928 Hoover Dam . The United States Army Corps of Engineers was also involved in hydroelectric development, completing

4140-569: The Vulcan Street Plant , began operating September 30, 1882, in Appleton, Wisconsin , with an output of about 12.5 kilowatts. By 1886 there were 45 hydroelectric power stations in the United States and Canada; and by 1889 there were 200 in the United States alone. At the beginning of the 20th century, many small hydroelectric power stations were being constructed by commercial companies in mountains near metropolitan areas. Grenoble , France held

4232-399: The density of water varies with temperature, with a maximum at +4 degrees Celsius, thermal stratification is an important physical characteristic of a lake that controls the fauna and flora , sedimentation, chemistry, and other aspects of individual lakes. First, the colder, denser water typically forms a layer near the bottom, which is called the hypolimnion . Second, normally overlying

4324-605: The ocean , although they may be connected with the ocean by rivers . Lakes, as with other bodies of water , are part of the water cycle , the processes by which water moves around the Earth. Most lakes are freshwater and account for almost all the world's surface freshwater, but some are salt lakes with salinities even higher than that of seawater . Lakes vary significantly in surface area and volume of water. Lakes are typically larger and deeper than ponds , which are also water-filled basins on land, although there are no official definitions or scientific criteria distinguishing

4416-506: The potential energy of dammed water driving a water turbine and generator . The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head . A large pipe (the " penstock ") delivers water from the reservoir to the turbine. This method produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand,

4508-400: The water frame , and continuous production played a significant part in the development of the factory system, with modern employment practices. In the 1840s, hydraulic power networks were developed to generate and transmit hydro power to end users. By the late 19th century, the electrical generator was developed and could now be coupled with hydraulics. The growing demand arising from

4600-583: The Earth by extraterrestrial objects (either meteorites or asteroids ). Examples of meteorite lakes are Lonar Lake in India, Lake El'gygytgyn in northeast Siberia, and the Pingualuit crater lake in Quebec, Canada. As in the cases of El'gygytgyn and Pingualuit, meteorite lakes can contain unique and scientifically valuable sedimentary deposits associated with long records of paleoclimatic changes. In addition to

4692-463: The IEA released a main-case forecast of 141 GW generated by hydropower over 2022–2027, which is slightly lower than deployment achieved from 2017–2022. Because environmental permitting and construction times are long, they estimate hydropower potential will remain limited, with only an additional 40 GW deemed possible in the accelerated case. In 2021 the IEA said that major modernisation refurbishments are required. Most hydroelectric power comes from

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4784-551: The Lusatian Lake District, Germany. In India, Sudarshana Lake is a historical artificial lake located in the semi-arid region of Girnar, Gujarat, originally constructed during the reign of Chandragupta Maurya. See: List of notable artificial lakes in the United States Meteorite lakes, also known as crater lakes (not to be confused with volcanic crater lakes ), are created by catastrophic impacts with

4876-464: The ability to transport particles heavier than itself downstream. This has a negative effect on dams and subsequently their power stations, particularly those on rivers or within catchment areas with high siltation. Siltation can fill a reservoir and reduce its capacity to control floods along with causing additional horizontal pressure on the upstream portion of the dam. Eventually, some reservoirs can become full of sediment and useless or over-top during

4968-595: The balance between stream flow and power production. Micro hydro means hydroelectric power installations that typically produce up to 100 kW of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel. Micro hydro systems complement photovoltaic solar energy systems because in many areas water flow, and thus available hydro power,

5060-856: The base of the valley has remained in place for more than 100 years but the terrain below the lake is in danger of a catastrophic flood if the dam were to fail during a future earthquake. Tal-y-llyn Lake in north Wales is a landslide lake dating back to the last glaciation in Wales some 20000 years ago. Aeolian lakes are produced by wind action . These lakes are found mainly in arid environments, although some aeolian lakes are relict landforms indicative of arid paleoclimates . Aeolian lakes consist of lake basins dammed by wind-blown sand; interdunal lakes that lie between well-oriented sand dunes ; and deflation basins formed by wind action under previously arid paleoenvironments. Moses Lake in Washington , United States,

5152-915: The courses of mature rivers, where a river channel has widened over a basin formed by eroded floodplains and wetlands . Some lakes are found in caverns underground . Some parts of the world have many lakes formed by the chaotic drainage patterns left over from the last ice age . All lakes are temporary over long periods of time , as they will slowly fill in with sediments or spill out of the basin containing them. Artificially controlled lakes are known as reservoirs , and are usually constructed for industrial or agricultural use, for hydroelectric power generation, for supplying domestic drinking water , for ecological or recreational purposes, or for other human activities. The word lake comes from Middle English lake ('lake, pond, waterway'), from Old English lacu ('pond, pool, stream'), from Proto-Germanic * lakō ('pond, ditch, slow moving stream'), from

5244-513: The creation of lakes by the disruption of preexisting drainage networks, it also creates within arid regions endorheic basins that contain salt lakes (also called saline lakes). They form where there is no natural outlet, a high evaporation rate and the drainage surface of the water table has a higher-than-normal salt content. Examples of these salt lakes include Great Salt Lake and the Dead Sea . Another type of tectonic lake caused by faulting

5336-404: The daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot water wheels . Tidal power is viable in a relatively small number of locations around

5428-505: The dams, sometimes destroying biologically rich and productive lowland and riverine valley forests, marshland and grasslands. Damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife. The loss of land is often exacerbated by habitat fragmentation of surrounding areas caused by the reservoir. Hydroelectric projects can be disruptive to surrounding aquatic ecosystems both upstream and downstream of

5520-622: The difference between lakes and ponds , and neither term has an internationally accepted definition across scientific disciplines or political boundaries. For example, limnologists have defined lakes as water bodies that are simply a larger version of a pond, which can have wave action on the shoreline or where wind-induced turbulence plays a major role in mixing the water column. None of these definitions completely excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are increasingly used to separate ponds and lakes. Definitions for lake range in minimum sizes for

5612-690: The effect of forest decay. Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned. In 2000, the World Commission on Dams estimated that dams had physically displaced 40–80 million people worldwide. Because large conventional dammed-hydro facilities hold back large volumes of water, a failure due to poor construction, natural disasters or sabotage can be catastrophic to downriver settlements and infrastructure. During Typhoon Nina in 1975 Banqiao Dam in Southern China failed when more than

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5704-523: The exception of criterion 3, the others have been accepted or elaborated upon by other hydrology publications. The majority of lakes on Earth are freshwater , and most lie in the Northern Hemisphere at higher latitudes . Canada , with a deranged drainage system , has an estimated 31,752 lakes larger than 3 square kilometres (1.2 sq mi) in surface area. The total number of lakes in Canada

5796-399: The excess generation capacity is used to pump water into the higher reservoir, thus providing demand side response . When the demand becomes greater, water is released back into the lower reservoir through a turbine. In 2021 pumped-storage schemes provided almost 85% of the world's 190 GW of grid energy storage and improve the daily capacity factor of the generation system. Pumped storage

5888-534: The forest is inundated, substantial amounts of greenhouse gases may be emitted. Construction of a hydroelectric complex can have significant environmental impact, principally in loss of arable land and population displacement. They also disrupt the natural ecology of the river involved, affecting habitats and ecosystems, and siltation and erosion patterns. While dams can ameliorate the risks of flooding, dam failure can be catastrophic. In 2021, global installed hydropower electrical capacity reached almost 1,400 GW,

5980-582: The gentle slopes of Mynydd Bach , to the north west of Tregaron town in Ceredigion. The wet and quiet nature of its habitats suits shy creatures such as water voles and otters. A climb to the summit of the surrounding hills reveals views of Cardigan Bay to the west, and of the Pumlumon and Elenydd uplands to the north and east. 52°16′59″N 4°02′38″W  /  52.283°N 4.044°W  / 52.283; -4.044 This Ceredigion location article

6072-506: The highest among all renewable energy technologies. Hydroelectricity plays a leading role in countries like Brazil, Norway and China. but there are geographical limits and environmental issues. Tidal power can be used in coastal regions. China added 24 GW in 2022, accounting for nearly three-quarters of global hydropower capacity additions. Europe added 2 GW, the largest amount for the region since 1990. Meanwhile, globally, hydropower generation increased by 70 TWh (up 2%) in 2022 and remains

6164-422: The hypolimnion is a transition zone known as the metalimnion . Finally, overlying the metalimnion is a surface layer of warmer water with a lower density, called the epilimnion . This typical stratification sequence can vary widely, depending on the specific lake or the time of year, or a combination of both. The classification of lakes by thermal stratification presupposes lakes with sufficient depth to form

6256-907: The intentional damming of rivers and streams, rerouting of water to inundate a previously dry basin , or the deliberate filling of abandoned excavation pits by either precipitation runoff , ground water , or a combination of both. Artificial lakes may be used as storage reservoirs that provide drinking water for nearby settlements , to generate hydroelectricity , for flood management , for supplying agriculture or aquaculture , or to provide an aquatic sanctuary for parks and nature reserves . The Upper Silesian region of southern Poland contains an anthropogenic lake district consisting of more than 4,000 water bodies created by human activity. The diverse origins of these lakes include: reservoirs retained by dams, flooded mines, water bodies formed in subsidence basins and hollows, levee ponds, and residual water bodies following river regulation. Same for

6348-466: The karst regions at the Dalmatian coast of Croatia and within large parts of Florida . A landslide lake is created by the blockage of a river valley by either mudflows , rockslides , or screes . Such lakes are most common in mountainous regions. Although landslide lakes may be large and quite deep, they are typically short-lived. An example of a landslide lake is Quake Lake , which formed as

6440-420: The lake level. Hydro-electric power Hydroelectricity , or hydroelectric power , is electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity , almost 4,210 TWh in 2023, which is more than all other renewable sources combined and also more than nuclear power . Hydropower can provide large amounts of low-carbon electricity on demand, making it

6532-648: The largest lakes on Earth are rift lakes occupying rift valleys, e.g. Central African Rift lakes and Lake Baikal . Other well-known tectonic lakes, Caspian Sea , the Sea of Aral , and other lakes from the Pontocaspian occupy basins that have been separated from the sea by the tectonic uplift of the sea floor above the ocean level. Often, the tectonic action of crustal extension has created an alternating series of parallel grabens and horsts that form elongate basins alternating with mountain ranges. Not only does this promote

6624-519: The largest renewable energy source, surpassing all other technologies combined. Hydropower has been used since ancient times to grind flour and perform other tasks. In the late 18th century hydraulic power provided the energy source needed for the start of the Industrial Revolution . In the mid-1700s, French engineer Bernard Forest de Bélidor published Architecture Hydraulique , which described vertical- and horizontal-axis hydraulic machines, and in 1771 Richard Arkwright 's combination of water power ,

6716-731: The largest, producing 14 GW , but was surpassed in 2008 by the Three Gorges Dam in China at 22.5 GW . Hydroelectricity would eventually supply some countries, including Norway , Democratic Republic of the Congo , Paraguay and Brazil , with over 85% of their electricity. In 2021 the International Energy Agency (IEA) said that more efforts are needed to help limit climate change . Some countries have highly developed their hydropower potential and have very little room for growth: Switzerland produces 88% of its potential and Mexico 80%. In 2022,

6808-528: The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed, which allows for the development of lacustrine deposits . In a holomictic lake, the uniformity of temperature and density allows the lake waters to completely mix. Based upon thermal stratification and frequency of turnover, holomictic lakes are divided into amictic lakes , cold monomictic lakes , dimictic lakes , warm monomictic lakes, polymictic lakes , and oligomictic lakes. Lake stratification does not always result from

6900-560: The level of a lake are controlled by the difference between the input and output compared to the total volume of the lake. Significant input sources are precipitation onto the lake, runoff carried by streams and channels from the lake's catchment area, groundwater channels and aquifers, and artificial sources from outside the catchment area. Output sources are evaporation from the lake, surface and groundwater flows, and any extraction of lake water by humans. As climate conditions and human water requirements vary, these will create fluctuations in

6992-481: The mainland; lakes cut off from larger lakes by a bar; or lakes divided by the meeting of two spits. Organic lakes are lakes created by the actions of plants and animals. On the whole they are relatively rare in occurrence and quite small in size. In addition, they typically have ephemeral features relative to the other types of lakes. The basins in which organic lakes occur are associated with beaver dams, coral lakes, or dams formed by vegetation. Peat lakes are

7084-424: The mode of origin, lakes have been named and classified according to various other important factors such as thermal stratification , oxygen saturation, seasonal variations in lake volume and water level, salinity of the water mass, relative seasonal permanence, degree of outflow, and so on. The names used by the lay public and in the scientific community for different types of lakes are often informally derived from

7176-485: The moon Titan , which orbits the planet Saturn . The shape of lakes on Titan is very similar to those on Earth. Lakes were formerly present on the surface of Mars, but are now dry lake beds . In 1957, G. Evelyn Hutchinson published a monograph titled A Treatise on Limnology , which is regarded as a landmark discussion and classification of all major lake types, their origin, morphometric characteristics, and distribution. Hutchinson presented in his publication

7268-415: The morphology of the lakes' physical characteristics or other factors. Also, different cultures and regions of the world have their own popular nomenclature. One important method of lake classification is on the basis of thermal stratification, which has a major influence on the animal and plant life inhabiting a lake, and the fate and distribution of dissolved and suspended material in the lake. For example,

7360-406: The most numerous lakes in the world. Most lakes in northern Europe and North America have been either influenced or created by the latest, but not last, glaciation, to have covered the region. Glacial lakes include proglacial lakes , subglacial lakes , finger lakes , and epishelf lakes. Epishelf lakes are highly stratified lakes in which a layer of freshwater, derived from ice and snow melt,

7452-791: The names include: Lakes may be informally classified and named according to the general chemistry of their water mass. Using this classification method, the lake types include: A paleolake (also palaeolake ) is a lake that existed in the past when hydrological conditions were different. Quaternary paleolakes can often be identified on the basis of relict lacustrine landforms, such as relict lake plains and coastal landforms that form recognizable relict shorelines called paleoshorelines . Paleolakes can also be recognized by characteristic sedimentary deposits that accumulated in them and any fossils that might be contained in these sediments. The paleoshorelines and sedimentary deposits of paleolakes provide evidence for prehistoric hydrological changes during

7544-562: The organic-rich deposits of pre-Quaternary paleolakes are important either for the thick deposits of oil shale and shale gas contained in them, or as source rocks of petroleum and natural gas . Although of significantly less economic importance, strata deposited along the shore of paleolakes sometimes contain coal seams . Lakes have numerous features in addition to lake type, such as drainage basin (also known as catchment area), inflow and outflow, nutrient content, dissolved oxygen , pollutants , pH , and sedimentation . Changes in

7636-633: The plant site. Generation of hydroelectric power changes the downstream river environment. Water exiting a turbine usually contains very little suspended sediment, which can lead to scouring of river beds and loss of riverbanks. The turbines also will kill large portions of the fauna passing through, for instance 70% of the eel passing a turbine will perish immediately. Since turbine gates are often opened intermittently, rapid or even daily fluctuations in river flow are observed. Drought and seasonal changes in rainfall can severely limit hydropower. Water may also be lost by evaporation. When water flows it has

7728-450: The rainfall regime, could reduce total energy production by 7% annually by the end of the century. Lower positive impacts are found in the tropical regions. In lowland rainforest areas, where inundation of a part of the forest is necessary, it has been noted that the reservoirs of power plants produce substantial amounts of methane . This is due to plant material in flooded areas decaying in an anaerobic environment and forming methane,

7820-404: The thermal stratification, as well as the degree and frequency of mixing, has a strong control over the distribution of oxygen within the lake. Professor F.-A. Forel , also referred to as the "Father of limnology", was the first scientist to classify lakes according to their thermal stratification. His system of classification was later modified and improved upon by Hutchinson and Löffler. As

7912-456: The times that they existed. There are two types of paleolake: Paleolakes are of scientific and economic importance. For example, Quaternary paleolakes in semidesert basins are important for two reasons: they played an extremely significant, if transient, role in shaping the floors and piedmonts of many basins; and their sediments contain enormous quantities of geologic and paleontologic information concerning past environments. In addition,

8004-641: The two. Lakes are also distinct from lagoons , which are generally shallow tidal pools dammed by sandbars or other material at coastal regions of oceans or large lakes. Most lakes are fed by springs , and both fed and drained by creeks and rivers , but some lakes are endorheic without any outflow, while volcanic lakes are filled directly by precipitation runoffs and do not have any inflow streams. Natural lakes are generally found in mountainous areas (i.e. alpine lakes ), dormant volcanic craters , rift zones and areas with ongoing glaciation . Other lakes are found in depressed landforms or along

8096-462: The word pond , and a lesser number of names ending with lake are, in quasi-technical fact, ponds. One textbook illustrates this point with the following: "In Newfoundland, for example, almost every lake is called a pond, whereas in Wisconsin, almost every pond is called a lake." One hydrology book proposes to define the term "lake" as a body of water with the following five characteristics: With

8188-524: The world are hydroelectric power stations, with some hydroelectric facilities capable of generating more than double the installed capacities of the current largest nuclear power stations . Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred megawatts are generally considered large hydroelectric facilities. Currently, only seven facilities over 10 GW ( 10,000 MW ) are in operation worldwide, see table below. Small hydro

8280-539: The world. The classification of hydropower plants starts with two top-level categories: The classification of a plant as an SHP or LHP is primarily based on its nameplate capacity , the threshold varies by the country, but in any case a plant with the capacity of 50 MW or more is considered an LHP. As an example, for China, SHP power is below 25 MW, for India - below 15 MW, most of Europe - below 10 MW. The SHP and LHP categories are further subdivided into many subcategories that are not mutually exclusive. For example,

8372-573: Was allowed to provide irrigation and power to citizens (in addition to aluminium power) after the war. In Suriname , the Brokopondo Reservoir was constructed to provide electricity for the Alcoa aluminium industry. New Zealand 's Manapouri Power Station was constructed to supply electricity to the aluminium smelter at Tiwai Point . Since hydroelectric dams do not use fuel, power generation does not produce carbon dioxide . While carbon dioxide

8464-611: Was originally a shallow natural lake and an example of a lake basin dammed by wind-blown sand. China's Badain Jaran Desert is a unique landscape of megadunes and elongated interdunal aeolian lakes, particularly concentrated in the southeastern margin of the desert. Shoreline lakes are generally lakes created by blockage of estuaries or by the uneven accretion of beach ridges by longshore and other currents. They include maritime coastal lakes, ordinarily in drowned estuaries; lakes enclosed by two tombolos or spits connecting an island to

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