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A waterfall is a point in a
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...
or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or
ice shelf An ice shelf is a large floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Greenland, Northern Canada, and the Russian Arctic. The ...
. Waterfalls can be formed in several ways, but the most common method of formation is that a river courses over a top layer of resistant bedrock before falling on to softer rock, which erodes faster, leading to an increasingly high fall. Waterfalls have been studied for their impact on species living in and around them. Humans have had a distinct relationship with waterfalls for years, travelling to see them, exploring and naming them. They can present formidable barriers to navigation along rivers. Waterfalls are religious sites in many cultures. Since the 18th century they have received increased attention as tourist destinations, sources of
hydropower Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting the gravitational potential or kinetic energy of a w ...
, andparticularly since the mid-20th centuryas subjects of research.


Definition and terminology

A waterfall is generally defined as a point in a river where water flows over a steep drop that is close to or directly vertical. In 2000 Mabin specified that "The horizontal distance between the positions of the lip and
plunge pool A plunge pool (or plunge basin or waterfall lake) is a deep depression in a stream bed at the base of a waterfall or shut-in. It is created by the erosional forces of cascading water on the rocks at formation's base where the water impacts.Mars ...
should be no more than c 25% of the waterfall height." There are various types and methods to classify waterfalls. Some scholars have included rapids as a subsection. What actually constitutes a waterfall continues to be debated. Waterfalls are sometimes interchangeably referred to as "cascades" and "cataracts", though some sources specify a cataract as being a larger and more powerful waterfall and a cascade as being smaller. A plunge pool is a type of
stream pool A stream pool, in hydrology, is a stretch of a river or stream in which the water depth is above average and the water velocity is below average. Formation A stream pool may be bedded with sediment or armoured with gravel, and in some cases t ...
formed at the bottom of a waterfall.


Formation

Waterfalls are commonly formed in the upper course of a river where lakes flow into valleys in steep mountains. A river sometimes flows over a large step in the rocks that may have been formed by a
fault line In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
. Waterfalls can occur along the edge of a glacial trough, where a stream or river flowing into a
glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...
continues to flow into a valley after the glacier has receded or melted. The large waterfalls in
Yosemite Valley Yosemite Valley ( ; ''Yosemite'', Miwok for "killer") is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of Central California. The valley is about long and deep, surrounded by high granite summits such as Hal ...
are examples of this phenomenon, which is referred to as a
hanging valley A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...
. Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other. When warm and cold water meet by a gorge in the ocean, large underwater waterfalls can form as the cold water rushes to the bottom.


Caprock model

The caprock model of waterfall formation states that the river courses over resistant bedrock, erosion happens slowly and is dominated by impacts of water-borne sediment on the rock, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it may pluck material from the riverbed, if the bed is fractured or otherwise more erodible. Hydraulic jets and hydraulic jumps at the toe of a falls can generate large forces to erode the bed, especially when forces are amplified by water-borne sediment. Horseshoe-shaped falls focus the erosion to a central point, also enhancing riverbed change below a waterfalls. A process known as "potholing" involves local erosion of a potentially deep hole in bedrock due to turbulent
whirlpool A whirlpool is a body of rotating water produced by opposing currents or a current running into an obstacle. Small whirlpools form when a bath or a sink is draining. More powerful ones formed in seas or oceans may be called maelstroms ( ). ''Vo ...
s spinning stones around on the bed, drilling it out. Sand and stones carried by the watercourse therefore increase erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one-and-a-half metres per year. Often, the rock stratum just below the more resistant shelf will be of a softer type, meaning that undercutting due to splashback will occur here to form a shallow cave-like formation known as a rock shelter under and behind the waterfall. Eventually, the
outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...
ping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by
attrition Attrition may refer to *Attrition warfare, the military strategy of wearing down the enemy by continual losses in personnel and material **War of Attrition, fought between Egypt and Israel from 1968 to 1970 **War of attrition (game), a model of agg ...
as they collide with each other, and they also erode the base of the waterfall by abrasion, creating a deep
plunge pool A plunge pool (or plunge basin or waterfall lake) is a deep depression in a stream bed at the base of a waterfall or shut-in. It is created by the erosional forces of cascading water on the rocks at formation's base where the water impacts.Mars ...
in the gorge downstream. Streams can become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the
kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acc ...
of the water hitting the bottom. However, a study of waterfalls systematics reported that waterfalls can be wider or narrower above or below a falls, so almost anything is possible given the right geological and hydrological setting. Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by
earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...
s or landslides or
volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...
es can lead to the formation of waterfalls.


Ecology

Waterfalls are an important factor in determining the distribution of lotic organisms such as fish and aquatic invertebrates, as they may restrict dispersal along streams. The presence or absence of certain species can have cascading ecological effects, and thus cause differences in trophic regimes above and below waterfalls. Certain aquatic insects also specialize in the environment of the waterfall itself. A 2012 study of the Agbokim Waterfalls, has suggested that they hold biodiversity to a much higher extent than previously thought. Waterfalls also affect terrestrial species. They create a small microclimate in their immediate vicinity characterized by cooler temperatures and higher humidity than the surrounding region, which may support diverse communities of mosses and liverworts. Species of these plants may have disjunct populations at waterfall zones far from their core range. Waterfalls provide nesting cover for several species of bird, such as the black swift and
white-throated dipper The white-throated dipper (''Cinclus cinclus''), also known as the European dipper or just dipper, is an aquatic passerine bird found in Europe, Middle East, Central Asia and the Indian Subcontinent. The species is divided into several subspec ...
. These species preferentially nest in the space behind the falling water, which is thought to be a strategy to avoid predation.


Types

Some waterfalls are also distinct in that they do not flow continuously. Ephemeral waterfalls only flow after a rain or a significant snowmelt. Waterfalls can also be found
underground Underground most commonly refers to: * Subterranea (geography), the regions beneath the surface of the Earth Underground may also refer to: Places * The Underground (Boston), a music club in the Allston neighborhood of Boston * The Underground ...
and in oceans.


Humans and waterfalls


Research

The geographer Andrew Goudie wrote in 2020 that waterfalls have received "surprisingly limited research."
Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister, ...
wrote about them in the 1820s. There is no name for the specific field of researching waterfalls, and in the published literature been described as "scattered", though it is popular to describe studying waterfalls as "waterfallology". An early paper written on waterfalls was published in 1884 by
William Morris Davis William Morris Davis (February 12, 1850 – February 5, 1934) was an American geographer, geologist, geomorphologist, and meteorologist, often called the "father of American geography". He was born into a prominent Quaker family in Philadelphia, ...
, a geologist known as the "father of American geography". In the 1930s Edward Rashleigh published a pioneering work on waterfalls. In 1942 Oscar von Engeln wrote of the lack of research on waterfalls: As late as 1985 a scholar felt that "waterfalls remain a very much neglected aspect of river studies". Studies of waterfalls increased dramatically in the second half of the 20th century. Numerous waterfall guidebooks exist, and the World Waterfall Database is a website cataloging thousands of waterfalls.


Exploration and naming

Many explorers have visited waterfalls. European explorers recorded waterfalls they came across. In 1493,
Christopher Columbus Christopher Columbus * lij, Cristoffa C(or)ombo * es, link=no, Cristóbal Colón * pt, Cristóvão Colombo * ca, Cristòfor (or ) * la, Christophorus Columbus. (; born between 25 August and 31 October 1451, died 20 May 1506) was a ...
noted Carbet Falls in Guadeloupe, which was likely the first waterfall Europeans recorded seeing in the Americas. In the late 1600s,
Louis Hennepin Father Louis Hennepin, O.F.M. baptized Antoine, (; 12 May 1626 – 5 December 1704) was a Belgian Roman Catholic priest and missionary of the Franciscan Recollet order (French: ''Récollets'') and an explorer of the interior of North Amer ...
visited North America, providing early descriptions of
Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the province of Ontario in Canada and the state of New York in the United States. The largest of the three is Horseshoe Fall ...
and the
Saint Anthony Falls Saint Anthony Falls, or the Falls of Saint Anthony ( dak, italics=no, Owámniyomni, ) located at the northeastern edge of downtown Minneapolis, Minnesota, is the only natural major waterfall on the Mississippi River. Throughout the mid-to-late 1 ...
. The geographer Brian J. Hudson argues that it was uncommon to specifically name waterfalls until the 1700s. The trend of Europeans specifically naming falls was in tandem with increased scientific focus on nature, the rise of
Romanticism Romanticism (also known as the Romantic movement or Romantic era) was an artistic, literary, musical, and intellectual movement that originated in Europe towards the end of the 18th century, and in most areas was at its peak in the approximate ...
, and increased importance of hydropower with the
Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
. European explorers often ignored the names native peoples had given the falls in favor of a "European" name; for instance, David Livingstone named
Victoria Falls Victoria Falls ( Lozi: ''Mosi-oa-Tunya'', "The Smoke That Thunders"; Tonga: ''Shungu Namutitima'', "Boiling Water") is a waterfall on the Zambezi River in southern Africa, which provides habitat for several unique species of plants and anim ...
after
Queen Victoria Victoria (Alexandrina Victoria; 24 May 1819 – 22 January 1901) was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death in 1901. Her reign of 63 years and 216 days was longer than that of any previo ...
, though it was already known as Mosi-oa-Tunya. Many waterfalls have descriptive names which can come from the river they are on, places they are near, their features, or events that happened near them. Some countries that were colonized by European nations have taken steps to return names to waterfalls previously renamed by European explorers. Exploration of waterfalls continues; the Gocta Cataracts were first announced to the world in 2006. Waterfalls can pose major barriers to travel. Canals are sometimes built as a method to go around them, other times things must be physically carried around or a railway built. In 1885, the geographer George Chisholm wrote that, "The most signal example of the effect of waterfalls and rapids in retarding the development of civilisation is undoubtedly presented by the continent of Africa, the 'darkness' of which is almost entirely due to this cause."


Development and tourism

Waterfalls are often visited by people simply to see them. Hudson theorizes that they make good tourism sites because they are generally considered beautiful and are relatively uncommon. Activities at waterfalls can include bathing, swimming, photography,
rafting Rafting and whitewater rafting are recreational outdoor activities which use an inflatable raft to navigate a river or other body of water. This is often done on whitewater or different degrees of rough water. Dealing with risk is often a ...
,
canyoning Canyoning (canyoneering in the United States, kloofing in South Africa) is a type of mountaineering that involves travelling in canyons using a variety of techniques that may include other outdoor activities such as walking, scrambling, climbin ...
,
abseiling Abseiling ( ; ), also known as rappelling ( ; ), is the controlled descent of a steep slope, such as a rock face, by moving down a rope. When abseiling the person descending controls their own movement down the rope, in contrast to low ...
, rock climbing, and ice climbing. Waterfalls can also be sites for generating hydroelectric power and can hold good fishing opportunities. Wealthy people were known to visit areas with features such as waterfalls at least as early as in
Ancient Rome In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
and China. However, many waterfalls were essentially inaccessible due to the treacherous terrain surrounding them until improvements began to be made such as paths to the falls, becoming common across the United Kingdom and America in the 1800s and continuing through the 1900s and into the 21st century. Remote waterfalls are now often visited by air travel. Human development has also threatened many waterfalls. For instance, the
Guaíra Falls Guairá Falls ( es, Saltos del Guairá, pt, Salto das Sete Quedas do Guaíra) were a series of immense waterfalls on the Paraná River along the border between Paraguay and Brazil. The falls ceased to exist in 1982 when they were inundated by the ...
, once one of the most powerful waterfalls in the world, were submerged in 1982 by a human-made dam, as were the
Ripon Falls Ripon Falls at the northern end of Lake Victoria in Uganda was formerly considered the source of the river Nile. In 1862–3 John Hanning Speke Captain John Hanning Speke (4 May 1827 – 15 September 1864) was an English explorer and offi ...
in 1952. Conversely, other waterfalls have seen significantly lower water levels as a result of diversion for
hydroelectricity Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
, such as the
Tyssestrengene Tyssestrengene are waterfalls east of the village of Tyssedal in Ullensvang Municipality, in Vestland county, Norway. The waterfalls are fed by the Tysso River before flowing down into the lake Ringedalsvatnet. The Trolltunga cliff is located n ...
in Norway. Development of the areas around falls as tourist attractions has also destroyed the natural scene around many of them. Waterfalls are included on thirty-eight
World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...
s and many others are protected by governments.


In culture

Waterfalls play a role in many cultures, as religious sites and subjects of art and music. Many artists have painted waterfalls and they are referenced in many songs, such as those of the
Kaluli people The Kaluli are a clan of illiterate how to talk" begins, and thus talk begins to be directed directly at the child. This does not exist in middle-class Anglo cultures, where infants are addressed somewhat like intentioned competent individuals f ...
in
Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...
.
Michael Harner Michael James Harner (April 27, 1929 – February 3, 2018) was an anthropologist, educator and author. His 1980 book, ''The Way of the Shaman: a Guide to Power and Healing,''Harner, Michael (1980) ''The Way of the Shaman''. San Francisco: Harper ...
titled his study of the
Jivaroan peoples The Jivaroan peoples are the indigenous peoples in the headwaters of the Marañon River and its tributaries, in northern Peru and eastern Ecuador. The tribes speak the Chicham languages. Their traditional way of life relies on gardening, and ...
of Ecuador ''The Jivaro: People of the Sacred Waterfalls.'' Artists such as those of the
Hudson River School The Hudson River School was a mid-19th century American art movement embodied by a group of landscape painters whose aesthetic vision was influenced by Romanticism. The paintings typically depict the Hudson River Valley and the surrounding area ...
and J. M. W. Turner and
John Sell Cotman John Sell Cotman (16 May 1782 – 24 July 1842) was an English marine and landscape painter, etcher, illustrator, author and a leading member of the Norwich School of painters. Born in Norwich, the son of a silk merchant and lace dealer, Co ...
painted particularly notable pictures of waterfalls in the 19th century. One of the versions of the
Shinto Shinto () is a religion from Japan. Classified as an East Asian religion by scholars of religion, its practitioners often regard it as Japan's indigenous religion and as a nature religion. Scholars sometimes call its practitioners ''Shintois ...
purification ceremony of
misogi is a Japanese Shinto practice of ritual purification by washing the entire body. Misogi is related to another Shinto purification ritual called '' Harae'' – thus both being collectively referred to as . Background Every year, many people ...
involves standing underneath a waterfall in ritual clothing. In Japan the
Nachi Falls in Nachikatsuura, Wakayama Prefecture, Japan, is one of the best-known waterfalls in Japan. With a drop of 133 meters (and 13 meters wide), it is the country's tallest water fall with single uninterrupted drop; however, the tallest waterfall ...
are a site of pilgrimage, as are falls near
Tirupati Tirupati () is a city in the Indian state of Andhra Pradesh. It is the administrative headquarters of the Tirupati district. The city is home to the important Hindu shrine of Tirumala Venkateswara Temple and other historic temples and is re ...
, India, and the
Saut-d'Eau Saut-d'Eau ( ht, Sodo) is a commune in the Mirebalais Arrondissement, in the Centre department of Haiti. It has 34,885 inhabitants. Its name is French for 'waterfall', named after a large waterfall called 'Le Saut'. It is said that this water ...
, Haiti. The
Otavalos The Otavalos are an indigenous people native to the Andean mountains of Imbabura Province in northern Ecuador. The Otavalos also inhabit the city of Otavalo in that province. Commerce and handcrafts are among the principal economic activities o ...
use Piguchi waterfall as part of the Churru ritual which serves as a coming of age ceremony. Many waterfalls in Africa were places of worship for the native peoples and got their names from gods in the local religion.


List

260px, Shaki_Waterfall_in_Armenia_.html" ;"title="Armenia.html" ;"title="Shaki Waterfall in Armenia">Shaki Waterfall in Armenia ">Armenia.html" ;"title="Shaki Waterfall in Armenia">Shaki Waterfall in Armenia There are thousands of waterfalls in the world, though no exact number has been calculated. The World Waterfall Database lists 7,827 as of 2013, but this is likely incomplete; as noted by Hudson, over 90% of their listings are in North America. Many guidebooks to local waterfalls have been published. There is also no agreement how to measure the height of a waterfall, or even what constitutes one. Angel Falls in Venezuela is the List of waterfalls by height, tallest waterfall in the world, the Khone Phapheng Falls in Laos are the widest, and the Inga Falls on the Congo River are the biggest List of waterfalls by flow rate, by flow rate, while the
Dry Falls Dry Falls is a scalloped precipice with four major alcoves, in central Washington scablands. This cataract complex is on the opposite side of the Upper Grand Coulee from the Columbia River, and at the head of the Lower Grand Coulee, northern ...
in
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
are the largest confirmed waterfalls ever. The highest known subterranean waterfall is in Vrtoglavica Cave in
Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, an ...
. The largest known oceanic waterfall is the
Denmark Strait cataract The Denmark Strait cataract is an undersea waterfall found on the western side of the Denmark Strait in the Atlantic Ocean, on the Arctic Circle between Iceland and Greenland. It is the world's highest underwater waterfall, with water falling al ...
.
Artificial waterfall An artificial waterfall is a water feature or fountain which imitates a natural waterfall. Artificial waterfalls have long been featured in traditional Japanese gardens, where they can serve to highlight a scene or to provide focus. The classic ...
s are
water feature In landscape architecture and garden design, a water feature is one or more items from a range of fountains, jeux d'eau, pools, ponds, rills, artificial waterfalls, and streams. Before the 18th century they were usually powered by gravity, ...
s or
fountain A fountain, from the Latin "fons" (genitive "fontis"), meaning source or spring, is a decorative reservoir used for discharging water. It is also a structure that jets water into the air for a decorative or dramatic effect. Fountains were ori ...
s that imitate a natural waterfall.Susan C. Anderson (Editor), Bruce Tabb (Editor), ''Water, Leisure and Culture: European Historical Perspectives'', Berg Publishers, 2002, , page 122 The
Cascata delle Marmore The Cascata delle Marmore () or Marmore Falls is a man-made waterfall created by the ancient Romans. Its total height is 165 m (541 feet), making it the tallest man-made waterfall in the world. It is located 7.7 km from Terni, a prov ...
is the tallest artificially built waterfall at .


References


Bibliography

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External links

{{Authority control Fluvial landforms