Rapids are sections of a river where the river bed has a relatively steep
gradient
In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gradi ...
, causing an increase in water
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
and
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
.
Rapids are
hydrological
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is calle ...
features between a ''run'' (a smoothly flowing part of a
stream
A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...
) and a ''
cascade
Cascade, Cascades or Cascading may refer to:
Science and technology Science
*Cascade waterfalls, or series of waterfalls
* Cascade, the CRISPR-associated complex for antiviral defense (a protein complex)
* Cascade (grape), a type of fruit
* Bioc ...
''. Rapids are characterized by the river becoming shallower with some
rock
Rock most often refers to:
* Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids
* Rock music, a genre of popular music
Rock or Rocks may also refer to:
Places United Kingdom
* Rock, Caerphilly, a location in Wales ...
s exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white color, forming what is called "
whitewater
Whitewater forms in a rapid context, in particular, when a river's gradient changes enough to generate so much turbulence that air is trapped within the water. This forms an unstable current that froths, making the water appear opaque and ...
". Rapids occur where the
bed material is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length. Rapids cause
water aeration
Water aeration is the process of increasing or maintaining the oxygen saturation of water in both natural and artificial environments. Aeration techniques are commonly used in pond, lake, and reservoir management to address low oxygen levels or a ...
of the stream or river, resulting in better water quality.
Rapids are categorized in
classes, generally running from I to VI. A Class 5 rapid may be categorized as Class 5.1-5.9. While Class I rapids are easy to navigate and require little maneuvering, Class VI rapids pose threat to life with little or no chance for rescue.
River rafting
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 wate ...
sports are carried out where many rapids are present in the course.
File:Rapids before the Rhine Falls.jpg, Rapids featuring whitewater, close to the Rhine Falls
, photo = File:SBB RABe 514 DTZ Rheinfall.jpg
, photo_width = 280
, photo_caption = Rhine Falls with Rheinfall Bridge and Laufen Castle
, location = On the border between the cantons of Schaffhausen and Zürich next to Schaffhausen, i ...
File:Violent water below Niagara Falls.jpg, Violent water below 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 Falls, ...
File:RapidsonMississippiRiverOntario.jpg, Rapids on the Mississippi River (Ontario)
The Mississippi River is a tributary of the Ottawa River in Eastern Ontario, Canada which has no relation with the Mississippi River in the United States. It is in length from its source at Mackavoy Lake, has a drainage area of , and has a mean ...
in Pakenham, Ontario, Canada.
File:Rapids on Maumee River above Toledo, Ohio - DPLA - 84b5711224c89b44832b7e7d0f6c27c9 (page 1).jpg, Historical image of the river rapids on the Maumee River
The Maumee River (pronounced ) ( sjw, Hotaawathiipi; mia, Taawaawa siipiiwi) is a river running in the United States Midwest from northeastern Indiana into northwestern Ohio and Lake Erie. It is formed at the confluence of the St. Joseph and ...
in Ohio
File:Uusimaa, Finland - panoramio - pan-opticon (22).jpg, The Kuhakoski
Kuhakoski (; literally meaning "zander rapids") is a rapids near the village of Perttula in Nurmijärvi, Finland. rapids in Uusimaa
Uusimaa (; sv, Nyland, ; both lit. 'new land') is a region of Finland. It borders the regions of Southwest Finland, Tavastia Proper (Kanta-Häme), Päijänne Tavastia (Päijät-Häme), and Kymenlaakso. Finland's capital and largest city, He ...
, Finland
Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...
See also
*
Fluid dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) an ...
*
International scale of river difficulty - for classification of rapids
*
Rheophile
A rheophile is an animal that prefers to live in fast-moving water.
Examples of rheophilic animals
Insects
*Many aquatic insects living in riffles require current to survive.
*'' Epeorus sylvicola'', a rheophilic mayfly species ( Ephemeroptera ...
- organisms that live in fast-flowing water
*
Riffle
A riffle is a shallow landform in a flowing channel. Colloquially, it is a shallow place in a river where water flows quickly past rocks. However, in geology a riffle has specific characteristics.
Topographic, sedimentary and hydraulic indica ...
- A fast-moving portion of a stream without the vigor of a rapid
*
River rapids ride
A river rapids ride (or river rafting ride) is an amusement ride that simulates whitewater rafting.
History
The river rapids ride concept was proposed by Bill Crandall (general manager of AstroWorld in Houston) and developed by Intamin. AstroW ...
References
*
External links
Rapids entryin
National Geographic
''National Geographic'' (formerly the ''National Geographic Magazine'', sometimes branded as NAT GEO) is a popular American monthly magazine published by National Geographic Partners. Known for its photojournalism, it is one of the most widely ...
's encyclopedia
Fluvial landforms
Limnology
Rivers
Water streams
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