Rapids

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Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence.

Rapids are hydrological features between a run (a smoothly flowing part of a stream) and a cascade. Rapids are characterized by the river becoming shallower with some rocks 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". 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 of the stream or river, resulting in better water quality.

Rapids are categorized in

sports are carried out where many rapids are present in the course.

• 
  Rapids featuring whitewater, close to the Rhine Falls
• 
  Violent water below Niagara Falls
• 
  Rapids on the

  Pakenham, Ontario

  , Canada.
• 
  Historical image of the river rapids on the Maumee River in Ohio
• 
  The Kuhakoski rapids in Uusimaa, Finland

See also

• Fluid dynamics
• International scale of river difficulty - for classification of rapids
• Rheophile - organisms that live in fast-flowing water
• Riffle - A fast-moving portion of a stream without the vigor of a rapid
• River rapids ride

References

• Mason, Bill (1984). Path of the Paddle. Northword Press.
  ISBN 9781559710046
  .

External links

• Rapids entry in National Geographic's encyclopedia