rapid adj

1 done or occurring in a brief period of time; "a rapid rise through the ranks"

2 characterized by speed; moving with or capable of moving with high speed; "a rapid movment"; "a speedy car"; "a speedy errand boy" [syn: speedy] n : a part of a river where the current is very fast

English

Etymology

rapidus

Pronunciation

• /ˈræpɪd/

Adjective

1. Describes a process or concept which occurs quickly.

Translations

Noun

1. often in plural a rough section of a river or stream which is difficult to navigate due to the swift and turbulent motion of the water.

Translations

Related terms

• rape
• rapt

Derived terms

• rapidity
• rapidly
• rapidness

A rapid is a section of a river where the river bed has a relatively steep gradient causing an increase in water flow and turbulence. A rapid is a hydrological feature between a run (a smoothly flowing part of a stream) and a cascade. A rapid is characterised by the river becoming shallower and having 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 colour, 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.

See also

• Fluid dynamics - for academic explanation.
• 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 vigour of a rapid
• Whitewater - for factors related to rapids.

References

• Mason, Bill. Path of the Paddle, 1984, Northword Press, Minoqua, WI.

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