Rapid
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AnnaFrance
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[[WP:AWB/T|Typo fixing]], typos fixed: catagorized → categorized (2) using [[Project:AutoWikiBrowser|AWB]]
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[[Image:Rapids.jpg|thumb|240px|Rapids featuring whitewater, close to the Rhine Falls]]
[[Image:!downstream river1.jpg |thumb|240px|right| Violent water below Niagara Falls]]
A '''rapid''' is a section of a [[river]] where the river bed has a relatively steep [[stream gradient|gradient]] causing an increase in water [[Volumetric flow rate|flow]] and [[turbulence]]. A rapid is a [[hydrology|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 [[Rock (geology)|rock]]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 colour, forming what is called "[[whitewater]]". Rapids occur where the [[stream bed|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 are categorized in classes. These being Class I-VI. A Class 5 rapid may be categorized as Class 5.1-5.9 respectively.
==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.
[[Category:Whitewater sports]]
[[Category:Water streams]]
[[Category:Rapids| ]]
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