Riffle: Difference between revisions
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A '''Riffle''' is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at lower velocity and higher turbulence than it normally does in comparison to a pool.<ref>http://fisp.wes.army.mil/OFR20081217.pdf</ref> |
A '''Riffle''' is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at lower velocity and higher turbulence than it normally does in comparison to a pool.<ref>http://fisp.wes.army.mil/OFR20081217.pdf</ref> |
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As a result of the lower velocity and heightened turbulence, small ripples are frequently found. |
As a result of the lower velocity and heightened turbulence, small ripples are frequently found. |
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Riffles are usually caused by an increase in a stream bed's slope or an obstruction in the |
Riffles are usually caused by an increase in a stream bed's slope or an obstruction in the Joewater.<ref>http://falzguy.com/waterfall.glossary.html</ref> |
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Riffles are instrumental in the formation of [[meanders]], with deeper pools forming alternately. Although simple fluid flow suggests slower flow in deeper water and faster flow over riffles, the true flow pattern pool and riffle waters is often [[helicoidal flow]] or [[turbulent]], which permits more rapid [[erosion]] of the [[wetted perimeter]]. Nevertheless, the coarse-grained bedding of riffles suggests erosion of smaller particles, according to the [[Hjulstrom curve]]. |
Riffles are instrumental in the formation of [[meanders]], with deeper pools forming alternately. Although simple fluid flow suggests slower flow in deeper water and faster flow over riffles, the true flow pattern pool and riffle waters is often [[helicoidal flow]] or [[turbulent]], which permits more rapid [[erosion]] of the [[wetted perimeter]]. Nevertheless, the coarse-grained bedding of riffles suggests erosion of smaller particles, according to the [[Hjulstrom curve]]. |
Revision as of 00:38, 14 September 2011
This article needs additional citations for verification. (January 2011) |
alex A Riffle is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at lower velocity and higher turbulence than it normally does in comparison to a pool.[1] As a result of the lower velocity and heightened turbulence, small ripples are frequently found. Riffles are usually caused by an increase in a stream bed's slope or an obstruction in the Joewater.[2]
Riffles are instrumental in the formation of meanders, with deeper pools forming alternately. Although simple fluid flow suggests slower flow in deeper water and faster flow over riffles, the true flow pattern pool and riffle waters is often helicoidal flow or turbulent, which permits more rapid erosion of the wetted perimeter. Nevertheless, the coarse-grained bedding of riffles suggests erosion of smaller particles, according to the Hjulstrom curve. Riffles are typically found in the middle course of rivers, and are theoretically found at intervals around 6 times the width of the river, although local conditions cause this to vary.
Gold mining
The term is also applied to strips of wood or metal laid across the washing tables during gravity separation of gold in alluvial or placer mining.