For other meanings, see Rapid (disambiguation). A rapid is a section of a river where it loses elevation over a relatively short distance (that is, the stream gradient is locally steepened), causing an increase in water flow and (usually) turbulence. A rapid is a hydrological feature between a run and a cascade. A rapid is recognized by the river becoming shallower and having rocks exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and the water takes on 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

• Whitewater - for factors creating rapids
• International Scale of River Difficulty - for classification of rapids
• Fluid dynamics - for academic explanation

External links

• American Whitewater: International Scale of River Difficulty
• American Whitewater: Class I-III Benchmark Rapids
• American Whitewater: Class IV Benchmark Rapids
• American Whitewater: Class V Benchmark Rapids

References

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

Whitewater sports | Water streams

Stromschnelle | Koski (geologia) | Stroomversnelling | Стремнина