- Riffle-pool sequence
In a flowing
stream a riffle-pool sequence develops as an area of alternating areas of relatively shallow and deeper water.Riffle s describe shallow water where the flow is rippling overgravel deposits whereas pools are deeper and calmer areas. Riffle-pool sequences develop in astream carrying gravel or coasersediment s. Streams with onlysand orsilt laden beds do not develop the feature.Fact|date=February 2008 The sequence within a streambed commonly occurs at intervals of from 5 to 7 stream widths. Meandering streams with relatively coarse bed load tend to develop a riffle-pool sequence with pools in the outsides of the bends and riffles in the "crossovers" between onemeander to the next on the opposite margin of the stream. The pools are areas of active erosion and the material eroded tends to be deposited in the riffle area between.References
* [http://www.fhwa.dot.gov/ENVIRONMENT/fish2.htm Flow in Natural Streams, Federal Highway Administration]
* [http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/fluvial_systems/channel_types.html "Channel types" in Ritter, Michael E. (2006) "The Physical Environment: an Introduction to Physical Geography"]External links
* [http://web.archive.org/web/20060207000156/http://www.boquetriver.org/adoptriffle.html A description of the sequence]
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