Fluvial processes

Short description: Processes associated with rivers and streams

Deep, eroding glaciofluvial deposits alongside the Matanuska River, Alaska

In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term "glaciofluvial" or "fluvioglacial" is used.[1][2]

## Contents

* 1 Fluvial processes
* 2 See also
* 2.1 Fluvial processes
* 2.2 Fluvial channel patterns
* 2.3 Fluvial landforms
* 2.4 Related terms
* 3 References

## Fluvial processes

The White River is so named due to the clay it picks up in the Badlands of South Dakota. Here it flows into the Missouri River and colors it with clay.

Fluvial processes include the motion of sediment and erosion or deposition on the river bed.[3][4]

The movement of water across the stream bed exerts a shear stress directly onto the bed. If the cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. In addition, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed (abrasion). At the same time the fragments themselves are ground down, becoming smaller and more rounded (attrition).

Sediment in rivers is transported as either bedload (the coarser fragments which move close to the bed) or suspended load (finer fragments carried in the water). There is also a component carried as dissolved material.

For each grain size there is a specific flow velocity at which the grains start to move, called entrainment velocity. However the grains will continue to be transported even if the velocity falls below the entrainment velocity due to the reduced (or removed) friction between the grains and the river bed. Eventually the velocity will fall low enough for the grains to be deposited. This is shown by the Hjulström curve.

A river is continually picking up and dropping solid particles of rock and soil from its bed throughout its length. Where the river flow is fast, more particles are picked up than dropped. Where the river flow is slow, more particles are dropped than picked up. Areas where more particles are dropped are called alluvial or flood plains, and the dropped particles are called alluvium.

Even small streams make alluvial deposits, but it is in floodplains and deltas of large rivers that large, geologically-significant alluvial deposits are found.

The amount of matter carried by a large river is enormous. It has been estimated that the Mississippi River annually carries 406 million tons of sediment to the sea,[5] the Yellow River 796 million tons, and the Po River in Italy 67 million tons.[6] The names of many rivers derive from the color that the transported matter gives the water. For example, the Yellow River (Huang He) in China is named after the hue of the sediment it carries,[7] and the White Nile is named for the clay it carries.

## See also

* Body of water

### Fluvial processes

* Earth:Bradshaw model - Geographical model of river characteristics
* Chemistry:Corrosion (solution)
* Earth:Erosion
* Earth:Downcutting - Process of deepening a stream channel by erosion of the bottom material
* Earth:Saltation (geology) - Particle transport by fluids
* Chemistry:Suspension - Heterogeneous mixture of solid particles dispersed in a medium

### Fluvial channel patterns

* Biology:Anastomosis
* Earth:Braided river - Network of river channels
* Earth:Channel pattern - Characteristic geometry of a channel system
* Meandering river

### Fluvial landforms

* Earth:Channel (geography) - Type of landform in which part of a body of water is confined to a relatively narrow but long region
* Earth:Confluence
* Earth:Cut bank - Outside bank of a water channel, which is continually undergoing erosion
* Earth:Crevasse splay - Sediment deposited on a floodplain by a stream which breaks its levees
* Earth:Drainage basin - Land area where water converges to a common outlet (watershed)
* Earth:Esker
* Earth:Floodplain
* Fluvial landforms of streams
* Earth:Fluvial terrace - Elongated terraces that flank the sides of floodplains and river valleys
* Earth:Canyon (Gorge)
* Earth:Gully - Landform created by running water and/or mass movement eroding sharply into soil
* Earth:Island
* Levee § Natural levees
* Earth:Meander
* Earth:Oxbow lake - U-shaped lake or pool left by an ancient river meander
* Earth:Plunge pool - Depression at the base of a waterfall
* Earth:Point bar - Landform related to streams and rivers
* Earth:Riffle - Shallow landform in a flowing channel
* Earth:River
* Earth:River island - Exposed landmass within a river
* Earth:River valley, also known as vale
* Earth:Shoal, also known as bar - Natural submerged sandbank that rises from a body of water to near the surface
* Earth:Spring (hydrology) - Point at which water emerges from an aquifer to the surface
* Earth:Stream
* Earth:Stream pool - Deep and slow-moving stretch of a watercourse
* Earth:Waterfall
* Earth:Yazoo stream - Hydrologic term

### Related terms

* lacustrine – of or relating to a lake
* maritime – of or relating to a sea
* oceanic – of or relating to an ocean
* palustrine – of or relating to a marsh

## References

1. ↑ Glossary of Geology (5th revised ed.). Alexandria, Virginia: American Geological Institute. 2011. pp. 800. ISBN 978-3642066214. OCLC 751527782. https://store.americangeosciences.org/glossary-of-geology-fifth-edition-revised.html.
2. ↑ Wilson, W.E. & Moore, J.E. 2003. Glossary of Hydrology, American Geological Institute, Springer, 248pp.
3. ↑ Charlton, Ro (2008). Fundamentals of fluvial geomorphology. London: Rutledge. p. 234. ISBN 978-0-415-33454-9. https://archive.org/details/fundamentalsfluv00char.
4. ↑ Wohl, Ellen (2014). Rivers in the Landscape: Science and Management. Wiley-Blackwell. p. 330. ISBN 978-1118414897.
5. ↑ Mathur, Anuradha; Dilip da Cunha (2001). Mississippi Floods: Designing a Shifting Landscape. New Haven, CT: Yale University Press. ISBN 0-300-08430-7
6. ↑ Dill, William A. (1990). Inland fisheries of Europe. Rome, Italy: UN Food and Agriculture Organization. ISBN 92-5-102999-7. http://www.fao.org/docrep/009/t0377e/t0377e00.htm
7. ↑ MOSTERN, RUTH; HORNE, RYAN M. (2021). The Yellow River: A Natural and Unnatural History. Yale University Press. pp. 33. doi:10.2307/j.ctv1vbd1d8.7. ISBN 978-0-300-23833-4. https://www.jstor.org/stable/j.ctv1vbd1d8.

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* t
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Sediment transport

Water|

* Coastal sediment transport
* Fluvial processes
* Bed load
* Suspended load
* Bed material load

Glacial|

* Glacial flour
* Glacial outwash
* Braided river
* Moraine
* Esker
* Drumlin

Hillslope|

* Soil creep
* Landslide

Aeolian|

* Dune

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