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Rocky stream in Italy
Frozen stream in Enäjärvi, Pori, Finland
Stream near Montriond in south-eastern France
Aubach (Wiehl) in North Rhine-Westphalia, Germany

A stream is a continuous body of surface water[1] flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks.

The flow of a stream is controlled by three inputs – surface runoff (from precipitation or meltwater), daylighted subterranean water, and surfaced groundwater (spring water). The surface and subterranean water are highly variable between periods of rainfall. Groundwater, on the other hand, has a relatively constant input and is controlled more by long-term patterns of precipitation.[2] The stream encompasses surface, subsurface and groundwater fluxes that respond to geological, geomorphological, hydrological and biotic controls.[3]

Streams are important as conduits in the water cycle, instruments in groundwater recharge, and corridors for fish and wildlife migration. The biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity. The study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography.[4]


Creek babbling through Benvoulin, Canada, wetlands
Wyming Brook in Sheffield, UK
A small stream in Lake Parramatta, Sydney
Stream with low gradient surrounded by natural riparian vegetation (Rhineland-Palatinate)
A low level stream in Macon County, Illinois



A brook is a stream smaller than a creek, especially one that is fed by a spring or seep. It is usually small and easily forded. A brook is characterised by its shallowness.



A creek (/krk/) or crick (/krɪk/):[5][6]

In hydrography, gut is a small creek;[14] this is seen in proper names in eastern North America from the Mid-Atlantic states (for instance, The Gut in Pennsylvania, Ash Gut in Delaware,[15] and other streams)[16] down into the Caribbean (for instance, Guinea Gut, Fish Bay Gut, Cob Gut, Battery Gut and other rivers and streams in the United States Virgin Islands, in Jamaica (Sandy Gut,[17] Bens Gut River,[18] White Gut River), and in many streams and creeks of the Dutch Caribbean).[19]



A river is a large natural stream that is much wider and deeper than a creek and not easily fordable, and may be a navigable waterway.[20]



The linear channel between the parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Also called a swale.



A tributary is a contributory stream to a larger stream, or a stream which does not reach a static body of water such as a lake, bay or ocean[21] but joins another river (a parent river). Sometimes also called a branch or fork.[22]



A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel, and the phenomenon is known as river bifurcation. Distributaries are common features of river deltas, and are often found where a valleyed stream enters wide flatlands or approaches the coastal plains around a lake or an ocean. They can also occur inland, on alluvial fans, or where a tributary stream bifurcates as it nears its confluence with a larger stream. Common terms for individual river distributaries in English-speaking countries are arm and channel.

Other names


There are a number of regional names for a stream.

Northern America


United Kingdom

A shoal that develops in a stream as sediment is deposited as the current slows or is impeded by wave action at the confluence.
A fork into two or more streams.
A depression created by constant erosion that carries the stream's flow.
The point at which the two streams merge. If the two tributaries are of approximately equal size, the confluence may be called a fork.
Drainage basin
(also known as a watershed in the United States) The area of land where water flows into a stream. A large drainage basin such as the Amazon River contains many smaller drainage basins.[34]
Lands adjacent to the stream that are subject to flooding when a stream overflows its banks.[34]
Headwaters or source
The part of a stream or river proximate to its source. The word is most commonly used in the plural where there is no single point source.[34]
The point on a stream's profile where a sudden change in stream gradient occurs.
The point at which the stream discharges, possibly via an estuary or delta, into a static body of water such as a lake or ocean.
A segment where the water is deeper and slower moving.
A turbulent, fast-flowing stretch of a stream or river.
A segment where the flow is shallower and more turbulent.
A large natural stream, which may be a waterway.[34]
A somewhat smoothly flowing segment of the stream.
The point at which a stream emerges from an underground course through unconsolidated sediments or through caves. A stream can, especially with caves, flow aboveground for part of its course, and underground for part of its course.[34]
Stream bed
The bottom of a stream.
Stream corridor
Stream, its floodplains, and the transitional upland fringe[35]
The water moving through a stream channel.[34]: Stream gauge: A site along the route of a stream or river, used for reference marking or water monitoring.[34]
The river's longitudinal section, or the line joining the deepest point in the channel at each stage from source to mouth.
The channel followed by a stream (a flowing body of water)[36] or the stream itself.[37][38][39] In the UK, some aspects of criminal law, such as the Rivers (Prevention of Pollution) Act 1951, specify that a watercourse includes those rivers which are dry for part of the year.[40] In some jurisdictions, owners of land over which the water flows may have the legal right to use or retain some or much of that water.[41] This right may extend to estuaries, rivers, streams, anabranches[42] and canals.[43]
Waterfall or cascade
The fall of water where the stream goes over a sudden drop called a knickpoint; some knickpoints are formed by erosion when water flows over an especially resistant stratum, followed by one less so. The stream expends kinetic energy in "trying" to eliminate the knickpoint.
Wetted perimeter
The line on which the stream's surface meets the channel walls.


Small tributary stream, Diamond Ridge, Alaska
Creek in Perisher Ski Resort, Australia

A stream's source depends on the surrounding landscape and its function within larger river networks. While perennial and intermittent streams are typically supplied by smaller upstream waters and groundwater, headwater and ephemeral streams often derive most of their water from precipitation in the form of rain and snow.[44] Most of this precipitated water re-enters the atmosphere by evaporation from soil and water bodies, or by the evapotranspiration of plants. Some of the water proceeds to sink into the earth by infiltration and becomes groundwater, much of which eventually enters streams. Some precipitated water is temporarily locked up in snow fields and glaciers, to be released later by evaporation or melting. The rest of the water flows off the land as runoff, the proportion of which varies according to many factors, such as wind, humidity, vegetation, rock types, and relief. This runoff starts as a thin film called sheet wash, combined with a network of tiny rills, together constituting sheet runoff; when this water is concentrated in a channel, a stream has its birth. Some creeks may start from ponds or lakes.

Stream in Alberta





To qualify as a stream, a body of water must be either recurring or perennial. Recurring (intermittent) streams have water in the channel for at least part of the year. A stream of the first order is a stream which does not have any other recurring or perennial stream feeding into it. When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream.



The gradient of a stream is a critical factor in determining its character and is entirely determined by its base level of erosion. The base level of erosion is the point at which the stream either enters the ocean, a lake or pond, or enters a stretch in which it has a much lower gradient, and may be specifically applied to any particular stretch of a stream.

In geological terms, the stream will erode down through its bed to achieve the base level of erosion throughout its course. If this base level is low, then the stream will rapidly cut through underlying strata and have a steep gradient, and if the base level is relatively high, then the stream will form a flood plain and meander.



Typically, streams are said to have a particular elevation profile, beginning with steep gradients, no flood plain, and little shifting of channels, eventually evolving into streams with low gradients, wide flood plains, and extensive meanders. The initial stage is sometimes termed a "young" or "immature" stream, and the later state a "mature" or "old" stream.



Meanders are looping changes of direction of a stream caused by the erosion and deposition of bank materials. These are typically serpentine in form. Typically, over time the meanders gradually migrate downstream. If some resistant material slows or stops the downstream movement of a meander, a stream may erode through the neck between two legs of a meander to become temporarily straighter, leaving behind an arc-shaped body of water termed an oxbow lake or bayou. A flood may also cause a meander to be cut through in this way.

Stream load


The stream load is defined as the solid matter carried by a stream. Streams can carry sediment, or alluvium. The amount of load it can carry (capacity) as well as the largest object it can carry (competence) are both dependent on the velocity of the stream.



Perennial or not


A perennial stream is one which flows continuously all year.[45]: 57  Some perennial streams may only have continuous flow in segments of its stream bed year round during years of normal rainfall.[46][47] Blue-line streams are perennial streams and are marked on topographic maps with a solid blue line.

Ephemeral stream


Generally, streams that flow only during and immediately after precipitation are termed ephemeral. There is no clear demarcation between surface runoff and an ephemeral stream,[45]: 58  and some ephemeral streams can be classed as intermittent—flow all but disappearing in the normal course of seasons but ample flow (backups) restoring stream presence — such circumstances are documented when stream beds have opened up a path into mines or other underground chambers.[48]

According to official U.S. definitions, the channels of intermittent streams are well-defined,[49] as opposed to ephemeral streams, which may or may not have a defined channel, and rely mainly on storm runoff, as their aquatic bed is above the water table.[50] An ephemeral stream does not have the biological, hydrological, and physical characteristics of a continuous or intermittent stream.[50] The same non-perennial channel might change characteristics from intermittent to ephemeral over its course.[50]

Intermittent or seasonal stream

Australian creek, low in the dry season, carrying little water. The energetic flow of the stream had, in flood, moved finer sediment further downstream. There is a pool to lower right and a riffle to upper left of the photograph.
A small, narrow stream flowing down a tiny dell in Pennsylvania.

Washes can fill up quickly during rains, and there may be a sudden torrent of water after a thunderstorm begins upstream, such as during monsoonal conditions. In the United States, an intermittent or seasonal stream is one that only flows for part of the year and is marked on topographic maps with a line of blue dashes and dots.[45]: 57–58  A wash, desert wash, or arroyo is normally a dry streambed in the deserts of the American Southwest, which flows after sufficient rainfall.

In Italy, an intermittent stream is termed a torrent (Italian: torrente). In full flood the stream may or may not be "torrential" in the dramatic sense of the word, but there will be one or more seasons in which the flow is reduced to a trickle or less. Typically torrents have Apennine rather than Alpine sources, and in the summer they are fed by little precipitation and no melting snow. In this case the maximum discharge will be during the spring and autumn.

An intermittent stream can also be called a winterbourne in Britain, a wadi in the Arabic-speaking world or torrente or rambla (this last one from arabic origin) in Spain and Latin America. In Australia, an intermittent stream is usually called a creek and marked on topographic maps with a solid blue line.[citation needed]

Consequential or not


There are five generic classifications:

  • Consequent streams are streams whose course is a direct consequence of the original slope of the surface[51] upon which it developed, i.e., streams that follow slope of the land over which they originally formed.

  • Subsequent streams are streams whose course has been determined by selective headward erosion along weak strata. These streams have generally developed after the original stream. Subsequent streams developed independently of the original relief of the land and generally follow paths determined by the weak rock belts.
  • Resequent streams are streams whose course follows the original relief, but at a lower level than the original slope (e.g., flows down a course determined by the underlying strata in the same direction). These streams develop later and are generally a tributary to a subsequent stream.[52]
  • Obsequent streams are streams flowing in the opposite direction of the consequent drainage.
  • Insequent streams have an almost random drainage often forming dendritic patterns. These are typically tributaries and have developed by a headward erosion on a horizontally stratified belt or on homogeneous rocks. These streams follow courses that apparently were not controlled by the original slope of the surface, its structure or the type of rock.

Drainage basins


The extent of land basin drained by a stream is termed its drainage basin (also known in North America as the watershed and, in British English, as a catchment).[53] A basin may also be composed of smaller basins. For instance, the Continental Divide in North America divides the mainly easterly-draining Atlantic Ocean and Arctic Ocean basins from the largely westerly-flowing Pacific Ocean basin. The Atlantic Ocean basin, however, may be further subdivided into the Atlantic Ocean and Gulf of Mexico drainages. (This delineation is termed the Eastern Continental Divide.) Similarly, the Gulf of Mexico basin may be divided into the Mississippi River basin and several smaller basins, such as the Tombigbee River basin. Continuing in this vein, a component of the Mississippi River basin is the Ohio River basin, which in turn includes the Kentucky River basin, and so forth.



Stream crossings are where streams are crossed by roads, pipelines, railways, or any other thing which might restrict the flow of the stream in ordinary or flood conditions. Any structure over or in a stream which results in limitations on the movement of fish or other ecological elements may be an issue.

See also



  1. ^ Langbein, W.B.; Iseri, Kathleen T. (1995). "Hydrologic Definitions: Stream". Manual of Hydrology: Part 1. General Surface-Water Techniques (Water Supply Paper 1541-A). Reston, VA: USGS. Archived from the original on 2012-05-09.
  2. ^ Basic Biology (16 January 2016). "River".
  3. ^ Alexander, L. C., Autrey, B., DeMeester, J., Fritz, K. M., Golden, H. E., Goodrich, D. C., ... & McManus, M. G. (2015). Connectivity of streams and wetlands to downstream waters: review and synthesis of the scientific evidence (Vol. 475). EPA/600/R-14.
  4. ^ "What is hydrology and what do hydrologists do?" Archived 2014-02-22 at the Wayback Machine U.S. Geological Survey (USGS). Atlanta, GA. 2009-05-13.
  5. ^ "creek". dictionary.com. Dictionary.com, LLC. Retrieved 16 May 2019. kreek, krik
  6. ^ "crick". English Oxford Living Dictionaries. Oxford University Press. Archived from the original on May 18, 2019. Retrieved 18 May 2019. Northern, North Midland, and Western U.S.
  7. ^ "creek". oxforddictionaries.com. Oxford University Press. Archived from the original on September 24, 2016. Retrieved 18 May 2019. British...especially an inlet...(whereas) NZ, North American, Australian...stream or minor tributary.
  8. ^ "(US) creek". English Oxford Living Dictionaries. Oxford University Press. Archived from the original on September 24, 2016. Retrieved 18 May 2019. North American, Australian, NZ...A stream, brook, or minor tributary of a river.
  9. ^ "creek". Dictionary.com. Dictionary.com, LLC. Retrieved 18 May 2019. U.S., Canada , and Australia…a stream smaller than a river.
  10. ^ "creek". Collins Dictionary. Retrieved 18 May 2019. US, Canadian, Australian and New Zealand a small stream or tributary
  11. ^ "creek". Macmillan Dictionary. Springer Nature Limited. Retrieved 18 May 2019. a narrow stream
  12. ^ [7][8][9][10][11]
  13. ^ Spruce Creek Association. Kittery, ME. "About the Spruce Creek Watershed." Archived 2008-07-03 at the Wayback Machine Accessed 2010-10-02.
  14. ^ "Gut (definition)". Merriam-Webster Dictionary. Retrieved August 8, 2014.
  15. ^ "Ash Gut". Anyplace America. Retrieved August 14, 2014.
  16. ^ "Feature Query Results". Geographic Names Information System (GNIS). United States Geological Survey. Retrieved August 14, 2014.
  17. ^ "Sandy Gut, Jamaica". iTouch Map. Retrieved August 9, 2014.
  18. ^ "Bens Gut River". Geoview. Retrieved August 9, 2014.
  19. ^ "White Gut River (Jamaica)". Gazettering.com. Retrieved August 9, 2014.
  20. ^ Wetzel, Robert G. (2001). Limnology: Lake and river ecosystems (3rd ed.). San Diego: Academic Press. ISBN 978-0127447605. OCLC 46393244.
  21. ^ Krebs, Robert E. (2003). The Basics of Earth Science. Greenwood Publishing Group. ISBN 978-0-313-31930-3.
  22. ^ Bisson, Peter and Wondzell, Steven. "Olympic Experimental State Forest Synthesis of Riparian Research and Monitoring" Archived 2022-08-13 at the Wayback Machine, United States Forest Service, p. 15 (December 1, 2009).
  23. ^ "OED Online -Branch". Oxford University Press. June 2017. Retrieved 6 July 2017.
  24. ^ a b "Derek Watkin's USGS Analysis". 25 July 2011. Retrieved 26 November 2018.
  25. ^ Steigerwalt, Nancy M.; Cichra, Charles E.; Baker, Shirley M. (2008). "Composition and Distribution of Aquatic Invertebrate Communities on Snags in a North Central Florida, USA, Spring-Run Stream". Florida Scientist. 71 (3): 273–286. JSTOR 24321406.
  26. ^ "OED Online – Beck". Oxford University Press. June 2017. Retrieved 6 July 2017.
  27. ^ "OED Online – Bourne". Oxford University Press. June 2017. Retrieved 6 July 2017.
  28. ^ "OED Online – Brook". Oxford University Press. June 2017. Retrieved 6 July 2017.
  29. ^ "OED Online – Burn". Oxford University Press. June 2017. Retrieved 6 July 2017.
  30. ^ "OED Online – Gill". Oxford University Press. June 2017. Retrieved 6 July 2017.
  31. ^ "OED Online – Nant". Oxford University Press. June 2017. Retrieved 6 July 2017.
  32. ^ "OED Online – Rivulet". Oxford University Press. June 2017. Retrieved 6 July 2017.
  33. ^ "OED Online – Sike". Oxford University Press. June 2017. Retrieved 6 July 2017.
  34. ^ a b c d e f g "USGS Water Science Glossary of Terms". United States Geological Survey. 26 November 2018.
  35. ^ "Stream Corridor Structure" Archived 2015-04-02 at the Wayback Machine Adapted from Stream Corridor Restoration: Principles, Processes, and Practices
  36. ^ Shannonhouse, Royal G. (1961). "Some Principles of Water Law in the Southeast". Mercer Law Review. 13: 344.
  37. ^ "Definition of WATERCOURSE". Merriam-Webster. 2022-03-18. Retrieved 2022-04-05.
  38. ^ "watercourse". definition in the Cambridge English Dictionary. 2016-03-07. Retrieved 2022-04-05.
  39. ^ Lewis, Roy; Hilton, John Buxton; Fallon, Jennifer (2022-04-05). "Watercourse definition and meaning". Collins English Dictionary. Retrieved 2022-04-05.
  40. ^ "Rivers (Prevention of Pollution) Act 1951". legislation.gov.uk. Retrieved 25 August 2016.
  41. ^ Jones, J.G. (1965). "Water Rights in Louisiana". Louisiana Law Review. 16 (3): 500.
  42. ^ North, Colin P. (2007). "Recognition of the Sedimentary Architecture of Dryland Anabranching (Anastomosing) Rivers". Journal of Sedimentary Research. 77 (11): 925–938. Bibcode:2007JSedR..77..925N. doi:10.2110/jsr.2007.089.
  43. ^ "Watercourse". FEMA. Archived from the original on 2017-07-07. Retrieved 2017-12-15.
  44. ^ "Streams | Rivers & Streams | US EPA". archive.epa.gov. Retrieved 2021-10-14.
  45. ^ a b c Meinzer, Oscar E. (1923). Outline of ground-water hydrology, with definitions. Washington, DC: USGS. doi:10.3133/wsp494. Archived from the original on 2017-07-09. Water Supply Paper 494.
  46. ^ Meinzer, Oscar E. (1923). Outline of ground-water hydrology, with definitions. Washington, DC: US Geological Survey (USGS). p. 57. doi:10.3133/wsp494. Archived from the original on 2017-07-09. Water Supply Paper 494.
  47. ^ "OSM – COALEX State Inquiry Report 97". Archived from the original on 2012-04-15. Retrieved 2011-12-11.
  48. ^ Black Creek (Susquehanna River)#Hydrology and climate, 'Black Creek is an ephemeral stream. It used to drain an area between Turtle Creek and the Susquehanna River, but now loses its flow to underground mines via broken bedrock. Its channel is also disrupted by strip mines and rock piles.', 14 Nov 2016.
  50. ^ a b c "Stream Identification Method and Rating Form: Definitions". Identification Methods for the Origins of Intermittent and Perennial streams, Version 3.1 (PDF). North Carolina Department of Environment and Natural Resources, Division of Water Quality. 28 February 2005. p. 2. Retrieved 28 February 2021.
  51. ^ "consequent stream". Dictionary.com. Retrieved 2008-04-24.
  52. ^ "Definition of RESEQUENT". www.merriam-webster.com. Retrieved 2022-12-14.
  53. ^ Langbein, W.B.; Iseri, Kathleen T. (1995). "Hydrologic Definitions: Watershed". Manual of Hydrology: Part 1. General Surface-Water Techniques (Water Supply Paper 1541-A). Reston, VA: USGS. Archived from the original on 2012-05-09.