
A stream is a
body of water
A body of water or waterbody (often spelled water body) is any significant accumulation of water, generally on a planet's surface. The term most often refers to oceans, seas, and lakes, but it includes smaller pools of water such as ponds, wetla ...

with surface water flowing within the
bed
A bed is a piece of furniture
Furniture refers to movable objects intended to support various human activities such as seating (e.g., chairs, stools, and sofas), eating (table (furniture), tables), and sleeping (e.g., beds). Furniture ...
and
bank
A bank is a financial institution
Financial institutions, otherwise known as banking institutions, are corporation
A corporation is an organization—usually a group of people or a company—authorized by the State (polity), stat ...
s of a
channel
Channel, channels, channeling, etc., may refer to:
Geography
* Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water.
Australia
* Channel Country, region of outback Austr ...
. The flow of a stream is controlled by three inputs – surface water, subsurface water and groundwater. The surface and subsurface 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. The stream encompasses surface, subsurface and groundwater fluxes that respond to geological, geomorphological, hydrological and biotic controls.
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
river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

s.
Streams are important as conduits in the
water cycle
The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle
In ecology
Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships ...

, instruments in
groundwater recharge
Groundwater recharge or deep drainage or deep percolation is a process, where moves downward from to . Recharge is the primary method through which water enters an . This process usually occurs in the below plant s and, is often expressed as ...
, and corridors for
fish
Fish are aquatic
Aquatic means relating to water
Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the ...

and
wildlife
Wildlife traditionally refers to undomesticated animal
Animals (also called Metazoa) are multicellular
A multicellular organism is an organism
In biology, an organism () is any organic, life, living system that functi ...

migration. The biological
habitat
In ecology
Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers at the ...

in the immediate vicinity of a stream is called a
riparian zone
A riparian zone or riparian area is the interface between land and a river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground an ...
. Given the status of the ongoing
Holocene extinction
The Holocene extinction, otherwise referred to as the sixth mass extinction or Anthropocene extinction, is an ongoing extinction event of species during the present Holocene epoch (geology), epoch (with the more recent time sometimes called Anthr ...
, streams play an important
corridor
Corridor or The Corridor may refer to:
Arts, entertainment, and media
Films
*The Corridor (1968 film), ''The Corridor'' (1968 film), a 1968 Swedish drama film
*The Corridor (1995 film), ''The Corridor'' (1995 film), a 1995 Lithuanian drama fi ...
role in connecting
fragmented habitats and thus in conserving
biodiversity
Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

. The study of streams and
waterway
A waterway is any navigable
A body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel (e.g. boats) to pass safely. Such a navigable water is called a ''waterway'', and is preferably w ...

s in general is known as ''surface
hydrology
Hydrology (from Ancient Greek, Greek wikt:ὕδωρ, ὕδωρ, ''hýdōr'' meaning "water" and wikt:λόγος, λόγος, ''lógos'' meaning "study") is the scientific study of the movement, distribution, and management of water on Earth and ...
'' and is a core element of
environmental geography
Integrated geography (also referred to as integrative geography, environmental geography or human–environment geography) is the branch of geography
Geography (from Greek: , ''geographia'', literally "earth description") is a field of sc ...
.
Types
Brook
A stream smaller than a creek, especially one that is fed by a
spring
Spring(s) may refer to:
Common uses
* Spring (season), a season of the year
* Spring (device), a mechanical device that stores energy
* Spring (hydrology), a natural source of water
* Spring (mathematics), a geometric surface in the shape of a heli ...
or
seep
A seep or flush is a moist or wet place where water
Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent ...
. It is usually small and easily
forded. A brook is characterised by its shallowness.
Creek
A creek () or crick ():
* In Australia, Canada, New Zealand, and the United States, a (narrow) stream that is smaller than a river; a minor tributary of a river; a brook. Sometimes navigable by motor craft and may be intermittent.
* In the UK, India, and parts of
Maryland
Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware ...

,
New England
New England is a region comprising six states in the Northeastern United States
The Northeastern United States (also referred to as the American Northeast, the Northeast, and the East Coast) is a geographical region
In geography
...

, a
inlet
An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of water, body of salt water, such as a Sound (geography), sound, bay, lagoon, or marsh.
Overview
In sea coasts, ...

, typically in a
salt marsh
A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh
A tidal marsh (also known as a type of "tidal wetland") is a marsh found along rivers, coasts and estuary, estuaries which floods and drains by the tide, tidal move ...

or
mangrove swamp
A mangrove swamp is a distinct saline woodland
A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest
A forest is ...

, or between enclosed and drained former salt marshes or swamps (e.g.
Port Creek separating
Portsea Island
Portsea Island is a flat, low-lying island in area, just off the southern coast of England in the county of Hampshire, which contains the majority of the city of Portsmouth.
Portsea Island has the third-largest population of all the isla ...
from the mainland). In these cases, the "stream" is the tidal stream, the course of the
seawater
Seawater, or salt water, is water
Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for al ...

through the
creek
A creek is a stream that is usually smaller than a river
Creek may refer to:
People
* Muscogee, also known as Creek, Native Americans
* Murder of Amber Creek, Amber Creek (1982–1997), American murder victim
* Mitch Creek (born 1992), Austral ...
channel at low and high tide.
River
A large natural stream, which may be a
waterway
A waterway is any navigable
A body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel (e.g. boats) to pass safely. Such a navigable water is called a ''waterway'', and is preferably w ...

.
Runnel
The linear channel between the parallel ridges or
on a shoreline beach or river floodplain, or between a bar and the shore. Also called a
swale.
Tributary
A
tributary
A tributary, or affluent, is a stream
A stream is a body of water
(Lysefjord) in Norway
Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål
Bokmål (, ; literally "book tongue") ...
is a contributory stream, or a stream which does not reach a static body of water such as a lake or ocean, but joins another river (a parent river). Sometimes also called a branch or fork.
[Bisson, Peter and Wondzell, Steven]
"Olympic Experimental State Forest Synthesis of Riparian Research and Monitoring"
United States Forest Service
The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency in ...
, p. 15 (December 1, 2009).
Distributary
A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. Distributaries are a common feature of
river delta
A river delta is a landform
A landform is a natural or artificial feature of the solid surface of the Earth or other planetary body
A planet is an astronomical body
Astronomy (from el, ἀστρονομία, literally meaning the ...

s. The phenomenon is known as
river bifurcation
River deltas such as the pictured delta of the Salween River in Myanmar">Salween_River.html" ;"title="River deltas such as the pictured delta of the Salween River">River deltas such as the pictured delta of the Salween River in Myanmar often show ...
. Distributaries are often found where a stream approaches a
lake
A lake is an area filled with water, localized in a basin, surrounded by land
Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable ove ...

or an
ocean
The ocean (also the sea
The sea, connected as the world ocean or simply the ocean
The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth. . They can also occur inland, on
alluvial fan
An alluvial fan is an accumulation of sediments shaped like a section of a shallow cone, with its apex at a point source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to ...

s, or where a tributary stream bifurcates as it nears its
confluence
In geography
Geography (from Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece
Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ...

with a larger stream.
Common terms to name individual river distributaries in
English-speaking countries
Speakers of English
English usually refers to:
* English language
English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become the Wo ...
are ''arm'' and ''channel''.
Other names
There are a number of regional names for a stream.
Northern America
* ''Branch'' is used to name streams in Maryland and Virginia.
* ''Creek'' is common throughout the United States, as well as Australia.
* ''Falls'' is also used to name streams in Maryland, for streams/rivers which have waterfalls on them, even if such falls only have a small vertical drop.
Little Gunpowder Falls and the
Jones Falls
The Jones Falls is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map , accessed April 1, 2011 stream in Maryland
Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid- ...
are actually rivers named in this manner, unique to Maryland.
* ''
Kill
Kill often refers to:
*Homicide, one human killing another
Kill may also refer to:
Media
*''Kill!'', a 1968 film directed by Kihachi Okamoto
*Kill (Cannibal Corpse album), ''Kill'' (Cannibal Corpse album), 2006
*Kill (Electric Six album), ''Kill' ...
'' in
New York
New York most commonly refers to:
* New York City, the most populous city in the United States, located in the state of New York
* New York (state), a state in the northeastern United States
New York may also refer to:
Film and television
* New ...
,
Pennsylvania
Pennsylvania ( , elsewhere ; pdc, Pennsilfaani), officially the Commonwealth of Pennsylvania, is a landlocked
A landlocked country is a country that does not have territory connected to an ocean or whose coastlines lie on endorheic basi ...

,
Delaware
Delaware ( ) is a state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes i ...
, and
New Jersey
New Jersey is a U.S. state, state in the Mid-Atlantic States, Mid-Atlantic and Northeastern United States, Northeastern regions of the United States. It is bordered on the north and east by the state of New York (state), New York; on the ea ...
comes from a
Dutch language
Dutch ( ) is a West Germanic language spoken by about 25 million people as a first language and 5 million people as a second language, constituting most of the population of the Netherlands
)
, national_anthem = ( en, "William of ...
word meaning "riverbed" or "water channel", and can also be used for the UK meaning of 'creek'.
* ''Run'' in
Ohio
Ohio () is a state
State may refer to:
Arts, entertainment, and media Literature
* ''State Magazine'', a monthly magazine published by the U.S. Department of State
* The State (newspaper), ''The State'' (newspaper), a daily newspaper in Co ...

,
Maryland
Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware ...

,
Michigan
Michigan () is a state
State may refer to:
Arts, entertainment, and media Literature
* ''State Magazine'', a monthly magazine published by the U.S. Department of State
* The State (newspaper), ''The State'' (newspaper), a daily newspaper ...

, New Jersey, Pennsylvania, Virginia, or West Virginia can be the name of a stream.
* ''Run'' in
Florida
Florida is a U.S. state, state located in the Southeastern United States, Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia (U.S. state), Geor ...

is the name given to streams coming out of small natural
springs
Spring(s) may refer to:
Common uses
* Spring (season), a season of the year
* Spring (device), a mechanical device that stores energy
* Spring (hydrology), a natural source of water
* Spring (mathematics), a geometric surface in the shape of a heli ...
. ''River'' is used for streams from larger springs like the
Silver River and
.
* ''Stream'' and ''brook'' are used in
Midwestern states,
Mid-Atlantic states
The Middle Atlantic states, commonly shortened to Mid-Atlantic states, is a region
In geography, regions are areas that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and the ...
, and
New England
New England is a region comprising six states in the Northeastern United States
The Northeastern United States (also referred to as the American Northeast, the Northeast, and the East Coast) is a geographical region
In geography
...

.
United Kingdom
* ''Allt'' is used in the
Scottish Highlands
The Highlands ( sco, the Hielands; gd, a’ Ghàidhealtachd , 'the place of the Gaels
The Gaels ( ; ga, Na Gaeil ; gd, Na Gàidheil ; gv, Ny Gaeil ) are an ethnolinguistic group
An ethnolinguistic group (or ethno-linguistic group) ...

.
* ''
Beck
is a Japanese manga
Manga (Japanese
Japanese may refer to:
* Something from or related to Japan
, image_flag = Flag of Japan.svg
, alt_flag = Centered deep red circle on a white recta ...
'' is used in
Lincolnshire
Lincolnshire (abbreviated Lincs.) is a Counties of England, county in the East Midlands of England, with a long coastline on the North Sea to the east. It borders Norfolk to the south-east, Cambridgeshire to the south, Rutland to the south-w ...

to
Cumbria
Cumbria ( ) is a ceremonial
A ceremony (, ) is a unified ritual
A ritual is a sequence of activities involving gestures, words, actions, or objects, performed according to a set sequence. Rituals may be prescribed by the traditions of a ...

in areas which were once occupied by the Danes and Norwegians.
* ''
Bourne
Bourne or Bourn may refer to:
General Water
* A bourne (stream), an intermittent stream, flowing from a spring
* A winterbourne (stream), a stream or river that is dry through the summer months
Organizations
*Bourne Co. Music Publishers, an Ameri ...
'' or ''
winterbourne'' is used in the chalk
downland
, Isle of Wight
The Isle of Wight () is a Counties of England, ceremonial county and the List of islands of England, largest and second-most populous island in England. It is in the English Channel, between two and five miles off the coast of H ...
of southern England for ephemeral rivers. When permanent, they are ''
chalk streams''.
* ''Brook''.
* ''Burn'' is used in Scotland and
North East England
North East England is one of nine official regions of England at the First-level NUTS of the European Union, first level of NUTS statistical regions of the United Kingdom, NUTS for Eurostat, statistical purposes. The region includes the counti ...
.
* ''
Gill
A gill () is a respiratory organ that many aquatic
Aquatic means relating to water
Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent ...
'' or ''ghyll'' is seen in the north of England and
Kent
Kent is a county
A county is a geographical region of a country used for administrative or other purposesChambers Dictionary
The ''Chambers Dictionary'' (''TCD'') was first published by William Chambers (publisher), William and Robert ...

and
Surrey
Surrey () is a county
A county is a geographical region of a country used for administrative or other purposesChambers Dictionary
The ''Chambers Dictionary'' (''TCD'') was first published by William Chambers (publisher), William and R ...

influenced by
Old Norse
Old Norse, Old Nordic, or Old Scandinavian is a stage of development of North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia
Scandinavia; : ''Skades ...
. The variant "ghyll" is used in the
Lake District
The Lake District, also known as the Lakes or Lakeland, is a mountainous region in North West England. A popular holiday destination, it is famous for its lakes, forests and mountains (or ''fells''), and its associations with William Wordsworth ...

and appears to have been an invention of
William Wordsworth
William Wordsworth (7 April 177023 April 1850) was an English Romantic
Romantic may refer to:
Genres and eras
* The Romantic era, an artistic, literary, musical and intellectual movement of the 18th and 19th centuries
** Romantic music, of ...

.
* ''Nant'' is used in Wales.
* '' Rivulet'' is a term encountered in Victorian era publications.
* ''Stream''
* ''
Syke
Syke () is a town in the district of Diepholz, Lower Saxony
Lower Saxony (german: Niedersachsen ; nds, Neddersassen; stq, Läichsaksen) is a German state
The Federal Republic of Germany, as a federal state, consists of sixteen partl ...
'' is used in the
Scottish Lowlands
The Lowlands ( sco, Lallans or ; gd, a' Ghalldachd, , place of the foreigners, ) is a cultural and historical region of Scotland
Scotland ( sco, Scotland, gd, Alba
Alba (Scottish Gaelic
Scottish Gaelic ( gd, Gàidhlig or Sc ...
and Cumbria for a seasonal stream.
Other terminology
;
Bar
Bar or BAR may refer to:
Food
*Bar (establishment)
A bar is a long raised narrow table or bench designed for dispensing beer or other alcoholic beverage, alcoholic drinks. They were originally chest high, and a bar, often brass, ran the len ...
: A
shoal
In oceanography
Oceanography (from the Ancient Greek
Ancient Greek includes the forms of the used in and the from around 1500 BC to 300 BC. It is often roughly divided into the following periods: (), Dark Ages (), the peri ...
that develops in a stream as sediment is deposited as the current slows or is impeded by wave action at the confluence.
;
Bifurcation
Bifurcation or bifurcated may refer to:
Science and technology
* Bifurcation theory, the study of sudden changes in dynamical systems
** Bifurcation, of an incompressible flow, modeled by squeeze mapping#Fluid flow, squeeze mapping the fluid flow
* ...
: A fork into two or more streams.
;
Channel
Channel, channels, channeling, etc., may refer to:
Geography
* Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water.
Australia
* Channel Country, region of outback Austr ...
: A depression created by constant
erosion
In earth science
Earth science or geoscience includes all fields of natural science
Natural science is a branch of science
Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

that carries the stream's flow.
;
Confluence
In geography
Geography (from Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece
Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ...
: 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
A drainage basin is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. The drainage basin includes all the surface water from surface runoff, rain runoff, snowm ...

: (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
The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America
South America is a entirely in the and mostly in the , with a relatively small portion in the . It can also be described as the southern of a single con ...

contains many smaller drainage basins.
;
Floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows int ...
: Lands adjacent to the stream that are subject to
flood
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide
Tides are the rise and fall of sea level
Mean sea level (MSL) (often ...

ing when a stream overflows its banks.
[
]
;
Gaging station: A site along the route of a stream or river, used for reference marking or water monitoring.
;
Headwaters
The headwaters of a river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course witho ...
: 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
A point source is a single identifiable ''localised'' source of something. A point source has negligible extent, distinguishing it from other source geometries. Sources are called point sources because in mathematical modeling, these sources can us ...
.
;
Knickpoint
250px, The Horseshoe Falls, one of the three Niagara Falls. The falls are a knickpoint, formed by slower erosion above the falls than below.
In geomorphology
incised into shale at the foot of the North Caineville Plateau, Utah, within the pass ...
: The point on a stream's profile where a sudden change in
stream gradientStream gradient is the grade (slope), grade measured by the ratio of drop in elevation of a stream per unit horizontal distance, usually expressed as metre, meters per kilometre, kilometer or Foot (length), feet per mile.
Hydrology and geology
A hig ...
occurs.
;
Mouth
In animal anatomy
Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization ...

: The point at which the stream discharges, possibly via an
estuary
An estuary is a partially enclosed Coast, coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime envir ...

or
delta
Delta commonly refers to:
* Delta (letter) (Δ or δ), a letter of the Greek alphabet
* River delta, a landform at the mouth of a river
* D (NATO phonetic alphabet: "Delta"), the fourth letter of the modern English alphabet
* Delta Air Lines, an Ame ...

, into a static body of water such as a
lake
A lake is an area filled with water, localized in a basin, surrounded by land
Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable ove ...

or
ocean
The ocean (also the sea
The sea, connected as the world ocean or simply the ocean
The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth. .
;
Pool
Pool may refer to:
Water pool
* Swimming pool
A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming or other leisure activities. Pools can be ...
: A segment where the water is deeper and slower moving.
;
Rapids
Rapids are sections of a river where the river bed has a relatively steep gradient
In vector calculus, the gradient of a scalar-valued function, scalar-valued differentiable function of Function of several variables, several variables is the ...

: A
turbulent
In fluid dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases ...

, fast-flowing stretch of a stream or river.
;
Riffle
A riffle is a shallow in a flowing channel, and it has specific topographic, sedimentary, and hydraulic indicators. These are almost always assessed at a very low discharge compared to the flow that fills the channel (approximately 10–20%), ...

: A segment where the flow is shallower and more
turbulent
In fluid dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases ...

.
;
River
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

: A large natural stream, which may be a
waterway
A waterway is any navigable
A body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel (e.g. boats) to pass safely. Such a navigable water is called a ''waterway'', and is preferably w ...

.
; Run: A somewhat smoothly flowing segment of the stream.
;
Source
Source or subsource or ''variation'', may refer to:
Research
* Historical document
* Historical source
* Source (intelligence) or subsource, typically a confidential provider of non open-source intelligence
* Source (journalism), a person, public ...
: The spring from which the stream originates, or other point of origin of a stream.
;
Spring
Spring(s) may refer to:
Common uses
* Spring (season), a season of the year
* Spring (device), a mechanical device that stores energy
* Spring (hydrology), a natural source of water
* Spring (mathematics), a geometric surface in the shape of a heli ...
: The point at which a stream emerges from an underground course through unconsolidated
sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. ...

s or through caves. A stream can, especially with
cave
A cave or cavern is a natural void in the Earth#Surface, ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can also refer to much small ...

s, flow aboveground for part of its course, and underground for part of its course.
;
Stream bed
A stream bed or streambed is the channel bottom of a stream
A stream is a body of water with surface water flowing within the stream bed, bed and Bank (geography), banks of a Channel (geography), channel. The flow of a stream is controlle ...
: The bottom of a stream.
; Stream corridor: Stream, its floodplains, and the transitional upland fringe
;
Streamflow
Streamflow, or channel runoff, is the flow of water
Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main cons ...

: The water moving through a stream channel.
;
Thalweg
In geography and fluvial geomorphology, a thalweg or talweg () is the line of lowest elevation within a valley or watercourse.
Under international law, a thalweg is the middle of the primary navigable channel of a waterway that defines the boundar ...

: The river's longitudinal section, or the line joining the deepest point in the channel at each stage from source to mouth.
;
Waterfall
A waterfall is a point in a or where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where drops over the edge of a tabular or .
Waterfalls can be formed in several ways, but the most common method of fo ...

or cascade: The fall of water where the stream goes over a sudden drop called a
knickpoint
250px, The Horseshoe Falls, one of the three Niagara Falls. The falls are a knickpoint, formed by slower erosion above the falls than below.
In geomorphology
incised into shale at the foot of the North Caineville Plateau, Utah, within the pass ...
; some knickpoints are formed by erosion when water flows over an especially resistant
stratum
In geology and related fields, a stratum (plural: strata) is a layer of sedimentary rock or soil, or igneous rock that was formed at the Earth's surface, with internally consistent characteristics that distinguish it from other layers. The "str ...
, followed by one less so. The stream expends
kinetic energy
In physics
Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular ...
in "trying" to eliminate the knickpoint.
;
Wetted perimeter
Image:Wetted perimeter.gif, Change of wetted perimeter (blue) of trapezoidal canal as a function of angle ''ψ''.
The wetted perimeter is the perimeter of the cross sectional area that is "wet". The length of line of the intersection of channel wett ...

: The line on which the stream's surface meets the channel walls.
Sources

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 streams often derive most of their water from
precipitation
In meteorology
Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology dates back , though significant progress in meteorology did not begin until the 18th century. The 19th century saw mod ...
in the form of
rain
Rain is liquid water in the form of droplet
Rain water flux from a canopy. Among the forces that govern drop formation: cohesion, Van der Waals force">Cohesion_(chemistry).html" ;"title="surface tension, Cohesion (chemistry)">cohesion, ...

and
snow
Snow comprises individual ice
Ice is water
Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). ...

. Most of this precipitated water re-enters the atmosphere by
evaporation
Evaporation is a type of vaporization Vaporization (or vaporisation) of an element or compound is a phase transition from the liquid phase to vapor. There are two types of vaporization: evaporation and boiling. Evaporation is a surface phe ...

from soil and water bodies, or by the
evapotranspiration
Evapotranspiration (ET) is the sum of water evaporation and transpiration from a surface area to the Atmosphere of Earth, atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and ...

of plants. Some of the water proceeds to sink into the earth by
infiltration
Infiltration may refer to:
Science, medicine, and engineering
*Infiltration (hydrology), downward movement of water into soil
*Infiltration (HVAC), a heating, ventilation, and air conditioning term for air leakage into buildings
*Infiltration (med ...
and becomes
groundwater
Groundwater is the water
Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known form ...

, much of which eventually enters streams. Some precipitated water is temporarily locked up in snow fields and
glacier
A glacier (; ) is a persistent body of dense ice
Ice is into a state. Depending on the presence of such as particles of soil or bubbles of air, it can appear transparent or a more or less bluish-white color.
In the , ice is abunda ...

s, to be released later by evaporation or melting. The rest of the water flows off the land as
runoff
Runoff, run-off or RUNOFF may refer to:
* RUNOFF, the first computer text-formatting program
* Runoff or run-off, another name for bleed (printing), bleed, printing that lies beyond the edges to which a printed sheet is trimmed
* Runoff or run-off ...
, 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.
Characteristics
Ranking
To qualify as a stream, a body of water must be either recurring or perennial. Recurring (
intermittent
In dynamical systems, intermittency is the irregular alternation of phases of apparently periodic and Chaos theory, chaotic dynamics (Pomeau–Manneville scenario, Pomeau–Manneville dynamics), or different forms of chaotic dynamics (crisis-in ...
) 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. Thus, if a first-order stream joins a second-order stream, it remains a second-order stream. It is not until a second-order stream combines with another second-order stream that it becomes a third-order stream.
Gradient
The ''gradient'' of a stream is a critical factor in determining its character and is entirely determined by its
base level
In geology
Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and the processe ...
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.
Meander
Meander
A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediment
Sediment is a naturally occurring material that is broken down by processes of weath ...

s 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
An oxbow lake is a U-shaped lake that forms when a wide meander of a river is Meander cutoff, cut off, creating a free-standing body of water. In south Texas, oxbows left by the Rio Grande are called ''resaca (channel), resacas''. In Australia ...

'' or ''bayou''. A flood may also cause a meander to be cut through in this way.
Profile
Typically, streams are said to have a particular ''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. However, a stream may meander for some distance before falling into a "young" stream condition.
Stream load
The
stream load{{page numbers needed, date=November 2020
Stream load is a geologic term referring to the solid matter carried by a stream (Strahler and Strahler, 2006). Erosion and bed shear stress continually remove mineral material from the stream bed, bed and ...

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
The velocity of an object is the rate of change of its position with respect to a frame of reference
In physics
Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical scie ...

of the stream.
Perennial and non-perennial
Perennial streams
A ''perennial stream'' is one which flows continuously all year.
[ Water Supply Paper 494.]
Some perennial streams may only have continuous flow in segments of its stream bed year round during years of normal rainfall.
Blue-line streams are perennial streams and are marked on topographic maps with a solid blue line.
Non-perennial streams
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,
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.
According to official US definitions, the channels of intermittent streams are well-defined,
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.
An ephemeral stream does not have the biological, hydrological, and physical characteristics of a continuous or intermittent stream.
[ The same non-perennial channel might change characteristics from intermittent to ephemeral over its course.][
]
Intermittent or seasonal stream
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. These flash floods often catch travelers by surprise.
=USA
=
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. A ''Arroyo (creek), wash'' or ''desert wash'' is normally a dry streambed in the deserts of the American Southwest, which flows only after significant rainfall.
=Italy
=
In Italy, an intermittent stream is termed a torrent ( it, 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 mountains, Apennine rather than Alps, 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. However, there are also glacial torrents with a different seasonal regime.
=Other regions
=
An intermittent stream can also be called an arroyo (creek), arroyo in Latin America, a winterbourne in Britain, or a wadi in the Arabic-speaking world. In Australia, an intermittent stream is usually called a creek and marked on topographic maps with a solid blue line.
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). 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.
Crossings
Stream crossings are where streams are crossed by roads, Pipeline transport, pipelines, railways, or any other thing which might restrict the flow of the stream in ordinary or flood
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide
Tides are the rise and fall of sea level
Mean sea level (MSL) (often ...

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
* Chalk stream
* Head cut (stream geomorphology), Head cut
* Playfair's Law
* River ecosystem
* Rock-cut basin
References
External links
Glossary of stream-related terms
StreamNet
{{Authority control
Water streams,
Bodies of water
Fluvial landforms
Geomorphology
Hydrology
Rivers