is a flowing body of water
with a current
confined within a bed
and stream banks
. Depending on its locale or certain
characteristics, a stream may be referred to as a
, river syke
. In some countries or communities a stream may
be defined by its size. In the United States a stream is classified as a watercourse less than
60 feet (18 metres) wide.
Streams are important as conduits
in the water cycle
, instruments in
, and they
serve as corridors for fish
migration. The biological habitat
in the immediate vicinity of a stream is
called a riparian
. Given the status of the ongoing Holocene extinction event
play an important corridor
connecting fragmented habitat
and thus in conserving biodiversity
Stream is an umbrella term used in the scientific community for all
flowing natural waters, regardless of size. The study of streams
and waterways in general is known as surface hydrology
and is a core element of environmental geography
Creek at the Uluguru Mountains which
forms the Ruvu river
- River: A large natural stream, which may
be a waterway.
- *In North America and Australia, a small to medium sized
natural stream. Sometimes navigable by motor craft and may be
parts of New
England, the UK and India, a tidal
inlet, typically in a salt marsh or mangrove
swamp, or between enclosed and drained former salt marshes or
swamps (e.g. Port Creek separating Portsea Island from the mainland). In these cases, the
stream is the tidal stream, the course of the seawater through the creek channel at low and high tide.
- Tributary: A contributory stream, or a
stream which does not reach the sea but joins another river (a
parent river). Sometimes also called a branch or fork.
- Brook: 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 characterized by its
shallowness and its bed being composed
primarily of rocks.
Kingdom, there are several regional names for a
In North America
- Bourn in Cascadia refers
mostly to wide but relatively short, stilly streams with broad,
rocky and gravelly beaches/banks, uneven bottoms very deep in some
places but dappled with small, rocky aights, with uncommonly clear
water except for adjacent pools filled with debris and plant life
in which fishes and amphibians spawn. Often a distributary of a river and a tributary of a
coastal or lakeside marsh, or, somewhat less frequently, an
"independent" (not especially near a lake or ocean) swamp or other
- Kill in New York, Pennsylvania, Delaware, and New
Jersey comes from a Dutch
language word meaning "riverbed" or "water channel", and can
also be used for the "UK" meaning of 'creek'.
- Run in Ohio, Pennsylvania, Maryland, or Virginia can be the name of a stream.
- Branch, fork, or prong can refer to
tributaries or distributaries that share the same name as the main
stream, generally with the addition of a cardinal direction.
- Branch is also used to name streams
in Maryland and Virginia.
Parts of a stream
- Spring: 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.
- Source: The spring from
which the stream originates, or other point of origin of a
- Headwaters: 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
- Confluence: The point at
which the two streams merge. If the two tributaries are of
approximately equal size, the confluence may be called a fork.
- Run: A somewhat smoothly flowing segment of the stream.
- Pool: A segment where the water is
deeper and slower moving.
- Riffle: A segment where the flow is
shallower and more turbulent.
- Channel: A depression
created by constant erosion that carries the
- Floodplain: Lands adjacent to the
stream that are subject to flooding when a
stream overflows its banks.
- Stream bed: The bottom of a
- Gauging station: A point of
demarkation along the route of a stream or river, used for
reference marking or water monitoring.
- Thalweg: The river's longitudinal
section, or the line joining the deepest point in the channel at
each stage from source to mouth.
- Wetted perimeter: The line on
which the stream's surface meets the channel walls.
- Nickpoint: The point on a stream's
profile where a sudden change in stream
- Waterfall or cascade: The fall of water where the stream goes
over a sudden drop called a nickpoint; some nickpoints 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 nickpoint.
- Mouth: 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.
Streams typically derive most of their water from precipitation
in the form of
. Most of this
water re-enters the atmosphere by evaporation
from soil and water bodies, or by
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
, 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.
- To qualify as a stream it must be either recurring or
perennial. Recurring 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 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.
- 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 geologic 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
- 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.
- Typically, streams are said to have a particular
profile, beginning with steep gradients, no flood plain,
and little shifting of channel,
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.
Intermittent and ephemeral streams
States, an intermittent stream is one that only
flows for part of the year and is marked on topographic maps with a line of blue dashes
or desert wash
normally a dry streambed in the deserts
the American Southwest
flows only after significant rainfall. Washes can fill up quickly
during rains, and there may be a sudden torrent of water after a
begins upstream, such as
conditions. These flash floods
often catch travelers by surprise.
An intermittent stream can also be called an arroyo
, a winterbourne
Britain, or a wadi
in the Arabic
Italy an intermittent stream is termed a
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
In this case the maximum discharge will be
during the spring and autumn. However there are also glacial
torrents with a different seasonal regime.
stream is one which flows for most or all of
the year and is marked on topographic maps with a solid blue line.
, an intermittent stream is
usually called a creek and marked on topographic maps with a solid
Generally, streams that flow only during and immediately after
precipitation are termed ephemeral
. There is no clear
demarkation between surface runoff and ephemeral stream.
The extent of land basin drained by a stream is termed its
known in North America as the watershed
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
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.
this vein, a component of the Mississippi River basin is the
basin, which in turn includes
the Kentucky River
basin, and so