In
hydrology
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...
, a current in a
water body is the flow of
water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
in any one particular direction. The current varies
spatially as well as
temporally, dependent upon the flow
volume
Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...
of water,
stream gradient
Stream gradient (or stream slope) is the grade (or slope) of a stream. It is measured by the ratio of drop in elevation and horizontal distance. It is a dimensionless quantity, usually expressed in units of meters per kilometer (m/km) or feet pe ...
, and
channel geometry. In
tidal zones, the current and streams may reverse on the flood tide before resuming on the
ebb tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravity, gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide ...
. On a global scale, wind and the rotation of the earth greatly influence the flow of
ocean currents
An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours ...
.
In a stream or river there the current is influenced by gravity, the term ''upstream'' (or ''upriver'') refers to the direction towards the source of the stream (or
river
A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...
), i.e. against the direction of flow. Likewise, the term ''downstream'' or ''downriver'' describes the direction towards the mouth of the stream or river, in which the current flows. The term "
left bank
In geography, a bank is the land alongside a body of water.
Different structures are referred to as ''banks'' in different fields of geography.
In limnology (the study of inland waters), a stream bank or river bank is the terrain alongsid ...
" and "
right bank
In geography, a bank is the land alongside a body of water.
Different structures are referred to as ''banks'' in different fields of geography.
In limnology (the study of inland waters), a stream bank or river bank is the terrain alongsid ...
" refers to
banks as seen from the direction of flow, towards the downstream direction.
See also
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References
Coastal geography
Hydrology
Rivers
Water streams
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