Water level, also known as gauge height or stage, is the elevation of the
free surface
In physics, a free surface is the surface of a fluid that is subject to zero parallel shear stress,
such as the interface between two homogeneous fluids.
An example of two such homogeneous fluids would be a body of water (liquid) and the air in ...
of a
sea
A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...
,
stream
A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...
,
lake
A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...
or
reservoir
A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation.
Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
relative to a specified
vertical datum.
Over long distances, neglecting external forcings (such as wind), water level tends to conform to an
equigeopotential surface.
Merriam Webster Dictionary Definition of level (Entry 3 of 3): conforming to the curvature of the liquid parts of the earth's surface
/ref>
See also
* Water level (device), device utilizing the surface of liquid water to establish a local horizontal plane of reference
* Flood stage
* Hydraulic head
Hydraulic head or piezometric head is a measurement related to liquid pressure (normalized by specific weight) and the liquid elevation above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22, eq.3.2a.
It is usually meas ...
* Stream gauge
** Water level gauges
* Tide gauge
A tide gauge is a device for measuring the change in sea level relative to a vertical datum. It is also known as a mareograph, marigraph, and sea-level recorder.
When applied to freshwater continental water body, water bodies, the instrument may ...
* Level sensor
* Liquid level
* Reference water level
* Stage (hydrology)
* Sea level
Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...
References
Hydrology
Vertical position
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