A reach is a segment of a stream, river, or
arm
In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between ...
of the sea, usually suggesting a straight, level, uninterrupted stretch.
They are traditionally defined by the
capabilities of sailing boats, as a stretch of a watercourse which, because it is straightish, can be sailed in one "
reach" (that is, without
tacking).
Reaches are often named by those using the river, and a reach may be named for landmarks, natural features, and historical reasons (see, for instance,
Gallions' Reach, named after the family that once owned its banks).
A reach may be an expanse, or widening, of a stream or river channel. This commonly occurs after the river or stream is dammed. A reach is similar to an
arm
In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between ...
, though an arm may bend and thus have multiple reaches. The term "reach" can also refer to a level stretch, as between river rapids or locks in a
canal
Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface ...
. The word may also be used more generally to refer to any extended portion or stretch of land or water, or even metaphorically.
In
fluvial
A river is a natural stream of fresh water that flows on land or inside 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 its course if it ru ...
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 reach is a convenient subdivision of study; it may be any length of river of fairly uniform characteristics, or the length between
gauging station
A stream gauge, streamgage or stream gauging station is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. Hydrometric measurements of water level surface elevation ("stage") and/or vo ...
s, or simply the length of a watercourse between any two defined points. These may be measured in terms of
river mile
A river mile is a measure of distance in miles along a river from its river mouth, mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometre, kilometers is the river kilometer. They are an ...
s.
As of 2015, the
US Board on Geographic Names
The United States Board on Geographic Names (BGN) is a federal body operating under the United States Secretary of the Interior. The purpose of the board is to establish and maintain uniform usage of geographic names throughout the federal gover ...
records 334 place names in the US with the characterization of a named "reach".
USGS Survey GNIS Database
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Gallery
Image:Hanford Reach.jpg, Example: Hanford Reach National Monument
The Hanford Reach National Monument is a national monument in the U.S. state of Washington. It was created in 2000, mostly from the former security buffer surrounding the Hanford Nuclear Reservation. The area has been untouched by development o ...
, Washington State, US. The last significant free-running (undammed) section of the Columbia River in the US
File:River Thames Reaches.jpg, A map of the reaches of the River Thames; it can be seen that a reach is a straightish stretch (and can therefore be sailed in one reach, one straight-line path between tacks, unless the wind is too close to head-on to allow the sailing-boat to reach)
File:Barge Match (Thames River) RMG PY4069.tiff, Thames barge
A Thames sailing barge is a type of commercial sailing boat once common on the River Thames in London. The flat-bottomed barges, with a shallow draught and leeboards, were perfectly adapted to the Thames Estuary, with its shallow waters and nar ...
s reaching on the Thames during a race; they are probably on Gravesend Reach
See also
*Meander
A meander is one of a series of regular sinuous curves in the Channel (geography), channel of a river or other watercourse. It is produced as a watercourse erosion, erodes the sediments of an outer, concave bank (cut bank, cut bank or river cl ...
*Rapid
Rapid(s) or RAPID may refer to:
Hydrological features
* Rapids, sections of a river with turbulent water flow
* Rapid Creek (Iowa River tributary), Iowa, United States
* Rapid Creek (South Dakota), United States, namesake of Rapid City
Sport ...
*Stream pool
In hydrology, a stream pool is a stretch of a river or stream in which the water depth is above average and the water velocity is below average.
Formation
A stream pool may be bedded with sediment or armoured with gravel, and in some cases t ...
References
{{DEFAULTSORT:Reach (Geography)
Physical geography
Fluvial landforms
Rivers
Water streams
Hydrology