Channel (geography)

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Vivari Channel in Albania links Lake Butrint with the Straits of Corfu
.

In physical geography and hydrology, a channel is a landform on which a relatively narrow body of water is situated, such as a river, river delta or strait. While channel typically refers to a natural formation, the cognate term canal denotes a similar artificial structure.

Channels are important for the functionality of ports and other bodies of water used for navigability for shipping. Naturally, channels will change their depth and capacity due to erosion and deposition processes. Humans maintain navigable channels by dredging and other engineering processes.

By extension, the term also applies to fluids other than water, e.g., lava channels. The term is also traditionally used to describe the

waterless surface features on Venus
.

Formation

Channel initiation refers to the site on a mountain slope where water begins to flow between identifiable banks.

landslides.[1]

Overland flow is a primary factor in channel initiation where saturation overland flow deepens to increase shear stress and begin channel incision.[1] Overland flows converge in topographical depressions where channel initiation begins. Soil composition, vegetation, precipitation, and topography dictate the amount and rate of overland flow. The composition of a soil determines how quickly saturation occurs and cohesive strength retards the entrainment of material from overland flows.[1] Vegetation slows infiltration rates during precipitation events and plant roots anchor soil on hillslopes.[1]

Subsurface flow destabilizes soil and resurfaces on hillslopes where channel heads are often formed. This often results in abrupt channel heads and landslides. Hollows form due to concentrated subsurface flows where concentrations of colluvium are in a constant flux.[1] Channel heads associated with hollows in steep terrain frequently migrate up and down hillslopes depending on sediment supply and precipitation.

Natural channels

Natural channels are formed by

Columbia river
.

A stream channel is the physical confine of a

stream banks
. Stream channels exist in a variety of geometries. Stream channel development is controlled by both
drainage area
.

Examples of rivers that are trapped in their channels: Grand Canyon and Black Canyon of the Gunnison.

In a larger nautical context, as a geographical place name, the term channel is another word for

nautical context, the terms strait, channel, sound, and passage are synonymous and usually interchangeable. For example, in an archipelago, the water between islands is typically called a channel or passage. The English Channel
is the strait between England and France.

Waterflow channels

The channel form is described in terms of geometry (plan, cross-sections, profile) enclosed by the materials of its bed and banks. This form is under influence of two major forces: water discharge and sediment supply. For erodible channels the mutual dependence of its parameters may be qualitatively described by Lane's Principle (also known as Lane's relationship):[2] the product of the sediment load and bed Bukhara size is proportional to the product of discharge and channel slope.[3]

Nautical channels

See also:
Navigation canal, and Fairway (navigation)
Wooden pilings mark the navigable channel for vessels entering Lake George from the St. Johns River in Florida.

A term "navigable channel" is used as a

Panama canal providing an example.[6]

The term not only includes the

ship-navigable parts of an estuary or river leading to port facilities, but also to lesser channels accessing boat port-facilities such as marinas. When dredged channels traverse bay mud or sandy bottoms, repeated dredging is often necessary because of the unstable subsequent movement of benthic soils.[7]

Responsibility for monitoring navigability conditions of navigation channels to various port facilities varies, and the actual maintenance work is frequently performed by a third party. Storms, sea-states, flooding, and seasonal sedimentation adversely affect

Saint Louis hundreds of miles from any coast. The various state or local governments maintain lesser channels, for example former Erie Canal
.

See also

References

  1. ^ a b c d e f g h i Bierman, R. B, David R. Montgomery (2014). Key Concepts in Geomorphology. W. H. Freeman and Company Publishers. United States.
  2. ^ Lane, E.W. "The importance of fluvial morphology in hydraulic engineering", Proc. American Society of Civil Engineers, 1955, vol. 81, paper 745, pp. 533–551.
  3. ISBN 9780784476628. Archived
    from the original on 24 June 2016. Retrieved 26 November 2015.
  4. ^ a b Thoresen 2003, p. 78.
  5. ^ Fahmy & Hekal 2023, p. 33.
  6. ^ Thoresen 2003, p. 79.
  7. USACE
    , January 1983

Sources

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