Drainage system (geomorphology)

In geomorphology, drainage systems, also known as river systems, are the patterns formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of the land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land. Geomorphologists and hydrologists often view streams as being part of drainage basins. A drainage basin is the topographic region from which a stream receives runoff, throughflow, and groundwater flow. The number, size, and shape of the drainage basins found in an area vary and the larger the topographic map, the more information on the drainage basin is available.[1]

Yarlung Tsangpo river tibet
Dendritic drainage: the Yarlung Tsangpo River, Tibet, seen from space: snow cover has melted in the valley system.

Drainage patterns

According to the configuration of the channels, drainage systems can fall into one of several categories known as drainage patterns. Drainage patterns depend on the topography and geology of the land.[2]

Accordant drainage patterns

A drainage system is described as accordant if its pattern correlates to the structure and relief of the landscape over which it flows.[2]

Dendritic Drainage pattern
Dendritic drainage patterns

Dendritic drainage pattern

Dendritic drainage systems (from Greek δενδρίτης, dendrites, "of or parallel to a tree") are not straight and are the most common form of drainage system. In a dendritic system, there are many contributing streams (analogous to the twigs of a tree), which are then joined together into the tributaries of the main river (the branches and the trunk of the tree, respectively). They develop where the river channel follows the slope of the terrain. Dendritic systems form in V-shaped valleys; as a result, the rock types must be impervious and non-porous.[3]

Parallel drainage pattern
Parallel drainage pattern

Parallel drainage pattern

A parallel drainage system is a pattern of rivers caused by steep slopes with some relief. Because of the steep slopes, the streams are swift and straight, with very few tributaries, and all flow in the same direction. This system forms on uniformly sloping surfaces, for example, rivers flowing southeast from the Aberdare Mountains in Kenya.

Parallel drainage patterns form where there is a pronounced slope to the surface. A parallel pattern also develops in regions of parallel, elongate landforms like outcropping resistant rock bands. Tributary streams tend to stretch out in a parallel-like fashion following the slope of the surface. A parallel pattern sometimes indicates the presence of a major fault that cuts across an area of steeply folded bedrock. All forms of transitions can occur between parallel, dendritic, and trellis patterns.

Trellis drainage pattern

The geometry of a trellis drainage system is similar to that of a common garden trellis along a strike valley, smaller tributaries feed into from the steep slopes on the sides of mountains. These tributaries enter the main river at approximately 90 degree angle, causing a trellis-like appearance of the drainage system. They form where hard and soft rocks exist parallel to each other. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America and in the north part of Trinidad.[2]

Rectangular
Rectangular drainage pattern

Rectangular drainage pattern

Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of joining at approximately right angles or 90 degrees. The joints are usually less resistant to erosion than the bulk rock so erosion tends to preferentially open the joints and streams eventually develop along the joints. The result is a stream system in which streams consist mainly of straight line segments with right angle bends and tributaries join larger streams at right angles.[2] This pattern can be found with the Arun River in Nepal.

Radial
Radial drainage pattern

Radial drainage pattern

In a radial drainage system, the streams radiate outwards from a central high point. Volcanos usually display excellent radial drainage. They can sometimes also be found on tops of mountains. Other geological features on which radial drainage commonly develops are domes and laccoliths. On these features the drainage may exhibit a combination of radial patterns. The radical pattern develops when streams flow in different directions from a central peak or dome like structure. In India the Amarkantak range shows the best example of radial drainage pattern.

Centripetal drainage pattern

The centripetal drainage system is similar to the radial drainage system, with the only exception is that they have streams ending into a lowland rather originating from it.

Deranged drainage pattern

A deranged drainage system is a drainage system in drainage basins where there is no coherent pattern to the rivers and lakes. It happens in areas where there has been much geological disruption. The classic example is the Canadian Shield. During the last ice age, the topsoil was scraped off, leaving mostly bare rock. The melting of the glaciers left land with many irregularities of elevation and a great deal of water to collect in the low points, explaining the large number of lakes which are found in Canada. The drainage basins are young and are still sorting themselves out. Eventually the system will stabilize.[1]

Annular
Annular drainage pattern

Annular drainage pattern

In an annular drainage pattern streams follow a roughly circular or concentric path along a belt of weak rock, resembling in plan a ringlike pattern. It is best displayed by streams draining a maturely dissected structural dome or basin where erosion has exposed rimming sedimentary strata of greatly varying degrees of hardness, as in the Red Valley, which nearly encircles the domal structure of the Black Hills of South Dakota.

Angular drainage pattern

Angular drainage patterns form where bedrock joints and faults intersect at more acute angles than rectangular drainage patterns. Angles are both more and less than 90 degrees.[4]

Discordant drainage patterns

A drainage pattern is described as discordant if it does not correlate to the topography and geology of the area. Discordant drainage patterns are classified into two main types: antecedent and superimposed,[2] while anteposition drainage patterns combine the two. In antecedent drainage, a river's vertical incision ability matches that of land uplift due to tectonic forces. Superimposed drainage develops differently: initially, a drainage system develops on a surface composed of 'younger' rocks, but due to denudative activities this surface of younger rocks is removed and the river continues to flow over a seemingly new surface, but one in fact made up of rocks of old geological formation.

See also

References

  1. ^ a b Pidwirny, M., (2006). "The Drainage Basin Concept". Fundamentals of Physical Geography, 2nd Edition.
  2. ^ a b c d e Ritter, Michael E., The Physical Environment: an Introduction to Physical Geography. 2006
  3. ^ Lambert, David (1998). The Field Guide to Geology. Checkmark Books. pp. 130–131. ISBN 0-8160-3823-6.
  4. ^ Easterbrook, Don J (1969). Chapter 7, Origins of Stream Valleys and Drainage Patterns. Principles of Geomorphology. McGraw-Hill Book Company. pp. 148-153. ISBN 0-07-018780-0 (this author defines dendritic, trellis, rectangular, angular, radial, annular, centripetal and parallel drainage patterns)

External links

Avulsion (river)

In sedimentary geology and fluvial geomorphology, avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are much less steep than the slope that the river could travel if it took a new course.

Deranged

Deranged may refer to psychosis, a generic psychiatric term for a mental state often described as involving a "loss of contact with reality".

Deranged may also refer to:

In films:

Deranged (1974 film), a 1974 American horror film

Deranged (1987 film), a 1987 Amerincan Horror B Movie film

Deranged (2012 film), a 2012 South Korean science fiction, horror and thriller film

Idaho Transfer, a 1973 American film also known under its UK video title of DerangedIn music:

Deranged (band), a Swedish death metal band formed in 1991

Deranged Records, a Canadian punk record labelIn television:

Deranged (TV series), a television series shown on the Investigation Discovery networkOther uses:

Deranged, a type of drainage system (geomorphology)

Ibrahim of the Ottoman Empire (1615–1648), Ottoman Sultan called Ibrahim the Deranged

Derangement, in combinatorial mathematics, a permutation of the elements of a set in which none of the elements appear in their original position

Drainage

Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditions that harm root growth), but many soils need artificial drainage to improve production or to manage water supplies.

Drainage system

Drainage system may refer to:

Drainage system (geomorphology), patterns formed by streams, rivers, and lakes in a drainage basin

Drainage system (agriculture), a system by which water is drained on or in the soil to enhance production

Sustainable drainage system, designed to reduce the potential impact of development

Floodplain

A floodplain or flood plain is an area of land adjacent to a stream or river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge. The soils usually consist of clays, silts, and sands deposited during floods.

Geomorphology

Geomorphology (from Ancient Greek: γῆ, gê, "earth"; μορφή, morphḗ, "form"; and λόγος, lógos, "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near the Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field.

Land drainage (disambiguation)

Land drainage may refer to:

Surface drainage of the land

Drainage system (geomorphology), pattern of natural drains, streams, rivers, etc.

Land drainage - a legal and operational term in the UK to define a range of functions and responsibilities of drainage boards.

Surface runoff, surface runoff of excess rainfall from the land

Drainage system (agriculture), land forming or land shaping to enhance the drainage from the soil surface in agricultural land

Contour plowing, controlling runoff and soil erosion

Subsurface (groundwater) drainage

Horizontal drainage by pipes and ditches

Drainage

Tile drainage

Watertable control

Vertical drainage by wells

Well drainage

Watertable control

Lilly Arbor Project

The Lilly Arbor Project is a part of an experimental riparian floodplain reforestation and ecological restoration program, located along the White River in Indiana, in the eastern United States.

Mouth bar

A mouth bar is a bar in a river that is typically created in the middle of a channel in a river delta. It is created by a positive feedback between mid-channel deposition and flow divergence. As the flow diverges near the ocean, sediment settles out in the channel and creates an incipient mouth bar. As flow is routed around the incipient bar, additional sediment is deposited on the incipient bar. This continued process results in the formation of a full-fledged mouth bar, which causes the channel to bifurcate. This continued process leads to the characteristic fractal tree pattern found in some prograding river-dominated deltas.

Oxbow lake

An oxbow lake is a U-shaped lake that forms when a wide meander of a river is cut off, creating a free-standing body of water. This landform is so named for its distinctive curved shape, which resembles the bow pin of an oxbow. In Australia, an oxbow lake is called a billabong, from the indigenous Wiradjuri language. In south Texas, oxbows left by the Rio Grande are called resacas.

The word "oxbow" can also refer to a U-shaped bend in a river or stream, whether or not it is cut off from the main stream.

Stream pool

A stream pool, in hydrology, is a stretch of a river or stream in which the water depth is above average and the water velocity is below average.

Large-scale features
Alluvial rivers
Bedrock river
Bedforms
Regional processes
Mechanics

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