Drainage system (geomorphology)

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

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 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 part of drainage basins (and sub-basins). This is the topographic region from which a stream receives runoff, throughflow, and its saturated equivalent, groundwater flow. The number, size, and shape of the drainage basins varies and the larger and more detailed the topographic map, the more information is available. [1]

Contents

Drainage patterns

Per the lie of channels, drainage systems can fall into one of several categories, known as drainage patterns. These depend on the topography and geology of the land. [2]

All forms of transitions can occur between parallel, dendritic, and trellis patterns.

Accordant versus discordant 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]

A discordant system or pattern 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 ante position 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 denudation 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.

Dendritic drainage pattern

Dendritic drainage patterns Dendritic Drainage pattern.jpg
Dendritic drainage patterns

Dendritic drainage systems (from Greek δενδρίτης, dendrites, "of or like a tree") are not straight and are the most common form of the drainage system. In this, there are many sub-tributaries (analogous to the twigs of a tree), which merge into tributaries of the main river (the branches and the trunk of the tree, respectively). They are seen to feed a river channel that matches and is strongly accordant to the overriding gradient of the land. Truly 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.jpg
Parallel drainage pattern

A parallel drainage system occurs on elongate landforms like outcropping resistant rock bands), typically following natural faults or erosion (such as prevailing wind scars). The watercourses run swift and straight, with very few tributaries, and all flow in the same direction. This system forms on very long, uniform slopes, for instance, high rivers flowing southeast from the Aberdare Mountains in Kenya and many rivers of Myanmar.

This sometimes indicates a major fault that cuts across an area of steeply folded bedrock.

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 the steep slopes of mountainsides. These tributaries enter the main river about perpendicular, causing a trellis-like appearance of the system. They form where hard and soft formations exist on both banks of the main river, and are reflective of height, accentuated by erosion. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America and in the north part of Trinidad. [2]

Rectangular drainage pattern

Rectangular drainage pattern Rectangular.png
Rectangular drainage pattern

Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of jointing 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 drainage pattern

Radial drainage pattern Radial.png
Radial drainage pattern
The radial drainage network of Dogu'a Tembien in Ethiopia DT drainage.jpg
The radial drainage network of Dogu’a Tembien in Ethiopia

In a radial drainage system, the streams radiate outwards from a central high point. Volcanos usually have archetypal features on which this commonly develops are modest or hard domes pattern develops when streams flow in many general directions (meaning quite long-term)

In India, the Amarkantak range and Ramgarh crater are most archetypal; and Dogu'a Tembien in Ethiopia. [4]

Centripetal drainage pattern

When the streams converge at a point, which is generally a depression or a basin they form centripetal or inland drainage pattern.

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. These can form in areas with extensive limestone deposits, where surface streams can disappear into the groundwater via caves and subterranean drainage routes. [5] They can also form in areas where there has been much geological disruption.

A 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 drainage pattern

Annular drainage pattern Annular.png
Annular drainage pattern

In an annular drainage pattern, streams trace a tangential or greater concentric path along a belt of weak rock so, with others, a roughly traced out ring can be seen. 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.

Astroblemes and mud diapirs are also thought to be able to cause this kind of drainage pattern. [6]

Angular drainage pattern

Angular drainage patterns form where bedrock joints and faults intersect at angles other than rectangular drainage patterns. Angles can be more or less than 90 degrees. [7]

Integrated drainage

An integrated drainage is a mature drainage system characteristic of arid climates. It is formed by coalescing of individual basins formerly separated by high ground, such as mountains or ridges. Headward erosion from a lower basin may breach the barrier, as may spilling over from a higher basin due to aggradation (accumulation of sediments in the basin). The effect of integration of a drainage system is to replace local higher base levels with a single lower base level. [8]

An example of an integrated drainage is the area drained by the Rio Grande River. The sedimentary basins forming the modern Rio Grande Valley were not integrated into a single river system draining into the Gulf of Mexico until relatively recent geologic time. Instead, the basins formed by the opening of the Rio Grande rift were initially bolsons, with no external drainage and a central playa. [9] An axial river existed in the Espanola Basin as early as 13 million years ago, reaching the Santo Domingo Basin by 6.9 million years ago. However, at this time, the river drained into a playa in the southern Albuquerque Basin where it deposited the Popotosa Formation. [10] The upper reach of this river corresponded to the modern Rio Chama, but by 5 million years ago, an ancestral Rio Grande draining the eastern San Juan Mountains had joined the ancestral Rio Chama. [9]

The ancestral Rio Grande progressively integrated basins to the south, reaching the Palomas basin by 4.5 million years ago, the Mesilla basin by 3.1 million years, to Texas by 2.06 million years, and finally joining the Pecos River at 800,000 years to drain into the Gulf of Mexico. Volcanism in the Taos Plateau reduced drainage from the San Luis basin until a spillover event 440,000 years ago that drained Lake Alamosa and fully reintegrated the San Luis basin into the Rio Grande basin. [9]

Integrated drainages were widespread in western North America in the Paleocene and Eocene, [11] and there is evidence of integrated drainages on the surface of Mars. [12]

See also

Related Research Articles

<span class="mw-page-title-main">Valley</span> Low area between hills, often with a river running through it

A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas.

<span class="mw-page-title-main">Rio Grande</span> Major river forming part of the US–Mexico border

The Rio Grande in the United States or the Río Bravo in Mexico is one of the principal rivers in the southwestern United States and in northern Mexico. The length of the Rio Grande is 1,896 miles (3,051 km), making it the 4th longest river in the United States and in North America by main stem. It originates in south-central Colorado, in the United States, and flows to the Gulf of Mexico. The Rio Grande drainage basin (watershed) has an area of 182,200 square miles (472,000 km2); however, the endorheic basins that are adjacent to and within the greater drainage basin of the Rio Grande increase the total drainage-basin area to 336,000 square miles (870,000 km2).

<span class="mw-page-title-main">Geomorphology</span> Scientific study of landforms

Geomorphology is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain 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.

<span class="mw-page-title-main">Drainage basin</span> Land area where water converges to a common outlet

A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the drainage divide, made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern.

<span class="mw-page-title-main">Endorheic basin</span> Closed drainage basin that allows no outflow

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<span class="mw-page-title-main">Stream capture</span> Geomorphological phenomenon

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<span class="mw-page-title-main">Groundwater sapping</span>

Groundwater sapping is a geomorphic erosion process that results in the headward migration of channels in response to near constant fluid discharge at a fixed point. The consistent flow of water displaces fine sediments which physically and chemically weathers rocks. Valleys that appear to have been created by groundwater sapping occur throughout the world in areas such as England, Colorado, Hawai’i, New Zealand, and many other places. However, it is difficult to characterize a landform as being formed exclusively by groundwater sapping due to phenomena such as pluvial runoff, plunge-pool undercutting, changes in water table level, and inconsistent groundwater flow. An example of drainage ways created purely by the outflow of subsurface fluids can be seen on the foreshores of beaches. As the surge of water and sand brought to land by a wave retreats seaward, the film of water becomes thinner until it forms rhomboid shaped patterns in the sand. Small fans form at the apex of the rhombic features, which are eventually fed by the remaining backflow of water traveling downslope. Channels begin to form headward in the form of millimeter wide rills along the sides of the fans; the creation of these small channel networks culminates when the last of the backwash dissipates.

<span class="mw-page-title-main">Headward erosion</span> The Geographical processes of the Earth

Headward erosion is erosion at the origin of a stream channel, which causes the origin to move back away from the direction of the stream flow, lengthening the stream channel. It can also refer to the widening of a canyon by erosion along its very top edge, when sheets of water first enter the canyon from a more roughly planar surface above it, such as at Canyonlands National Park in Utah. When sheets of water on a roughly planar surface first enter a depression in it, this erodes the top edge of the depression. The stream is forced to grow longer at the very top of the stream, which moves its origin back, or causes the canyon formed by the stream to grow wider as the process repeats. Widening of the canyon by erosion inside the canyon, below the canyon side top edge, or origin or the stream, such as erosion caused by the streamflow inside it, is not called headward erosion.

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<span class="mw-page-title-main">Perennial stream</span> Type of river

A perennial stream is a stream that has continuous flow of surface water throughout the year in at least parts of its catchment during seasons of normal rainfall, as opposed to one whose flow is intermittent. In the absence of irregular, prolonged or extreme drought, a perennial stream is a watercourse, or segment, element or emerging body of water which continually delivers groundwater. For example, an artificial disruption of stream, variability in flow or stream selection associated with the activity in hydropower installations, do not affect this status. Perennial streams do not include stagnant water, reservoirs, cutoff lakes and ponds that persist throughout the year. All other streams, or parts of them, should be considered seasonal rivers or lakes. The stream can cycle from intermittent to perpetual through multiple iterations.

<span class="mw-page-title-main">Stream</span> Body of surface water flowing down a channel

A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks.

<span class="mw-page-title-main">River</span> Natural flowing watercourse

A river is a natural flowing watercourse, usually a freshwater stream, flowing on the Earth's land surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities, a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and Northeast England, and "beck" in Northern England. Sometimes a river is defined as being larger than a creek, but not always; the language is vague.

Channel patterns are found in rivers, streams, and other bodies of water that transport water from one place to another. Systems of branching river channels dissect most of the sub-aerial landscape, each in a valley proportioned to its size. Whether formed by chance or necessity, by headward erosion or downslope convergence, whether inherited or newly formed. Depending on different geological factors such as weathering, erosion, depositional environment, and sediment type, different types of channel patterns can form.

An antecedent stream is a stream that maintains its original course and pattern despite the changes in underlying rock topography. A stream with a dendritic drainage pattern, for example, can be subject to slow tectonic uplift. However, as the uplift occurs, the stream erodes through the rising ridge to form a steep-walled gorge. The stream thus keeps its dendritic pattern even though it flows over a landscape that will normally produce a trellis drainage pattern.

<span class="mw-page-title-main">Caballo Mountains</span>

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<span class="mw-page-title-main">Peace Vallis</span> Martian valley

Peace Vallis is an ancient stream valley on the northern rim of Gale Crater on the planet Mars. It is notable for its associated alluvial fan which lies near the Mars Science Laboratory Curiosity landing site. The valley and alluvial fan provide evidence for geologically recent (Amazonian-aged) fluvial activity and sustained water flow on Mars. Recent high-resolution orbital images of Peace Vallis and its watershed also suggest that at least one glacial episode affected Gale crater. All of this evidence has implications for the history of water on Mars and the planet's long-term habitability. Understanding Peace Vallis and its fan also provides geologic context for the rocks observed on the ground by the Curiosity rover.

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<span class="mw-page-title-main">Lake Alamosa</span> Former lake in Colorado, United States

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References

  1. 1 2 Pidwirny, M., (2006). "The Drainage Basin Concept". Fundamentals of Physical Geography, 2nd Edition.
  2. 1 2 3 4 5 "Ritter, Michael E., The Physical Environment: an Introduction to Physical Geography. 2006". Archived from the original on 2017-09-02. Retrieved 2014-07-18.
  3. ↑ Lambert, David (1998). The Field Guide to Geology. Checkmark Books. pp.  130–131. ISBN   0-8160-3823-6.
  4. ↑ Amanuel Zenebe, and colleagues (2019). The Giba, Tanqwa and Tsaliet rivers in the headwaters of the Tekezze basin. In: Geo-trekking in Ethiopia's Tropical Mountains - The Dogu'a Tembien District. SpringerNature. doi:10.1007/978-3-030-04955-3_14. ISBN   978-3-030-04954-6.
  5. ↑ "11 Water – An Introduction to Geology" . Retrieved 2022-09-28.
  6. ↑ Colucci, Sabrina; Fidani, Cristiano. "Preliminary geomorphological and hydrographical characterization of a circular structure in the Marche Region (Central Italy) and its possible origin". Géomorphologie . doi:10.4000/geomorphologie.17007.
  7. ↑ 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)
  8. ↑ Jackson, Julia A., ed. (1997). "Integrated drainage". Glossary of geology (Fourth ed.). Alexandria, Virginia: American Geological Institute. ISBN   0922152349.
  9. 1 2 3 Repasch, Marisa; Karlstrom, Karl; Heizler, Matt; Pecha, Mark (May 2017). "Birth and evolution of the Rio Grande fluvial system in the past 8 Ma: Progressive downward integration and the influence of tectonics, volcanism, and climate". Earth-Science Reviews. 168: 113–164. Bibcode:2017ESRv..168..113R. doi:10.1016/j.earscirev.2017.03.003.
  10. ↑ Koning, Daniel J.; Jochems, Andy P.; Heizler, Matthew T. (2018). "Early Pliocene paleovalley incision during early Rio Grande evolution in southern New Mesico" (PDF). New Mexico Geological Society Field Conference Series. 69: 93–108. Retrieved 20 May 2020.
  11. ↑ Mackey, G. N.; Horton, B. K.; Milliken, K. L. (2012-05-01). "Provenance of the Paleocene-Eocene Wilcox Group, western Gulf of Mexico basin: Evidence for integrated drainage of the southern Laramide Rocky Mountains and Cordilleran arc". Geological Society of America Bulletin. 124 (5–6): 1007–1024. Bibcode:2012GSAB..124.1007M. doi:10.1130/B30458.1.
  12. ↑ Hynek, Brian M.; Phillips, Roger J. (2003). "New data reveal mature, integrated drainage systems on Mars indicative of past precipitation". Geology. 31 (9): 757. Bibcode:2003Geo....31..757H. doi:10.1130/G19607.1.
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