Drainage system (geomorphology)
In
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 systems (from
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
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 develops on rocks that are of approximately uniform resistance to
Radial drainage pattern
In a radial drainage system, the streams radiate outwards from a central high point.
In India, the
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
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
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
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
References
- ^ a b Pidwirny, M., (2006). "The Drainage Basin Concept". Fundamentals of Physical Geography, 2nd Edition.
- ^ a b c d e "Ritter, Michael E., The Physical Environment: an Introduction to Physical Geography. 2006". Archived from the original on 2017-09-02. Retrieved 2014-07-18.
- ISBN 0-8160-3823-6.
- ISBN 978-3-030-04954-6.
- ^ "11 Water – An Introduction to Geology". Retrieved 2022-09-28.
- .
- ISBN 0-07-018780-0(this author defines dendritic, trellis, rectangular, angular, radial, annular, centripetal and parallel drainage patterns)
- ISBN 0922152349.
- ^ .
- ^ 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.
- doi:10.1130/B30458.1.
- doi:10.1130/G19607.1.