Sheet erosion

Sheet erosion or sheet wash is the even erosion of substrate along a wide area.[1] Sheet erosion occur in wide range of settings such as coastal plains, hillslopes, floodplains and beaches.[2] Water moving fairly uniformly with a similar thickness over a surface is called sheet flow and is the cause of sheet erosion.[2] Sheet erosion imply that any flow of water that causes the erosion is not canalized.[2] If a hillsplope surface contains many irregularities sheet erosion may give way to erosion along small channels called rills which can converge forming gullies.[2][3] However, sheet erosion may occur despite some limited unevenness in the sheet flow arising from clods of earth, rock fragments, or vegetation.[2]

Sheet erosion occurs in two steps; first rainsplash dislodges small particles of the substrate and then the particles are carried away, usually short distances, by a thin and uniform layer of water known as sheetflow.[3] Transport by the sheetflow is usually small distances meaning sheet erosion is a low magnitude process.[3][4] However the frequency in time with which the occur may be high, compensating for the small change observed in each individual episode of sheet erosion.[4] A sheetflood can be distinguished from ordinary an sheetflow by its much greater magnitude and much lesser frequency.[4] Sheetfloods have been associated by various scientists to: high-intesity rain, low relief, lack of vegetation, low permeability of the substrate, strong weather contrast between seasons, slope form and climate change. Sheetfloods are commonly tubulent while sheetflow may be laminar or turbulent.[4]

Sheet erosion is common in recently plowed fields and bare ground where the substrate, typically soil, is not consolidated.[3] The resulting loss of material by sheet erosion may result in the destruction of valuable topsoils.[3] Tough grass hinders the development of sheet flow.[5] The sheet erosion caused by a single rainstorm may account for the loss of up to hundred ton of small particles in an acre.[3]

It has been argued that in the late Neoproterozoic Era sheet erosion was a dominant erosion process due to the lack of plants on land.[6]

See also

References

  1. ↑ "Definition of SHEET EROSION". Merriam-Webster. Retrieved 23 May 2018.
  2. 1 2 3 4 5 Govers, Gerard (2004). "Sheet erosion, sheet flow, sheet wash". In Goudie, A.S. Encyclopedia of Geomorphology. Routledge. pp. 947–949.
  3. 1 2 3 4 5 6 "Sheet erosion – Britannica Online Encyclopedia". Britannica.com. Retrieved 26 September 2018.
  4. 1 2 3 4 Hogg, Susan E. (1982). "Sheetflood, sheetwash, sheetflow, or ... ?". Earth-Science Reviews. 18 (1): 59–76.
  5. ↑ Pitty, A.F. (1971). Introduction to Geomorphology. London: Methuen. p. 526.
  6. ↑ Lidmar-Bergström, Karna (1993). "Denudation surfaces and tectonics in the southernmost part of the Baltic Shield". Precambrian Research. 64: 337–345.
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