River delta

Lena river delta
Satellite image of the Amazon Delta captured by NASA in 2005.
NASA satellite photograph of the Nile Delta (shown in false color)

A river delta is a landform shaped like a triangle, created by the deposition of sediment that is carried by a river and enters slower-moving or stagnant water.[1][2] This occurs at a river mouth, when it enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment. It is so named because its triangle shape resembles the uppercase Greek letter delta, Δ. The size and shape of a delta are controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment.[3][4] The size, geometry, and location of the receiving basin also plays an important role in delta evolution.

River deltas are important in human civilization, as they are major agricultural production centers and population centers.[5] They can provide coastline defense and can impact drinking water supply.[6] They are also ecologically important, with different species' assemblages depending on their landscape position. On geologic timescales, they are also important carbon sinks.[7]

  1. ^ Miall, A. D. 1979. Deltas. in R. G. Walker (ed) Facies Models. Geological Association of Canada, Hamilton, Ontario.
  2. ^ Elliot, T. 1986. Deltas. in H. G. Reading (ed.). Sedimentary environments and facies. Backwell Scientific Publications, Oxford.
  3. ^ Blum, M.D.; Törnqvist, T.E. (2000). "Fluvial responses to climate and sea-level change: a review and look forward". Sedimentology. 47: 2–48. doi:10.1046/j.1365-3091.2000.00008.x. S2CID 140714394.
  4. ^ Pasternack, Gregory B.; Brush, Grace S.; Hilgartner, William B. (2001-04-01). "Impact of historic land-use change on sediment delivery to a Chesapeake Bay subestuarine delta". Earth Surface Processes and Landforms. 26 (4): 409–427. Bibcode:2001ESPL...26..409P. doi:10.1002/esp.189. ISSN 1096-9837. S2CID 129080402.
  5. ^ Schneider, Pia; Asch, Folkard (2020). "Rice production and food security in Asian Mega deltas—A review on characteristics, vulnerabilities and agricultural adaptation options to cope with climate change". Journal of Agronomy and Crop Science. 206 (4): 491–503. doi:10.1111/jac.12415. ISSN 1439-037X.
  6. ^ Anthony, Edward J. (2015-03-01). "Wave influence in the construction, shaping and destruction of river deltas: A review". Marine Geology. 361: 53–78. Bibcode:2015MGeol.361...53A. doi:10.1016/j.margeo.2014.12.004.
  7. ^ Hage, Sophie; Romans, Brian W.; Peploe, Thomas G. E.; Poyatos-Moré, Miquel; Haeri Ardakani, Omid; Bell, Daniel; Englert, Rebecca G.; Kaempfe-Droguett, Sebastian A.; Nesbit, Paul R.; Sherstan, Georgia; Synnott, Dane P.; Hubbard, Stephen M. (24 October 2022). "High rates of organic carbon burial in submarine deltas maintained on geological timescales". Nature Geoscience. 15 (1): 919–924. Bibcode:2022NatGe..15..919H. doi:10.1038/s41561-022-01048-4. S2CID 253145418. Retrieved 19 April 2023.

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