A small, inceptive, river island at Sihoť, Bratislava, Slovakia
Satellite picture of Csepel Island in Hungary which is south of Budapest city centre

A river island is any exposed landmass surrounded by river water. Properly defined, it excludes shoals between seasonally varying flows and may exclude semi-coastal islands in river deltas such as Marajó.

These islands result from changes in the course of a river. Such changes may be caused by interactions with a tributary, or by the opposing fluvial actions of deposition and/or erosion that form a natural cut and meander. Nascent vegetation-free shoals and mudflats may dissipate and shift or build up into such islands through deposition; the process may be assisted through artificial reinforcement or natural factors, such as reeds, palms, evergreen trees or willows, that act as obstacles or erosion barriers, so that water flows around them. Islands may be small or large, covering many square kilometers, examples of which are given below.

Regional nomenclature

The term "towhead" implies an islet (small island) or shoal within a river (most often the Mississippi River) having a grouping or thicket of trees, and is often used in the Midwestern United States. Many rivers, if wide enough, can house considerably large islands. The term "towhead" was popularised by Mark Twain's Adventures of Huckleberry Finn.

In England, a river island in the Thames is referred to as an "ait" (or "eyot").

Largest and smallest

Friday Island is an example of a very small island with a solid-foundations house.

Majuli (a non-coastal landmass between two banks of a river), located in the Brahmaputra River in Assam, India, is recognised by Guinness World Records as the world's largest inhabited riverine island, at 880 square kilometres (340 sq mi).[1]

The Encyclopædia Britannica cites another large non-coastal landmass, Bananal Island (an island that divides the Araguaia River into two branches over a 320 km (200-mile) length of water), located in Tocantins, central Brazil, to be the world's largest river island instead, at 19,162 square kilometres (7,398 sq mi).[2]

However, Bananal Island is not considered a riverine island by some geologists, as they consider the Araguaia River to form two distributaries, and Bananal Island to be the landmass between these two distributed rivers. However, Bananal Island is technically an island as it does not touch the main landmass at any point.

Umananda Island, at 0.02 square kilometres (0.0077 sq mi), is among contenders as the smallest permanently-inhabited river island, or islet, with fixed dwellings. Umananda also lies in the Brahmaputra River. Many as tiny as Umananda or smaller, inhabited, exist on the Amazon basin and Bangladesh. Another island of comparable size to Umananda, Hatfield Island in the Guyandotte River in the U.S. state of West Virginia, has no permanent population, but contains several permanent buildings, namely the K–12 schools serving the city of Logan and its surrounding area plus the main branch of the Logan County public library.[3]

On canalised rivers, such as the Thames and the Seine, one-home islands exist, containing houses constructed of permanent materials. Canals reduce erosion of the islands and in particular limit the height of flash flooding by maintaining substantial "heads" of water through barrages. One-home islands improved by river canals include Monkey, Friday, Holm and D'Oyly Carte islands.

Lists of river islands

River islands by area

Name Area
(km2)
Country River
Marajó40,100BrazilAmazon River / Pará River
Bananal Island19,162BrazilAraguaia River
Riverine Plain, Moulamein, Coleambally, Hay, Balranald18,000AustraliaFormed by the Billabong, Edward, and Murrumbidgee river systems in New South Wales.
Tupinambarana11,850BrazilAmazon River
Bahr al Jabal Island7,929South SudanBahr al Jabal Bahr el Zeraf
Holland/Utrecht7,361NetherlandsRhine River IJssel River
Ilha Grande de Gurupá4,864BrazilAmazon River
Margarita Island2,832[4]ColombiaMagdalena River
Uarini Island2,339BrazilUarini River, Amazon River
Boven Digul2,171IndonesiaDigul River, Kawaga River
Richards Island2,165CanadaMackenzie River
Krasnoslobodsk2,002RussiaVolga River, Akhtuba River
Veľký Žitný ostrov1,885.2[5]SlovakiaDanube, Little Danube
Hatiya Island1,508.23BangladeshMeghna River
Letea Island1,480RomaniaDanube
Camargue1,453FranceGrand Rhone, Petit Rhone
Bhola Island1,441BangladeshMeghna River
Chongming Island1,267[6]ChinaYangtze River
Ile à Morfil1,250SenegalSenegal River
Zhongshan Island1,055.42ChinaPearl River
Dibru Saikhowa765IndiaBrahmaputra River
Sandwip Island762.42BangladeshMeghna River
Great Brăila Island720.2RomaniaDanube
Majuli553IndiaBrahmaputra River
Sumba Island500[7]Democratic Republic of CongoCongo River
Montreal499CanadaSt. Lawrence River, Rivière des Prairies
Szigetköz375Hungary, SlovakiaDanube
Manpura Island373BangladeshMeghna
Inhacamba340MozambiqueZambezi
Hoeksche Waard323.74NetherlandsOude Maas, Nieuwe Maas
Yangzhong Island320ChinaYangtze River
Gunbower Island 264 Australia Murray River
Csepel Island257HungaryDanube
Jésus Island242CanadaRivière des Mille Îles, Rivière des Prairies
Voorne-Putten220NetherlandsOude Maas, Nieuwe Maas
Hisingen199SwedenGöta älv
Mosqueiro191BrazilAmazon River
Mbamou Island180[8]Republic of the CongoCongo River
Don Khong144LaosMekong
Roberts Island 133[9] United States San Joaquin River
Union Island 130[9] United States San Joaquin River
Davis Island120United StatesMississippi River
Taiama Island115.55BrazilParaguay River
Lulu Island112.4CanadaFraser River
Sarpinskiy Island110RussiaVolga River
Sauvie Island84.8United StatesColumbia River
Dordrecht Island79.53NetherlandsOude Maas, Hollands Diep
Srirangam74.4IndiaKaveri[10]
Grand Island73.8United StatesNiagara River
Rangitata Island~65New ZealandRangitata River[lower-alpha 1]
Ostrvo60SerbiaDanube
Hogg Island59GuyanaEssequibo River
Manhattan Island59United StatesHudson River/East River/Harlem Creek
Hengsha Island55.74ChinaYangtze River
Rusnė Island 45 Lithuania Neman
Wakenaam Island45GuyanaEssequibo River
Belene Island41BulgariaDanube
Woodford Island37AustraliaClarence River
Wilhelmsburg35.3GermanyElbe
Leguan Island31GuyanaEssequibo River
Grave di Papadopoli18ItalyPiave River
Isla Teja15ChileCau-Cau River/Cruces River/Valdivia River
Srirangapatna13IndiaKaveri
Shivanasamudram[11]IndiaKaveri
Grosse Ile25United StatesDetroit River
Inch Clutha~24New ZealandClutha River
Khortytsia23.59UkraineDnieper River
Island of Šarengrad9Disputed (Serbia/Croatia)Danube
Yeouido8.4South KoreaHan River
Tatyshev7RussiaYenisey River
Sedudu/Kasikili5BotswanaCuando River
Hayden Island4.4United StatesWillamette River
Nanjido2.8South Koreaa branch of the Han River
Otdyha Island2.5RussiaYenisey River
Wheeling Island1.5United StatesOhio River
Rŭngrado1.3North KoreaTaedong River
Yanggakdo1.2[12]North KoreaTaedong River
Nakanoshima0.7JapanKyū-Yodo River
Zhenbao Island0.7ChinaUssuri River
Bhavani Island0.53IndiaKrishna River
Bamseom0.24South KoreaHan River
Île de la Cité~0.2FranceSeine
Nakasu~0.2JapanNakagawa River
Prince's Island Park0.2CanadaBow River
Island of Vukovar0.032Disputed (Serbia/Croatia)Danube
Umananda Island0.02IndiaBrahmaputra River
Hatfield Island0.17United StatesGuyandotte River
Some Sevit
(Gavit,Chavit,Solvit,Yevit)
0.0104
(0.0048,0.0034,0.0012,0.0008)
South KoreaHan River
Pheasant Island0.00682Condominium between France and SpainBidasoa
  • Note: Includes some river islands that also have an ocean coast.

Most populous river islands

This list ranks river islands with a population of at least 25,000.

Name Population Area
(km2)
Country City River
Salsette Island15,111,974619IndiaMumbai and ThaneVasai Creek/Thane Creek
Île de Montréal1,942,044 (2016)[13]499CanadaMontrealRivière des Prairies/St. Lawrence River
Manhattan Island1,628,701 (2018)[14][lower-alpha 2]59United StatesNew York CityHudson River/East River
Chongming Island660,000 (2010)1,267ChinaShanghaiYangtze River
Jésus Island422,993 (2016)[15]242CanadaLavalRivière des Mille Îles/Rivière des Prairies
Veľký Žitný ostrov226,446 (2001)1,885SlovakiaBratislava, Komárno, Dunajská Streda and othersDanube, Little Danube
Vasilievsky Island209,188 (2017)10.9RussiaSt. PetersburgBolshaya Neva/Malaya Neva
Lulu Island198,309 (2016)[16]122.4CanadaRichmondFraser
Srirangam181,556 (2001)13IndiaSrirangamKaveri
Bangkok Noi179,814 (2017)18ThailandBangkokChao Phraya River
Majuli167,304 (2011)422IndiaVaishnavite ShrinesBrahmaputra River
Csepel Island166,953 (2012)257HungaryseveralDanube
Hisingen130,000199SwedenGothenburgGöta älv
Navotas Island117,1961.95PhilippinesNavotas, Metro ManilaTullahan River
Wilhelmsburg49,132 (2006)35.3GermanyHamburgElbe
Yeouido30,988 (2006)8.4South KoreaSeoulHan River
Mosqueiro27,000191BrazilBelémAmazon River

See also

  • Ait – Islands found on the River Thames and its tributaries in England
  • Anabranch – A section of a river or stream that diverts from the main channel and rejoins it downstream.
  • Archipelago – Collection of islands
  • Distributary – Stream branching off from main stream channel
  • Fluvial landforms – Sediment processes associated with rivers and streams
  • Island – Piece of subcontinental land completely surrounded by water
  • Lake island – Island located in a lake
  • Point bar – Landform related to streams and rivers
  • River bifurcation – The forking of a river into its distributaries
  • River delta – Silt deposition landform at the mouth of a river

Notes

  1. Due to redirecting of water from the Rangitata River, the river's southern distributary channel is now dry except after heavy rain or snow melt. As such, Rangitata Island is usually connected to the South Island mainland.
  2. The listed population is that of the New York City borough of Manhattan. Almost all of the borough's population lives on the island of Manhattan, but the borough also includes the following permanently populated areas:
    • Marble Hill, a neighborhood with a population of roughly 10,000 that was originally part of Manhattan Island, but was physically separated from the rest of the island by the opening of a canal in 1894 and in turn physically connected to the US mainland by landfill in 1914.
    • Randalls and Wards Islands, the collective name for three conjoined islands with about 1,600 residents, all either patients or staff of psychiatric hospitals, or occupants of homeless shelters.
    • Roosevelt Island, located in the East River between Manhattan Island and Queens, with a population of nearly 12,000.

References

  1. Majuli, River Island. "Largest river island". Guinness World Records. Retrieved 6 September 2016.
  2. Ilha do Bananal, River Island. "Bananal Island". Britannica. Retrieved 5 August 2020.
  3. Spence, Robert Y. (February 21, 2012). "Hatfield Island". The West Virginia Encyclopedia. Retrieved June 12, 2020.
  4. "Río Grande de la Magdalena - Colección Ecológica del Banco". Retrieved 3 January 2015.
  5. "Žitný ostrov". Retrieved 3 January 2015.
  6. "崇明县". www.shanghai.gov.cn.
  7. "Largest Islands of Countries". Retrieved 3 January 2015.
  8. "Malebo Pool". Encyclopædia Britannica. Accessed June 2017.
  9. 1 2 "SUMMARY REPORT ROBERTS ISLAND AND UNION ISLAND RIPARIAN WATER RIGHTS INVESTIGATION, SAN JOAQUIN COUNTY, CA, JUNE 2008" (PDF).
  10. W. Francis (1906). Gazetteer of South India. p. 199.
  11. Shivanasamudra
  12. Historical Dictionary of Pyongyang, by Justin Corfield, p.227
  13. "2016 Census Profile - Montréal, Territoire équivalent (Census division)". Statistics Canada. 8 February 2017. Retrieved 2017-03-23.
  14. "U.S. Census Bureau QuickFacts: New York County (Manhattan Borough), New York; United States". www.census.gov. Retrieved 2019-09-12.
  15. "2016 Census Profile - Laval, Territoire équivalent (Census division)". Statistics Canada. 8 February 2017. Retrieved 2019-09-11.
  16. "2016 Census Profile - Richmond (Census division)". Statistics Canada. 8 February 2017. Retrieved 2019-09-11.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.