River island

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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 land surrounded by river water. Properly defined it excludes shoals between seasonally varying flows and may exclude semi-coastal islands such as in deltas.

These islands result from changes in the course of a river such as interactions with a tributary or the opposing fluvial actions of deposition and/or erosion such as forming a natural cut and meander. Nascent vegetation-free shoals and mudflats may dissipate and shift or build up into such islands through deposition and which may be assisted through artificial reinforcement or natural factors such as, reeds, palms, evergreen trees or willows, to large examples covering many square kilometers, examples of which are given below.

Regional nomenclature[edit]

The term "towhead" implies a little islet 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[edit]

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

Majuli in India, being non-coastal and being between two channels of one river is recognised by the Guinness Book of World Records as world's largest example.,[1] but Ilha do Bananal meets the same qualifications and is much larger. Umananda is among contenders as the smallest permanently-inhabited river island with fixed dwellings at 0.02 km². Majuli and Umananda lie in the Brahmaputra River. Many as tiny as Umananda or smaller, inhabited, exist in the Amazon basin and Bangladesh. On canalised rivers such as the Thames and the Seine one-home islands of permanent-materials homes exist such as Monkey, Friday, Holm and D'Oyly Carte islands, as canalisation reduces the erosion of the islands and in particular limits the height of flash flooding by maintaining substantial "heads" of water through barrages.

Lists of river islands[edit]

  • Note: Includes some river islands that also have an ocean coast.
Name Area (km²) Country River
Marajó 40,100 Brazil Amazon River / Pará River
Ilha do Bananal 19,162 Brazil Araguaia River
Tupinambarana 11,850 Brazil Amazon River
Bahr al Jabal Island 7,929 South Sudan Bahr al Jabal Bahr el Zeraf
Holland/Utrecht 7,361 Netherlands Rhine River IJssel River
Ilha Grande de Gurupá 4,864 Brazil Amazon River
Margarita Island (Colombia) 2,832[2] Colombia Magdalena River
Uarini Island 2,339 Brazil Uarini River, Amazon River
Boven Digul 2,171 Indonesia Digul River, Kawaga River
Richards Island 2,165 Canada Mackenzie River
Krasnoslobodsk 2,002 Russia Volga River, Akhtuba River
Veľký Žitný ostrov 1,885.2[3] Slovakia Danube
Hatiya Island 1,508.23 Bangladesh Meghna River
Letea Island 1,480 Romania Danube River
Camargue 1,453 France Grand Rhone, Petit Rhone
Bhola Island 1,441 Bangladesh Meghna River
Chongming Island 1,267[4] China Yangtze River
Majuli 1,250 India Brahmaputra River
Ile à Morfil 1,250 Senegal Senegal River
Dibru Saikhowa 765 India Brahmaputra River
Sandwip Island 762.42 Bangladesh Meghna River
Great Brăila Island 720.2 Romania Danube
Sumba Island 500[5] Democratic Republic of Congo Congo River
Montreal 499 Canada St. Lawrence River, Ottawa River
Szigetköz 375 Hungary, Slovakia Danube
Manpura Island 373 Bangladesh Meghna
Inhacamba 340 Mozambique Zambezi
Hoeksche Waard 323.74 Netherlands Oude Maas, Nieuwe Maas
Yangzhong Island 320 China Yangtze
Csepel Island 257 Hungary Danube
Île Jésus 242 Canada Rivière des Mille Îles, Rivière des Prairies
Voorne-Putten 220 Netherlands Oude Maas, Nieuwe Maas
Hisingen 199 Sweden Göta älv
Mosqueiro 191 Brazil Amazon River
Mbamou Island 180[6] Republic of the Congo Congo River
Roberts Island 133[7] United States San Joaquin River
Union Island 130[7] United States San Joaquin River
Davis Island 120 United States Mississippi River
Taiama Island 115.55 Brazil Paraguay River
Lulu Island 112.4 Canada Fraser River
Sarpinskiy Island 110 Russia Volga River
Sauvie Island 105 United States Columbia River
Dordrecht Island 79.53 Netherlands Oude Maas, Hollands Diep
Srirangam 74.4 India Kaveri[8]
Grand Island 73.8 United States Niagara River
Rangitata Island ~65 New Zealand Rangitata River[notes 1]
Ostrvo 60 Serbia Danube
Manhattan Island 59 United States Hudson River/East River/Harlem Creek
Hengsha Island 55.74 China Yangtze River
Woodford Island 37 Australia Clarence River
Wilhelmsburg 35.3 Germany Elbe
Isla Teja 15 Chile Cau-Cau River/Cruces River/Valdivia River
Srirangapatna 13 India Kaveri
Shivanasamudram [9]India Kaveri
Grosse Ile 25 United States Detroit River
Inch Clutha ~24 New Zealand Clutha River
Khortytsia 23.59 Ukraine Dnieper River
Island of Šarengrad 9 Disputed (Serbia/Croatia) Danube
Yeouido 8.4 South Korea Han River
Sedudu/Kasikili 5 Botswana Cuando River
Hayden Island 4.4 United States Willamette River
Nanjido 2.8 South Korea a branch of the Han River
Rŭngrado 1.3 North Korea Taedong River
Yanggakdo 1.2[10] North Korea Taedong River
Nakanoshima 0.7 Japan Kyū-Yodo River
Zhenbao Island 0.7 China Ussuri River
Bhavani Island 0.53 India Krishna River
Bamseom 0.24 South Korea Han River
Île de la Cité ~0.2 France Seine
Nakasu ~0.2 Japan Nakagawa River
Island of Vukovar 0.032 Disputed (Serbia/Croatia) Danube
Umananda Island 0.02 India Brahmaputra River
Some Sevit
(Gavit,Chavit,Solvit,Yevit)
0.0104
(0.0048,0.0034,0.0012,0.0008)
South Korea Han River
Pheasant Island 0.00682 Condominium between France and Spain Bidasoa

Most populous river islands[edit]

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

Name Population Area [km²] Country City River
Salsette Island 15,111,974 619 India Mumbai and Thane Ulhas River
Île de Montreal 1,942,044 (2016)[11] 499 Canada Montreal St. Lawrence River
Manhattan Island 1,628,701 (2018)[12] 59 United States New York City Hudson River/East River
Chongming Island 660,000 (2010) 1,267 China Shanghai Yangtze River
Île Jesus 422,993 (2016)[13] 242 Canada Laval St. Lawrence River
Veľký Žitný ostrov 226,446 (2001) 1,885 Slovakia several Danube
Vasilievsky Island 209,188 (2017) 10.9 Russia St. Petersburg Bolshaya Neva/Malaya Neva
Lulu Island 198,309 (2016)[14] 122.4 Canada Richmond Fraser
Srirangam 181,556 (2001) 13 India Srirangam Kaveri
Majuli 167,304 (2011) 422 India Vaishnavite Shrines Brahmaputra River
Csepel Island 166,953 (2012) 257 Hungary several Danube
Hisingen 130,000 199 Sweden Gothenburg Göta älv
Wilhelmsburg 49,132 (2006) 35.3 Germany Hamburg Elbe
Yeouido 30,988 (2006) 8.4 South Korea Seoul Han River
Mosqueiro 27,000 191 Brazil Belém Amazon River

See also[edit]

  • 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 – A group of islands
  • Distributary
  • Fluvial landforms – Processes associated with rivers and streams
  • Island – Any piece of sub-continental land that is surrounded by water
  • Lake island
  • Point bar – A depositional feature of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope
  • River bifurcation
  • River delta – Silt deposition landform at the mouth of a river

Notes[edit]

  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.

References[edit]

  1. ^ Majuli, River Island. "Largest river island". Guinness World Records. Retrieved 6 September 2016.
  2. ^ "Río Grande de la Magdalena - Colección Ecológica del Banco". Retrieved 3 January 2015.
  3. ^ "Žitný ostrov". Retrieved 3 January 2015.
  4. ^ address, author,email. "崇明县". www.shanghai.gov.cn.
  5. ^ "Largest Islands of Countries". Retrieved 3 January 2015.
  6. ^ "Malebo Pool". Encyclopædia Britannica. Accessed June 2017.
  7. ^ a b "SUMMARY REPORT ROBERTS ISLAND AND UNION ISLAND RIPARIAN WATER RIGHTS INVESTIGATION, SAN JOAQUIN COUNTY, CA, JUNE 2008" (PDF).
  8. ^ W. Francis (1906). Gazetteer of South India. p. 199.
  9. ^ Shivanasamudra
  10. ^ Historical Dictionary of Pyongyang, by Justin Corfield, p.227
  11. ^ "2016 Census Profile - Montréal, Territoire équivalent (Census division)". Statistics Canada. Retrieved 2017-03-23.
  12. ^ "U.S. Census Bureau QuickFacts: New York County (Manhattan Borough), New York; United States". www.census.gov. Retrieved 2019-09-12.
  13. ^ "2016 Census Profile - Laval, Territoire équivalent (Census division)". Statistics Canada. Retrieved 2019-09-11.
  14. ^ "2016 Census Profile - Richmond (Census division)". Statistics Canada. Retrieved 2019-09-11.