River island

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.

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

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 nomenclatureEdit

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 smallestEdit

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

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

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

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 in the Amazon Basin and Bangladesh.[citation needed] 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.[citation needed] One-home islands improved by river canals include Monkey, Friday, Holm and D'Oyly Carte islands.

Lists of river islandsEdit

River islands by areaEdit

  • Note: Includes some river islands that also have an ocean coast.
Name Area
(km²)
Country River
Marajó 40,100 Brazil Amazon River / Pará River
Bananal Island 19,162 Brazil Araguaia River
Riverine Plain, Moulamein, Coleambally, Hay, Balranald. 18,000 Australia Formed by the Billabong, Edward and Murrumbidgee river systems in NSW.
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[4] 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[5] Slovakia Danube, Little Danube
Hatiya Island 1,508.23 Bangladesh Meghna River
Letea Island 1,480 Romania Danube
Camargue 1,453 France Grand Rhone, Petit Rhone
Bhola Island 1,441 Bangladesh Meghna River
Chongming Island 1,267[6] China Yangtze 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
Majuli 553 India Brahmaputra River
Sumba Island 500[7] 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 River
Csepel Island 257 Hungary Danube
Jésus Island 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[8] Republic of the Congo Congo River
Roberts Island 133[9] United States San Joaquin River
Union Island 130[9] 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[10]
Grand Island 73.8 United States Niagara River
Rangitata Island ~65 New Zealand Rangitata River[a]
Ostrvo 60 Serbia Danube
Manhattan Island 59 United States Hudson River/East River/Harlem Creek
Hengsha Island 55.74 China Yangtze River
Rusnė Island 45 Lithuania Neman
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 [11]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
Tatyshev 7 Russia Yenisey 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
Otdyha Island 2.5 Russia Yenisey River
Wheeling Island 1.5 United States Ohio River
Rŭngrado 1.3 North Korea Taedong River
Yanggakdo 1.2[12] 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
Prince's Island Park 0.2 Canada Bow River
Island of Vukovar 0.032 Disputed (Serbia/Croatia) Danube
Umananda Island 0.02 India Brahmaputra River
Hatfield Island 0.17 United States Guyandotte 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 islandsEdit

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 Vasai Creek/Thane Creek
Île de Montréal 1,942,044 (2016)[13] 499 Canada Montreal Rivière des Prairies/St. Lawrence River
Manhattan Island 1,628,701 (2018)[14][b] 59 United States New York City Hudson River/East River
Chongming Island 660,000 (2010) 1,267 China Shanghai Yangtze River
Jésus Island 422,993 (2016)[15] 242 Canada Laval Rivière des Mille Îles/Rivière des Prairies
Veľký Žitný ostrov 226,446 (2001) 1,885 Slovakia Bratislava, Komárno, Dunajská Streda and others Danube, Little Danube
Vasilievsky Island 209,188 (2017) 10.9 Russia St. Petersburg Bolshaya Neva/Malaya Neva
Lulu Island 198,309 (2016)[16] 122.4 Canada Richmond Fraser
Srirangam 181,556 (2001) 13 India Srirangam Kaveri
Bangkok Noi 179,814 (2017) 18 Thailand Bangkok Chao Phraya River
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 alsoEdit

  • 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 – River branching off from main river
  • Fluvial landforms – Processes associated with rivers and streams
  • Island – Any piece of sub-continental land that is surrounded by water
  • Lake island – Island located in a lake
  • Point bar – 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

NotesEdit

  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.

ReferencesEdit

  1. ^ Majuli, River Island. "Largest river island". Guinness World Records. Retrieved 6 September 2016.
  2. ^ larger, Ilha do Bananal. "Bananal Island". Brittanica. 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. ^ address, author,email. "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. ^ a b "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. Retrieved 2019-09-11.
  16. ^ "2016 Census Profile - Richmond (Census division)". Statistics Canada. Retrieved 2019-09-11.