List of rivers that have reversed direction

Reversing Falls of Saint John River

A number of rivers are known to have reversed the direction of their flow, either permanently or temporarily, in response to geological activity, weather events, climate change, tides, or direct human intervention.

Permanent reversals

Natural

River	Original outlet	Current outlet	Continent	Date of reversal	Cause of reversal	References
Amazon River	Pacific Ocean	Atlantic Ocean	South America	Cretaceous period	Formation of Andes Mountains	[1]
Wisconsin River	Great Lakes Basin	Mississippi River	North America	Pleistocene Epoch	Pre-Illinoian glaciers	[2]

Artificial

River	Original outlet	Current outlet	Continent	Date of reversal	Cause of reversal	References
Chicago River	Lake Michigan	Mississippi River	North America	1900	Construction of Chicago Sanitary and Ship Canal	[1]

Temporary reversals

Daily

All tidal sections of rivers reverse their flow with the tide about twice a day (or semidiurnally), by definition. The following are notable examples. ^[3]

River	Outlet	Continent	References
Hudson River	Upper New York Bay	North America	[3]
Saint John River (Reversing Falls)	Bay of Fundy	North America	[4]
Salmon River	Bay of Fundy	North America	[5]
Channel of Vivari	Straits of Corfu	Europe	[6]

Annual

River	Outlet	Continent	Cause of reversal	References
Krupa River	Neretva River	Europe	High water levels of the Neretva River	[7]
Petexbatún River	Pasión River	Central America	Winter rain flooding of the Pasión River	[8]
Qiantang River	Hangzhou Bay	Asia	Tidal bore in Hangzhou Bay	[9]
Tonlé Sap River	Mekong River	Asia	Monsoon flooding of the Mekong River	[10]

Intermittent

Hurricane storm surges often cause temporary reversals of coastal rivers. ^[1]

River	Outlet	Continent	Date of reversal	Cause of reversal	References
Chicago River [a]	Mississippi River	North America	2017 and others [b]	Storm surge	[11]
Mississippi River	Gulf of Mexico	North America	1812	Tectonic uplift caused by New Madrid earthquakes	[12]
			2005	Storm surge from Hurricane Katrina	[1]
			2012	Storm surge from Hurricane Isaac	[1] [13]
			2021	Storm surge from Hurricane Ida	[14]

1. These reversals represent a return to the Chicago River's original natural outlet in Lake Michigan.
2. Reversals of the Chicago River have been increasing in frequency in association with global warming, and may soon occur at least once each year. ^[11]

See also

• Stream capture, in which a stream or river is diverted from its own bed, and flows instead down a neighboring channel

References

1. Borneman, Elizabeth (November 24, 2014). "Rivers that Flow Backwards". Geo Lounge. Retrieved 18 March 2019.
2. "When the Wisconsin River Flowed East". 11 September 2018.
3. "The Hudson Estuary: A River That Flows Two Ways". New York State Department of Environmental Conservation . Retrieved 19 March 2019.
4. "Reversing Falls". New-Brunswick.net. Retrieved 18 March 2019.
5. Dinshaw, Fram (June 19, 2018). "What a bore! Truro's 'marvellous' tidal event a daily tourist draw | SaltWire". www.saltwire.com. Retrieved 2023-02-06.
6. Butrint National Park - Combining Natural Park with Cultural Heritage Retrieved 8 May 2024.
7. Krupa River Retrieved 30 August 2022.
8. The Petexbatún eco-system (in Spanish) Retrieved 30 January 2021.
9. The Bore Tides of the Qiantang River Retrieved 30 January 2021.
10. Jennings, Ken (February 2, 2015). "Why the Tonle Sap River Is Unlike Any Other River in the World". Condé Nast Traveler . Retrieved 18 March 2019.
11. "How Climate Change Is Making This River Run Backwards". EcoWatch. Natural Resources Defense Council. June 4, 2017. Retrieved 19 March 2019.
12. Soniak, Matt (January 25, 2013). "Has a U.S. River Run Backwards Before?". Mental Floss. Retrieved 18 March 2019.
13. "Mississippi River Flows Backwards Due to Isaac". USGS Newsroom. United States Geological Survey. August 29, 2012. Retrieved 19 March 2019.
14. "Hurricane Ida Is So Strong It Reversed the Mississippi's Current". interestingengineering.com. 2021-08-30. Retrieved 2021-08-30.