View source for Earth:List of rivers that have reversed direction

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A number of [[Earth:River|river]]s are known to have reversed the direction of their flow, either permanently or temporarily, in response to geological activity, weather events, [[Earth:Climate change|climate change]], or direct human intervention.

==Permanent reversals==
===Natural===
{| class="wikitable" style="text-align:center"
! River !! Original outlet !! Current outlet !! Continent !! Date of reversal !! Cause of reversal !! References
|-
| '''Amazon River''' || Pacific Ocean || Atlantic Ocean || South America || data-sort-value="1 Jan -145000000" | [[Earth:Cretaceous|Cretaceous]] period || [[Earth:Mountain formation|Formation]] of [[Place:Andes|Andes]] Mountains || <ref name="Borneman"/>
|-
| '''Wisconsin River''' || Great Lakes Basin || Mississippi River || North America || [[Earth:Pleistocene|Pleistocene Epoch]] || [[Earth:Pre-Illinoian|Pre-Illinoian]] glaciers || <ref>{{Cite web|url=https://www.wiscontext.org/when-wisconsin-river-flowed-east|title = When the Wisconsin River Flowed East|date = 11 September 2018}}</ref>
|}

===Artificial===
[[File:Chicago-Sanitary-and-Ship-Canal.jpg|thumb|upright=1.1|Construction of the Chicago Sanitary and Ship Canal]]
{| class="wikitable" style="text-align:center"
! 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 || <ref name="Borneman"/>
|}

==Temporary reversals==
[[File:ReversingFalls inbound.jpg|thumb|upright=1.1|The Reversing Falls of the Saint John River, flowing upriver]]

===Daily===
All [[Earth:Tidal river|tidal sections of rivers]] reverse their flow with the tide about twice a day (or semidiurnally), by definition. The following are notable examples.<ref name="NY-DEC"/>

{| class="wikitable" style="text-align:center"
! River !! Outlet !! Continent !! References
|-
| '''Hudson River''' || Upper New York Bay || North America || <ref name="NY-DEC"/>
|-
| '''Saint John River''' (Reversing Falls) || Bay of Fundy || North America || <ref name="NB"/>
|-
| '''Salmon River'''  || Bay of Fundy || North America || <ref name="Salmon-Truro"/>
|}

===Annual===
{| class="wikitable" style="text-align:center"
! River !! Outlet !! Continent !! Cause of reversal !! References
|-
| '''Krupa River''' || Neretva River || Europe ||  High water levels of the Neretva River ||<ref>[https://medwetmanagers.net/hutovo-blato-between-the-past-the-present-and-the-future/ Krupa River] Retrieved 30 August 2022.</ref>
|-
| '''Petexbatún River''' || Pasión River || Central America || Winter rain flooding of the Pasión River ||<ref>[https://prensacomunitar.medium.com/riesgo-de-desastre-ecol%C3%B3gico-irreversible-se-est%C3%A1-secando-la-laguna-de-petexbat%C3%BAn-e000e5e8905 The Petexbatún eco-system] (in Spanish) Retrieved 30 January 2021.</ref>
|-
| '''Qiantang River''' || Hangzhou Bay || Asia || [[Physics:Tidal bore|Tidal bore]] in Hangzhou Bay ||<ref>[https://www.theatlantic.com/photo/2016/09/the-bore-tides-of-the-qiantang-river/500843/ The Bore Tides of the Qiantang River] Retrieved 30 January 2021.</ref>
|-
| '''Tonlé Sap River''' || Mekong River || Asia || [[Earth:Monsoon|Monsoon]] flooding of the Mekong River || <ref name="Jennings"/>
|}

===Intermittent===
Hurricane [[Physics:Storm surge|storm surge]]s often cause temporary reversals of coastal rivers.<ref name="Borneman"/>

{| class="wikitable" style="text-align:center"
! River !! Outlet !! Continent !! Date of reversal !! Cause of reversal !!References
|-
| '''Chicago River'''{{efn|group=intermittent|These reversals represent a return to the Chicago River's original natural outlet in Lake Michigan.}} || Mississippi River || North America || 2017 and others{{efn|group=regular|Reversals of the Chicago River have been increasing in frequency in association with [[Earth:Global warming|global warming]], and may soon occur at least once each year.<ref name="EcoWatch"/>}} || [[Physics:Storm surge|Storm surge]] || <ref name="EcoWatch"/>
|-
| rowspan="4" | '''Mississippi River''' || rowspan="4" | Gulf of Mexico || rowspan="4" | North America
| 1812 || [[Earth:Tectonic uplift|Tectonic uplift]] caused by New Madrid earthquakes || <ref name="Soniak"/>
|-
| 2005 || [[Physics:Storm surge|Storm surge]] from Hurricane Katrina || <ref name="Borneman"/>
|-
| 2012 || Storm surge from Hurricane Isaac || <ref name="Borneman"/><ref name="USGS-Isaac"/>
|-
|2021
|Storm surge from Hurricane Ida
|<ref>{{Cite web|date=2021-08-30|title=Hurricane Ida Is So Strong It Reversed the Mississippi's Current|url=https://interestingengineering.com/hurricane-ida-is-so-strong-it-reversed-the-mississippis-current|access-date=2021-08-30|website=interestingengineering.com|language=en-US}}</ref>
|}

{{Notelist|group=intermittent}}

==See also==
*[[Earth:Stream capture|Stream capture]], in which a stream or river is diverted from its own bed, and flows instead down a neighboring channel

==References==
{{reflist|refs=

<ref name="Borneman">{{cite web |last1=Borneman |first1=Elizabeth |title=Rivers that Flow Backwards |url=https://www.geolounge.com/rivers-flow-backwards/ |website=Geo Lounge |accessdate=18 March 2019 |date=November 24, 2014}}</ref>

<ref name="Soniak">{{cite web |last1=Soniak |first1=Matt |title=Has a U.S. River Run Backwards Before? |url=http://mentalfloss.com/article/33572/has-us-river-run-backwards |website=Mental Floss |accessdate=18 March 2019 |date=January 25, 2013}}</ref>

<ref name="NB">{{cite web |title=Reversing Falls |url=http://new-brunswick.net/Saint_John/reversingfalls/reversing.html |website=New-Brunswick.net |accessdate=18 March 2019}}</ref>

<ref name="Salmon-Truro">{{Cite news|last=Dinshaw |first=Fram |title=What a bore! Truro's 'marvellous' tidal event a daily tourist draw {{!}} SaltWire |url=https://www.saltwire.com/cape-breton/lifestyles/what-a-bore-truros-marvellous-tidal-event-a-daily-tourist-draw-219703/ |date= June 19, 2018|access-date=2023-02-06 |website=www.saltwire.com |language=en}}</ref>

<ref name="Jennings">{{cite news |last1=Jennings |first1=Ken |title=Why the Tonle Sap River Is Unlike Any Other River in the World |url=https://www.cntraveler.com/stories/2015-02-02/maphead-ken-jennings-cambodia-tonle-sap-river |accessdate=18 March 2019 |work=Condé Nast Traveler |date=February 2, 2015}}</ref>

<ref name="NY-DEC">{{cite web |title=The Hudson Estuary: A River That Flows Two Ways |url=https://www.dec.ny.gov/lands/4923.html |publisher=New York State Department of Environmental Conservation |accessdate=19 March 2019}}</ref>

<ref name="EcoWatch">{{cite web |title=How Climate Change Is Making This River Run Backwards |url=https://www.ecowatch.com/chicago-river-run-backwards-2429212108.html |website=EcoWatch |publisher=Natural Resources Defense Council |accessdate=19 March 2019 |date=June 4, 2017}}</ref>

<ref name="USGS-Isaac">{{cite news |title=Mississippi River Flows Backwards Due to Isaac |url=https://archive.usgs.gov/archive/sites/www.usgs.gov/newsroom/article.asp-ID=3387.html |accessdate=19 March 2019 |work=USGS Newsroom |publisher=United States Geological Survey |date=August 29, 2012}}</ref>

}}

{{rivers, streams and springs}}
{{river morphology}}

[[Category:Hydrology]]

{{Sourceattribution|List of rivers that have reversed direction}}