A river is heading towards its mouth: on a map, the arrow appears unambiguous. But near the sea, its flow can meet a force coming from opposite. The passage of Isaac in Louisiana, in August 2012, offered a spectacular illustration.
In its account of the storm, NASA describes a surge that pushed north from the waters of the Mississippi that normally flowed south. The current has thus reversed in the area affected by the storm. It wasn’t the entire U.S. river system going back to its source.
The expression “sink backwards” therefore takes on a precise meaning when one returns its local scale and its temporary character. The river has not definitively changed its destination. The event above all shows how a mouthpiece is a meeting place: during a storm, the marine thrust can become strong enough to thwart the expected movement.
What we know
Local and temporary inversion reported at Isaac in 2012; no inversion of the entire Mississippi to its source.
To go to the source
References consulted on September 21, 2026. Linked pages may be in another language.
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