Focused on rivers lately, I wondered if what I heard years ago is true. Can the Seine
River in France actually flow backwards? Someone told me that a strong wind can cause the Seine to reverse its course in Paris and downstream, but is that true? I have come to conclude that it is basically not true. Other rivers, however, have been known to flow in reverse under special circumstances.
The city of Paris is only 80 feet above sea level with 227 miles to go before it flows into the Atlantic Ocean. I can imagine that someone walking along it in the City of Lights might come under the illusion that it’s flowing west instead of east when a serious wind is blowing. The Seine is France’s 3rd longest river at 485 miles in length, but most rivers, and The Seine is no exception, flow downhill. There have only been a few temporary river reversals in human history.
Tidal rivers like the Hudson can reverse flow when the tide is rolling in. Rivers with big tidal estuaries like the Potomac and the Thames can have an increase in saltiness when the nearby ocean affects them, but I know of only one river that reverses course when this regularly happens. The St John River in Canada’s New Brunswick is adjacent to the Bay of Fundy, which has the highest tides in the world. At low tide the river that empties into this bay develops a series of waterfalls and whirlpools that reverses the flow of this river near New Brunswick’s capital city. This phenomenon is known as the “Reversing Falls” and is quite a tourist attraction that Ruth and I have witnessed.
The Mississippi River has significantly reversed direction twice in modern history. Hurricane Issac in 2012 caused a reverse flow in the lower river for 24 hours. In 1811 an earthquake at New Madrid in Missouri’s Bootheel was so strong that church bells rang in Boston as a result and the river flowed north instead of south for a time while Reelfoot Lake was being created. There were actually 3 major quakes and thousands of aftershocks.
There is only one river that can completely reverse its flow, the 156-mile-long Chicago River. This first occurred in 1887 when engineers figured a way to take water from Lake Michigan and put it into the Mississippi River by totally reversing the Chicago River’s flow. By 1900 this became routine due to opening locks to divert sewage from Lake Michigan, the source of Chicago’s water supply. Today this can and does happen routinely.
Millions of years ago some of the streams that fed The Amazon River way up in the Andes were known to reverse flow and go west for a period of time. Erosion and now climate change have been rumored to cause the backward flow of local rivers in some places, like western Canada.