This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Sunday, March 20, 2011

More on whirlpools!

Naruto Strait whirlpool from Mantokun, Wikimedia 
"Whirlpool" is a general term for any swirling body of water. Whirlpools on many scales are common in nature, and they are easily seen in almost any flowing body of water.  In rafting on the Colorado River through the Grand Canyon, it is not uncommon to have one end of a 16' rubber raft sucked down 6" or more by little whirlpools in the river.  According to Wiki on Whirlpools, the 5 strongest whirlpools in the world are in Norway (2), Maine (USA), Japan and Scotland, and these have speeds that reach up to 37 km/hour (23 mph).

The natural whirlpools in Japan occur in the Naruto Strait, a channel between two smal islands, Tokushima and Awiji.  The straight is less than 1 mile in width, and connects the Pacific Ocean and the Inland Sea, a body of water that separates Honshu and Shikoku. Tides here have a range up to 5.6 feet, creating a difference in water level of nearly 5' between the Inland Sea and the Pacific. Because the strait is so narrow, water rushes through it at 8-9 mph, four times per day, and during spring tides the speed can reach 12 mph.  At that time, whirlpools up to 66' in diameter can occur.

The whirlpool in your bathtub is not a good analog for most natural whirlpools because it is caused by the exodus of water down your drain. However, there was one similar whirlpool in a lake in Louisiana in 1980 when a drilling rig broke through the roof of an underground salt mine.  The lake drained, just like bathwater, down through the salt mine and a whirlpool developed.  Although some boats and semi trailers were caught up in it, no lives were lost.


lightsinthedark said...

I remember reading about a particularly large whirlpool in Maine called "Old Sow"....is that still in effect, to your knowledge?

I am wondering how climate change and sea level rise might affect the structure of whirlpools around tidal regions in the coming decades. Will they become stronger? Or less intense?

Susan W. Kieffer said...

Old Sow is the whirlpool mentioned as being in Maine in the blog. There is a good Wiki article on it, discussing first the etymology of the name. It may derive from "pig-like" noises that the whirlpool makes, or may be related to the word "sough" meaning a "drain." I can't answer your question about climate change and sea level rise, but my gut feeling is that the structure will be affected because the whirlpools are sensitive to the strength of the tides, which will likely change as sea level changes. The Wiki article says that in the 1930's a series of dikes were constructed to try to harness the tidal power and that these dikes affected the water flow and the whirlpool predictability. This suggests a fairly strong sensitivity to local conditions.

Michelle Anne Custodio said...

You can visit corryvreckan whirlpool. It'll be a good adventure.