Naruto Strait whirlpool from Mantokun, Wikimedia |
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.
3 comments:
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?
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.
You can visit corryvreckan whirlpool. It'll be a good adventure.
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