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Earth Sense: Thames flows in rare way
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If your travels lead you to London, there are interesting things to observe besides the museums, shops and the slightly scary London Eye Ferris wheel.

One is that the Thames River seems to be changing its direction numerous times as you walk or drive through the city. Near Canary Wharf is a street called Marsh Wall. On one end, the Thames is flowing from north to south. On the other end of Marsh Wall, it’s south to north. How is this possible?

Rivers don’t normally change their flow direction. The Thames can only do that when a very strong tide pushes water upriver from the North Sea. But that’s much farther to the east, near Southend-on-Sea.

In London, the river flows in steep curves called meanders. They established themselves long before London was even a hamlet.

When a river crosses flat terrain, as it does in London, its flow describes a three-dimensional corkscrew pattern. The water turns over, going up on one side and down on the other. This also makes it swing from side to side.

Over time, curves develop and get increasingly tight. It can even happen that a meander cuts itself off when the river approaches 360 degrees of turn, and cuts into the spot it has just flowed through. In that case, the loop is cut off and the river takes the new, shorter course. That’s what happened between Weybridge and Shepperton, some 20 miles farther west.

Another interesting point about the Thames is that it widens considerably near the eastern edge of the city, and forms a large estuary where it meets the North Sea. Many storms have pushed water back up the river and flooded London.

On Jan. 7, 1928, such a flood inundated much of the central city area. It happened after midnight, catching the population unaware. As is the case so often, the poorest residents were hit hardest. To the present day, you can see thousands of “walk-down” apartments in the city, located one floor lower than street level. Lives were lost as these filled with Thames waters.

In 1982, the London Barrier was completed. It’s worth a drive or bus ride to Silvertown to see that enormous set of gates, closing automatically when flooding threatens the city. Camera enthusiasts know to wait for the late-afternoon sun, throwing colorful reflections off the steel gates.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.

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