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Earth Sense: Indian city, New Orleans in danger of floods
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Concerns about climatic change, and the sea level rise that comes with it, wouldn’t be so urgent if there weren’t so many of the world’s major cities on coastlines.

A British newspaper recently named Surat in the state of Gujarat, India, as one of the places that will bear the main brunt of future weather.

No one is predicting a “global heat wave” or something outrageous like that. It’s enough to get more variability of rain, and some unusual weather, to have dangerous conditions in some places.

In Arkansas, winter storm Troy dumped more than 6 inches of rain on the region around Little Rock on March 30, causing a flash flood that necessitated several rescue operations.

With an elevation of 30 to 40 feet above sea level, Surat is in a much more precarious position than Little Rock. In addition, the city has 4.5 million inhabitants. That’s the same as the urban population of greater Atlanta, but concentrated in a smaller space.

Like most places in India, Surat gets heavy monsoon rains every summer. But there’s also the mouth of the Tapi River, a major estuary draining into the Arabian Sea at India’s West Coast. Tidal flooding has been common in the past. An increase in the frequency of rain storms, combined with rising sea level and possibly a cyclone (hurricane), would repeat the Surat flood of 2006 on a much bigger scale.

That event 10 years ago, killing between 120 and 500 people depending on whose estimate you rely upon, was produced partly by heavy rain upstream and partly by mismanagement of water release from a dam.

The sudden onrush of stormwaters down the Tapi River flooded 75 percent of the city. Even with better lake management, it will happen eventually that two things occur at the same time.

An ocean-born storm will push waves upriver. Rushing against that will be flood drainage from farther inland. Sadly, Surat has been ranked among the cleanest communities in India, and much of that progress could be lost.

Coastal cities where residents are at risk of two flood waves moving against each other are common.

In the U.S., New Orleans is a sitting duck for new disaster. Levees have been repaired since the devastating flood caused by Hurricane Katrina in 2005.

No one can change the city’s elevation, though, which is at and below ocean level.
 
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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