El Nino poses threat to Charleston

During the last El Nino season in late 2009 and early 2010, storms turned some of Charleston's quick-to-flood streets into canals. A new study says future El Ninos are likely to make things here even messier.

After the 2009-2010 El Nino, scientists with the National Oceanic and Atmospheric Administration examined five decades of data on water levels in Charleston, Boston, Atlantic City, N.J., and Norfolk, Va.

They found that in El Nino years, these areas generally had three times as many storm surges as normal. Typical sea levels were about four inches higher than meteorologists expected.

That extra four inches can mean a lot in a place like the Lowcountry, where land and water trade places with every tide. "It just adds a higher baseline that your tides and storm surges are working on," said Bill Sweet of NOAA, and the study's co-author.

During the last El Nino, flooding was particularly severe in low-lying areas of downtown Charleston; kayakers paddled down several streets for fun during several storms, while rising waters claimed parked cars and made some streets impassable.

No El Nino is expected to form this year, but when it does return, it's likely to generate higher sea levels and more storm surges. Sweet said the data should help city planners better prepare for future flooding.

"Charleston is such a beautiful area, but it's got a problem," he said.

The El Nino forms periodically when the water temperatures rise in the southern Pacific Ocean. Its formation ripples across the globe, triggering droughts, crop failures, floods and unrest tied to these disruptions. In the South, El Ninos generally bring more rain and cooler-than-normal temperatures.

Future El Nino seasons could be more destructive because sea levels are rising because of global warming and land on some parts of the East Coast is slowly settling and sinking, the study said. The study was published this month in the journal Monthly Weather Review of the American Meteorological Society.

Work recently began on an $11.3 million project on the Crosstown, most of which will be used for new and larger drainage pipes. That work is part of a much larger effort to reduce flooding in a flood basin roughly between The Citadel and the hospital complexes. The city still needs more than $120 million to finish work on that project and millions of dollars more to address flooding in other low-lying places.