With the sea rising around it, New Orleans could be headed for new lows.

Credit: Falk Amelung/University of Miami

In the midst of preparing for the arrival of another intense hurricane season, the city of New Orleans is continuing to rebuild from the decimation caused by Hurricane Katrina less than a year ago. 

Urban planners in the Big Easy have their work cut out for them. But in addition to protecting the city from future storms, scientists are recommending that it be rebuilt as a sinking city. 

According to researchers at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, New Orleans is sinking—in some areas up to 20mm per year. This phenomenon, combined with the expected worldwide rise in sea levels resulting from melting glaciers, means that, over the course of 100 years, the city could fall further under sea level, with levees falling several meters below the level where they were originally built. The group says this subsiding should be kept in mind with future levee designs.

“They are happy to fix those levees, but they haven’t had time to do a new design,” said Falk Amelung, a professor of geophysics at Miami and coauthor of the study. “When they really do a new design and want to build levees that can handle a category 5 hurricane, they must take this subsiding into account.” 

In its research, published in the June 1st issue of Nature, researchers used a Canadian satellite equipped with radar technology to obtain map-images of New Orleans. The images were taken at different times from the same spot in the satellite’s orbit. Using “exploits points,” or man-made structures on the ground that strongly reflect radar, scientists were able to calculate the rate at which parts of the city are sinking. 

This drop may have contributed to their inability to protect New Orleans from Katrina last year.

“In the Mississippi River-Gulf Outlet Canal, where we have a high subsidence rate, the levees were completely overtopped and St. Bernard Parish was heavily flooded because of it,” said Amelung

According to the team’s estimates, some of the current levees may now stand three feet shorter than when they were built 40 years ago. By 2106, for example, they believe the ground will be nearly three feet lower on average than it is now.

“Its very important that the levees are updated frequently to account for the sinking,” said Amelung. “That means every few years: make them higher. Or from the very beginning, making a high levee that is up to the cause.”

While engineers have a tough task ahead, so do researchers, who are still in search of just what is causing the city to subside. Some believe the city is slumping into the gulf due to tectonic shifts while others point fingers at a large drainage system that is at work at the Mississippi Delta.

“[The rate of subsiding] may be a combination of both, at this point we don’t know,” said Amelung. “If it has deep roots, then it will continue to sink as we see it now, and that is bad news for New Orleans.” 

New Orleans isn’t the only city slowly crawling into the nearest body of water; Venice has been falling into the Adriatic Sea for years. City engineers devised a controversial system of gates to protect the lagoon from rising tides, said John Keahey, author of Venice Against the Sea. New Orleans’ fragile delta location makes it even more difficult to save from rising tide levels. 

“Gates will not be the solution for New Orleans, they need a whole new concept of neighborhoods and rebuilding,” said Keahey. “They have to ask if homes should be allowed to be reconstructed if they were built in swamplands below sea level.”

Originally published June 1, 2006


Share this Stumbleupon Reddit Email + More


  • Ideas

    I Tried Almost Everything Else

    John Rinn, snowboarder, skateboarder, and “genomic origamist,” on why we should dumpster-dive in our genomes and the inspiration of a middle-distance runner.

  • Ideas

    Going, Going, Gone

    The second most common element in the universe is increasingly rare on Earth—except, for now, in America.

  • Ideas

    Earth-like Planets Aren’t Rare

    Renowned planetary scientist James Kasting on the odds of finding another Earth-like planet and the power of science fiction.

The Seed Salon

Video: conversations with leading scientists and thinkers on fundamental issues and ideas at the edge of science and culture.

Are We Beyond the Two Cultures?

Video: Seed revisits the questions C.P. Snow raised about science and the humanities 50 years by asking six great thinkers, Where are we now?

Saved by Science

Audio slideshow: Justine Cooper's large-format photographs of the collections behind the walls of the American Museum of Natural History.

The Universe in 2009

In 2009, we are celebrating curiosity and creativity with a dynamic look at the very best ideas that give us reason for optimism.

Revolutionary Minds
The Interpreters

In this installment of Revolutionary Minds, five people who use the new tools of science to educate, illuminate, and engage.

The Seed Design Series

Leading scientists, designers, and architects on ideas like the personal genome, brain visualization, generative architecture, and collective design.

The Seed State of Science

Seed examines the radical changes within science itself by assessing the evolving role of scientists and the shifting dimensions of scientific practice.

A Place for Science

On the trail of the haunts, homes, and posts of knowledge, from the laboratory to the field.


Witness the science. Stunning photographic portfolios from the pages of Seed magazine.

SEEDMAGAZINE.COM by Seed Media Group. ©2005-2015 Seed Media Group LLC. All Rights Reserved.

Sites by Seed Media Group: Seed Media Group | ScienceBlogs | Research Blogging | SEEDMAGAZINE.COM