New Orleans Sinking Faster Than Thought

The federal government, especially the Army Corps of Engineers, hasn't taken the dramatic sinking into account in rebuilding plans, said University of Berkeley engineering professor Bob Bea, part of an independent National Academy of Sciences-Berkeley team that analyzed the levee failures during Katrina.

"You have to change how you provide short- and long-term protection," said Bea, a former engineer in New Orleans. He said plans for concrete walls don't make sense because they sink and can't be easily added onto. In California, engineers are experimenting with lighter weight, reinforced foam-middle levee walls, he said.

Dixon and his co-author Dokka disagree on the major causes of New Orleans' not-so-slow fall into the Gulf of Mexico.

Dixon blames overdevelopment and drainage of marshlands, saying "all the problems are man-made; before people settled there in the 1700s, this area was at sea level."

But Dokka said much of the sinking is due to natural seismic shifts that have little to do with construction.

Dokka also thinks all is not completely lost. Smarter construction can buy New Orleans some time.

"We've made the pact with the devil by moving down here," he said. "If we do things right, we probably can get another 100-200-300 years out of this area."

The Army Corps of Engineers is adding extra height to earthen levees to compensate for sinking and is setting benchmark measurements of all levees for regular monitoring of how much they sink, corps spokesman Gene Pawlik said.

"It's something post-Katrina, we're much more focused on," Pawlik said Wednesday. "It's certainly an engineering challenge."