From the Beeb
Parts of New Orleans had been sinking much faster than previously thought before Hurricane Katrina hit last August, new research suggests. Subsidence may explain why some levees were easily breached by floodwaters, the study in the Nature journal says. It says some very low-lying areas of the US city should not be rebuilt, describing them as "death traps". US engineers say the city is prepared for the start of the hurricane season, which officially starts on Thursday.
However, some storm experts think the work of rebuilding the levees is incomplete. ... 'Death traps' The study to be published on Thursday in the international science journal was produced by a University of Miami team.
It is based on new satellite radar data taken from 2002 to 2005, which show that New Orleans sank by an average of 0.22 inches (0.5cm) a year during that period. But the study says some low-lying areas are subsiding by more than one inch (2.54cm) a year - raising concerns about the city's future. The scientists name overdevelopment, drainage and natural seismic shifts as the main causes.
Unsaid is that when you saturate land that is normally dry by flooding it for over a week, it becomes even softer than usual and subsides faster than usual.
I don't think New Orleans will ever be rebuilt. Think of the yellow-orange specks on that map as leaks in the dike. They show Ponchartrain merging with the Mississippi. The French Quarter as an island.
I could be wrong. Venice is still there.