NASA image: Subsidence in New Orleans
NASA Earth Observatory
Most people know that New Orleans has been sinking, but exactly how much has it sunk? In a paper published in the journal Nature, an international team of scientists determined the subsidence (sinking) in New Orleans in the three-year period prior to Hurricane Katrina. The team used data collected by Canada’s RADARSAT satellite between April 2002 and July 2005. The researchers found that most of New Orleans subsided 8 millimeters per year relative to global mean sea level during that period. [...]
Scientists have proposed several causes for subsidence in New Orleans. These causes range from natural ones, such as settling of coastal sediments and movement of the Michoud fault, to human ones such as draining wetlands, diverting sediment-bearing floodwaters from the Mississippi River, and pumping ground water.