Scientist already knew that New Orleans was sinking. But a new study finds that the Big Easy and its environs are losing elevation (a process called subsidence) at a faster rate than previously thought—some two inches per year near the Mississippi River and in industrial areas, and more than an inch-and-a-half in the Upper and Lower Ninth Ward, the Christian Science Monitor reports. The Weather Channel sums up the issue: "When a city already sits below sea level, any additional sinking is a cause for major concern." The new information was collected between 2009 and 2012 using radar images taken from an aircraft flying the same route year after year, per the Advocate. Scientists from NASA's Jet Propulsion Laboratory, UCLA, and LSU participated. Their findings were published this month in the Journal of Geophysical Research.
The new data will help planners more effectively reverse the effects of subsidence, thus "improving the long-term coastal resiliency and sustainability of New Orleans," says lead author Cathleen Jones, per Phys.org. "The more recent land elevation change rates from this study will be used to inform flood modeling and response strategies, improving public safety." Previous data was collected with lower resolution radar, the CSM notes, and didn't provide the full picture of subsidence in the region. The sinking is, in large part, caused by pumping groundwater and surface water. Earth being weighed down by deposited sediments, as well as removal of oil and gas, also play a role. A rise in sea levels (some three inches since 1992) also is a factor. "People need to understand that the planet is not only changing, it's changed," a NASA scientist says. (New Orleans is not alone: Phoenix is slowly sinking, as are parts of California.)