A new NASA study has revealed that New Orleans and its surrounding environment are still sinking. Although this is no shock to many, the data provides the most detailed look at the problem yet and covers thousands of points throughout New Orleans and its suburbs, with some places sinking more than one-and-a-half inches each year.
"What we're trying to do is get set up to do this over the long term so we can see how it changes over time," said Cathleen Jones, a radar scientist at NASA's Jet Propulsion Laboratory in California and lead author of the study.
The study examined subsidence rates throughout New Orleans and its surrounding areas between the years 2009 and 2012 using a radar strapped to a jet. In addition, the jet was also equipped with a unique autopilot system to ensure consistency in its altitudes and courses as it passed over the areas over the years.
After comparing information from the various radar readings, the team detected changes at the millimeter level in the elevation of the ground at a pinpoint scale, a level of detail that was unable to be achieved in previous studies.
"Previously, if we wanted to measure subsidence, we'd have to go and observe particular points," said Joshua Kent from Louisiana State University and co-author of the study. "This is like capturing a photo of the subsidence."
The two areas with the most dramatic results were the industrial areas Michoud, located in New Orleans East, and Norco in St. Charles Parish. Areas around Michoud dropped by around 1.18 inches each year, while areas around Norco sank by almost 1.6 inches each year.
The data suggests that further study should be conducted into the problem to determine if industrial operations are contributing to it. One possibility is that they are sapping significant amounts of groundwater out of the region.
In terms of suburbs, results were less dramatic but still present, with most of New Orleans and Jefferson Parish sinking at around a quarter-inch each year. However, the reason behind the differences in sinking rates per region is still unclear.
"It's usually no one single thing," Kent said. "It's a combination of multiple factors. They all operate on their own scales and their own timeframe."
The results of the NASA study support the findings of previous studies and suggest that the new methods of measurement could provide more accurate assessments of subsidence for future studies.
The findings were published in the May 16 issue of the Journal of Geophysical Research: Solid Earth.
