New research provides a more accurate picture of future flood risks along important parts of the Gulf Coast that have been subtly sinking, or subsiding, for years, largely undetected.
The project, led by researchers from The University of Texas at Austin, mapped nearly 51,000 square miles of the Texas and Louisiana Gulf Coast using advanced satellite technology. The researchers found widespread land subsidence that was previously too difficult to detect. Causes of the subsidence include oil and gas production, ground water pumping and wetland degradation.
"Though the subsidence was subtle, on the scale of centimeters and millimeters per year, the impact is significant", said project lead Jingyi "Ann" Chen, associate professor in the Cockrell School of Engineering's Department of Aerospace Engineering and Engineering Mechanics and the Center for Space Research. "These topographical changes, poorly measured until now, can substantially increase the havoc wrought by flooding from hurricanes and other major storms on communities across the Gulf Coast."
The research, published in Journal of Geophysical Research: Earth Surface comes at the tail end of a major hurricane season that has devastated Florida and the Eastern seaboard. The resulting storm surge flooded cities throughout these areas.
This new research gives a more complete picture of the potential flooding impacts of hurricanes and other storms. The study utilized a new InSAR (Interferometric Synthetic Aperture Radar) processing algorithm to accurately measure subtle land subsidence previously undetected by traditional GPS and tide gauge stations. These complex regions had previously been challenging to analyze because of dense vegetation cover, but the team’s new InSAR algorithm was able to overcome this issue.
By integrating InSAR data into storm surge models, the study found that traditional flood mapping methods, which rely solely on topography, often underestimate flood risks. The new models predict more severe flooding due to the combined effects of land subsidence and sea level rise.
The study spotlights several areas at heightened risk of flooding, including New Orleans, and the northwest and southeast suburbs and exurbs of Houston.
"All of these areas face significantly higher future flood risk than previously known, not just because of rising sea level but also sinking land," said Ke Wang, first author on the project and a former student in Chen's lab who received his Ph.D. in 2023. "It's important that policymakers, urban planners, and community leaders are informed by these satellite measurements, and adjust planning and disaster preparedness efforts accordingly."
The research was funded by NASA and the National Science Foundation. The full team includes aerospace engineering faculty members Srinivas Bettadpur and Clint Dawson, Eirik Valseth of the Oden Institute, Gordon Wells of the Center for Space Research and Cathleen E. Jones of NASA Jet Propulsion Laboratory.
