Louisiana is officially sinking … albeit slowly.
It has been 29 years since the National Geodetic Survey measured the state’s subsidence. After completing four absolute gravity observations this past year, with the help of LSU’s Center for Geoinformatics, or C4G, the NGS’s most recent findings show the Louisiana’s change in elevation, LSU announced today.
“This is the second observation NGS has performed in Louisiana, with the first one having taken place at the University of New Orleans in 1989,” LSU Chief of Geodesy Cliff Mugnier said. “Since then, the four additional observations through 2018 show a cumulative apparent subsidence of 147 mm in 29 years, which is 5 mm a year.”
Translation: The state sank about 5.7 inches in elevation over the decades.
A closer look at the elevation changes over the past 30 years shows Baton Rouge, Lafayette, Oakdale, Hammond and Shreveport have remained virtually unchanged, while other areas of the state weren’t so lucky. Alexandria, Old River, Lake Charles, Boothville and Ruston all sank. Some areas actually gained ground, such as Thibodaux, Sicily Island, Rayville, and Natchitoches, although each of those gained less than one inch of elevation.
LSU C4G now has a three-person, permanent gravity survey crew traveling around the state to collect information about elevation and tides for the state. Read the full announcement from LSU.