Louisiana is officially sinking. 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 (C4G), the NGS’s most recent findings show the state’s change in elevation.
“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 (at the University of New Orleans) show a cumulative apparent subsidence of 147 mm in 29 years, which is 5 mm a year.”
A closer look at the elevation changes over the last three decades shows that Baton Rouge, Lafayette, Oakdale, Hammond and Shreveport have remained virtually unchanged while other areas weren’t so lucky. Alexandria has subsided -49 mm, Old River -34 mm, Lake Charles -16 mm, Boothville -13 mm, and Ruston -9 mm. Some areas actually gained ground, such as Thibodaux +7 mm, Sicily Island +8 mm, Rayville +13 mm, and Natchitoches +17 mm.
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