Study Shows Delta Sinking More Slowly than Thought

July 21, 2006

Michael Strecker
Phone: (504) 865-5210

While erosion and wetland loss is a huge problem along Louisiana's coast, the basement 30 to 50 feet beneath much of the Mississippi Delta has been highly stable for the past 8,000 years with negligible subsidence rates, according to an article in the August issue of the Geological Society of America's journal Geology.

Studying sediment core samples, Torbjörn Törnqvist, an associate professor of earth and environmental sciences at Tulane University and lead author of the article, made detailed reconstructions of what sea levels were in different sections of the delta over the past 8,000 years. Törnqvist's study covered areas near New Iberia, Franklin, and Lutcher-Gramercy.

Törnqvist and his students are currently investigating sediments in New Orleans, including an area close to one of the levee breaches along the London Avenue Canal. If his findings are borne out in New Orleans, it could have major implications for post- Katrina rebuilding plans.

Recent research has suggested that the basement of the Mississippi Delta is subsiding by about half an inch a year. But Törnqvist's study shows subsidence rates that are at least ten times less. A stable basement could allow rebuilding in low-lying areas thought to be sinking too rapidly to justify reconstruction.

Tulane University, New Orleans, LA 70118 504-865-5000