World of Change: Atchafalaya Bay

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Although much of the Louisiana coastline is eroding, new land is forming in the Atchafalaya Bay, building up the deltas at the mouths of the Wax Lake Outlet and the Atchafalaya River. 

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory (
Story adapted from Image of the Day post:

  • Image of Atchafalaya Bay (2016), Operational Land Imager, Landsat 8
  • Photo of Atchafalaya Delta with channels (2016), Louisiana Sea Grant College Program
  • Photo of Bateman Island (2016), Louisiana Sea Grant College Program
  • Slideshow of images of Atchafalaya Bay from 1984 to 2017, Landsat 8
  • Written by Kathryn Porter

Text, World of Change. A globe spins in the background.
Text, Growing deltas in Atchafalaya Bay.
Atchafalaya Bay, Louisiana, United States. World of Change, 1984-2017. Picture of the area from Operational Land Imager, Landsat 8, 2016. Text, Although much of the Lousiana coastline is eroding, there are places where new land is forming. In the Atchafalaya Bay, about 85 miles southwest of New Orleans, sediment is being deposited, building up the deltas at the mouths of the Wax Lake Outlet and the Atchafalaya River. The bay is labeled at bottom left. The Wax Lake outlet points to the root-shaped portion at center, and the Atchafalaya River empties out into the bay to its east and south. Text, Geologists first noticed mud building up in Atchafalaya Bay in the 1950s. New land first appeared above the water line after a severe flood in 1973. Since then, both deltas have grown considerably. The rate of growth changes depending on the timing of major floods, which deposit sediment, and hurricanes, which cause erosion. Photo of the Atchafalaya Delta, Louisiana Sea Grant College Program, 2016. Text, Vegetation growth helps maintain new land by stabilizing sediment and preventing erosion. Photo of Bateman Island, Louisiana Sea Grant College Program, 2016. Text, This series of Landsat images documents the growth of the two deltas between 1984 and 2017. In these images, which show a combination of infrared and bisible light, water appears dark blue, vegetation is green, and bare ground is pink. The Wax Lake Outlet and Atchafalaya River at top center and right, respectively. What appears to be an island with pink portions is at the southwest end of the river in 1984. As years tick by at left, the areas around the outlets become root-like, stretching out into the bay. By 2017, they are as bright and vibrant as the vegetation had been on the original landmass.
Text, Change. Side-by-side comparison of November, 1984, and October, 2017.