Hurricane Ida made landfall on August 29, the 16th anniversary of Hurricane Katrina. The powerful Category 4 storm battered the state with strong winds, heavy rain, and storm surges. Hurricane Ida caused mass power outages, while wrecking homes and businesses, damaging roads and bridges, and causing 26 deaths in the state.
While it may not be unexpected, the most surprising thing to happen was that Ida was so powerful it actually reshaped the landscape of the southern coast of the state.
Five days after catastrophic storm surge, winds, and downpours pummeled the Mississippi River Delta, the Operational Land Imager (OLI) on Landsat 8 acquired imagery of the storm-damaged region.
The images taken five days after the storm showed many water bodies were still discolored by sediment stirred up by rain and floods. Floodwaters still swamped areas along many rivers, coasts, and lakes. Damaged or missing marsh vegetation left large patches of open water, especially in parts of the Lafourche, Jefferson, and Plaquemines parishes.
“A combination of flooding, erosion, and defoliation during Ida likely created many of the new patches of open water visible in the Landsat image,” explained Marc Simard, the principal investigator for NASA’s Delta-X mission, a field campaign to the Mississippi River Delta that was conducting research on sediment and marsh dynamics when Ida approached.
The Delta-X mission is planning on resuming flights using plane-based radar later this month to determine how much of the damage and loss of vegetation may be permanent in this region already vulnerable to the steady encroachment of the Atlantic Ocean.
Gizmodo points out that the levees, upstream dams, and rising sea levels due to human-instigated climate change are causing wetland regions to slowly shrink and even vanish.
Other human activities, such as the pumping of groundwater and oil, are also contributing to this process, as is the natural sinking and settling of new delta sediment, according to NASA’s Earth Observatory.
Following are two images that show an altered river delta. A Landsat 8 satellite photo shows the New Orleans region as it was on September 19, 2015, and then as it looked on September 3, 2021, five days after Ida hit the region.
Image: Joshua Stevens/Landsat/U.S. Geological Survey
Image: Joshua Stevens/Landsat/U.S. Geological Survey
The Delta-X team plans to track salinity levels to see if saltwater marshes might take over freshwater marshes. They’re also hoping for an influx of river sediment, which could replenish eroded coastal areas and give plants a place to live.
Simard says, “Our hope is that the models being developed by Delta-X scientists will provide a realistic insight into the vulnerability and resilience of wetlands in this region in the long-term.”
“Realistic” is the keyword. The Mississippi Delta has been under assault from the environment and human-induced climate change for some time now, and it is possible it will never come back to what it was. And of course, we are still in the middle of the Atlantic Hurricane season, too.
