It's been ten years since Hurricane Katrina made landfall in the western US. Now NASA and the US Geological Survey (USGS) have released detailed maps showing how radically the hurricane changed not only neighbor- and livelihoods, but also the geography of New Orleans itself.
The maps in question are part of a larger study recently published by the USGS which compare images of wetlands surrounding Delacroix, a fishing town to the southeast of New Orleans, before and after Hurricane Katrina. These results were also compared pixel-pixel with a series of Landsat and commercial satellite images taken following Gustav, another hurricane that struck in 2008.
Predictably, researchers concluded that that Katrina's extreme winds, long duration (20 hours), and major storm surge (up to five meters) did serious, lasting damage to Delacroix's marshes, with landmarks such as Lake Lery and Petit Lake becoming significantly enlarged. New water channels and widened canals were also formed, consequentially draining large swaths of wetland essential to New Orleans' local wildlife. Gustav's visit, they found, only made sure those 'geological scars' stay permanent. (Scroll to read on...)
Perhaps most shocking of all is the revelation that Katrina and Gustav seem to have built more solid land in the region.
"In the 2015 image, for instance... the expansion near Big Mar and along some of the other new ponds and channels west of Lake Lery," NASA's Earth Observatory noted. "In total, 3.3 percent of pixels were converted from water before Katrina to land afterward."
Thankfully, what marsh remains appears to be recovering, with 2015's vegetation returning to normal and healthy colors.
"If Delacroix continues to dodge hurricanes, we can expect to see the extent of aquatic vegetation increase even if we don't see the full reestablishment of healthy marsh in all the areas that had it before Katrina," Monica Palaseanu-Lovejoy, one of the US Geological Survey scientists, said in a statement. (Scroll to read on...)
[Credit: NASA Goddard Space Flight Center/Bill Putman]
Still dodging hurricanes for much longer might be easier said than done. NASA and the National Hurricane Center have noted that this decade-long period, where no major hurricane has stuck North America, is exceptionally rare. Specifically, a dry-spell like this is likely to occur only once every 177 years. This lack of major storms could also be what has allowed Katrina's 'scars' to stay.
"The last nine hurricane seasons were not weak - storms just didn't hit the US," NASA researcher Timothy Hall added in a statement. "It seems to be an accident of... random good luck." (Scroll to read on...)
[Credit: NASA's Goddard Space Flight Center ]
However, the expert is willing to admit that other factors may be at work as well. With climate change fundamentally shifting how and when extreme weather occurs around the globe, some have argued that warming waters in the north may be directly leading to more, or even fewer hurricane storms. Hall explained that it all remains a very inexact science.
"Hurricanes respond in complicated ways to their environment," he said. "It's one of the areas of climate change research where reasonable people can still disagree."
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