How did Hurricane Katrina affect the Gulf Coast around New Orleans?

Hurricane Katrina, which struck in August 2005, was a catastrophic tropical cyclone that caused immense devastation to the Gulf Coast, particularly in New Orleans. While the city was spared a direct hit from the storm's most intense winds, the levee system protecting the metropolitan area—much of which lies below sea level—failed under the pressure of heavy rain and a massive storm surge.12

The resulting flooding submerged approximately 80 percent of New Orleans by August 30, creating a severe humanitarian and public health crisis for residents who could not evacuate. The disaster caused over $125 billion in damage and led to a significant, long-term decline in the city's population. In the aftermath, the U.S. Army Corps of Engineers identified critical flaws in the flood-protection infrastructure, leading to extensive upgrades that have since bolstered the region's defenses. Beyond New Orleans, the storm surge devastated coastal communities in Mississippi, such as Gulfport and Biloxi, where surges reached as high as 28 feet.12