Is the US Ready for the Next Hurricane Katrina?

By Larry Greenemeier

August 26,2015; 10:49AM,EDT

Credit: Courtesy of the National Oceanic and Atmospheric Administration (NOAA), via Wikimedia Commons
A decade ago Hurricane Katrina terrorized the Gulf Coast. What began as a tropical depression over the Bahamas quickly spun up into an unstoppable beast of wind and water that laid waste to parts of Louisiana, Mississippi and Alabama. New Orleans and its surrounding communities endured hours of surging water that quickly toppled inadequate defenses and flooded the region under more than three meters of water in some places. More than 1,800 people died during the storm and its aftermath, which left an estimated 600,000 families homeless.
The failure of New Orleans's flood protection system was epic. The city, founded nearly 300 years ago, was built on low-lying marshland along the Mississippi River. After Hurricane Betsy battered New Orleans in September 1965 the U.S. Army Corps of Engineers began to build a network of levees and floodwalls -- also called I-walls -- to protect the Big Easy and adjacent parishes (counties). Unfortunately, planners never anticipated a storm surge of Katrina's magnitude.
During and after that tempest billions of liters of water from the Gulf of Mexico, Lake Borgne and Lake Pontchartrain overwhelmed or outright destroyed the city's flood protections. Storm water pouring over the concrete floodwalls in many places eroded away the soil on the other side that gave those structures their footing. As the bottom of the I-shaped walls was laid bare, the water pressure behind them toppled or pushed them aside. Meanwhile many of the pump stations installed to evacuate water from canals behind certain floodwalls were rendered useless, drowned by in the very water they were supposed to be siphoning away, according to a 2007 American Society of Civil Engineers (ASCE) report aptly titled "What Went Wrong and Why."
The New Orleans hurricane protection system's main shortcoming: It wasn't actually a system. Instead, it was constructed as individual pieces based on bad math. "Levee builders used an incorrect datum to measure levee elevations -- resulting in many levees not being built high enough," according to the ASCE report. Some were nearly a meter lower than the intended design elevation, the report states. Add to that a poorly coordinated and executed disaster response plan -- at both the national and local levels -- and the stage was set for Katrina's destructive rampage.
Surely, the U.S. is ready for the next Katrina or Hurricane Sandy, right? To find out Scientific American spoke with Robert Traver, a civil engineering professor at Villanova University and co-author of the ASCE report. Traver surveyed Katrina's destruction firsthand after the storm, serving as a member of the ASCE External Review Panel that helped the Corps investigate the hurricane protection system's catastrophic breakdown.
[An edited transcript of the interview follows.]
How did you get involved in the U.S. Army of Corps of Engineer's investigation of the New Orleans hurricane protection system after Katrina?
A couple of weeks after Katrina the Corps contracted the American Society of Civil Engineers to provide quality control for the [Corps's] study of the storm's aftermath. We were there to make sure the right questions were being asked and the right processes were being used to understand what had happened.
The ASCE published a report with lessons learned after your post-Katrina work. What were the most important takeaways?
Three were especially important: The first is that there wasn't an overall systems approach to the region's hurricane protection system. One of the first questions I asked was: What was the plan for when water overtopped the levees? There wasn't one. In addition, the water pumping stations were designed for heavy rainfall, not for hurricanes. They didn't have alternate power sources or safe housing for the people working there. And in at least one of the levees that caused flooding, there were actually areas where the levee was intentionally built lower to the ground in order to protect the pump stations by relieving some of the water pressure. There were also inconsistencies in how the levees and pump stations worked together. That's probably because the Army Corps of Engineers had built the levees while the city was in charge of the pump stations. I don't know how to say it nicely, but that [lack of coordination] was just incredible to me.
What were the other key observations?
The second important lesson to be learned is the great failure of communication in terms of making sure people understood how risky it is to live in New Orleans. Before Katrina the residents didn't seem to fully understand this, even though the information was available to people making the decisions down there. The Corps pretty much described what would happen in the event of a major storm every year when they put out their request to Congress for funding. And the ASCE, in its Civil Engineering magazine, had published an article two years before Katrina that talked about exactly what would happen during a major storm. Still, people felt safe behind the levees so they wouldn't leave.
The third lesson-and this applied to Sandy on the east coast a few years later, too-is that you need an analysis of the risk and consequences of failure. If you've never taken a close look at what would happen if water overtops your storm protections, then you won't know what's needed in terms of an evacuation plan and other emergency planning.
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