Can we withstand another Katrina? Or worse?

Gustav was no Katrina, but on Monday the hurricane put New Orleans levees to their first serious test since Katrina flooded the city three years ago.

Anticipating a repeat of the 2005 disaster that killed over a thousand people, the city authorities evacuated almost the entire population.

But it wasn’t the most demanding of tests. Though wind-churned waves splashed over the levees, New Orleans suffered only minor flooding, and officials say evacuees may begin returning by mid-week.

In part, Gustav’s fading strength explains the lack of real damage. While Katrina peaked at Category 5 out at sea and made landfall as a still-powerful Category 3 hurricane, Gustav had faded from Category 4 to Category 2 by landfall on Monday.

But Gustav’s path was more critical. Katrina’s centre passed east of New Orleans, so its storm surge pushed Lake Pontchartrain southwards, flooding the city. Gustav, though, passed to the south and west, at a greater distance, and didn’t strongly affect the lake.
‘Hurricane fatigue’

Good news for the city authorities is that post-Katrina upgrades to flood walls did mitigate Gustav’s impact.

Katrina’s waters overtopped the walls and scoured out their bases, causing breaches. But, although Gustav’s waters did slop over the western flood wall of the city’s Industrial Canal, they fell on concrete pads that prevented scouring.

The storm made landfall in Terrebonne Parish, south of New Orleans, and moved northwest. Local newspapers reported widespread damage but not devastation. The storm also hit Port Fourchon, a hub for oil and gas drilling in the Gulf of Mexico, but that facility is built to withstand big storms, says Joseph Kelley, a coastal geologist at the University of Maine.

State officials estimated that 1.9 million people – about 95% of residents – evacuated the area before the storm hit, a big improvement over Katrina.

Kelley praised city officials for a plan that successfully evacuated residents without cars. But with Gustav failing to live up to expectations of devastation, he says, “you’re going to get evacuation fatigue,” and fewer people will leave the city as memories of Katrina fade.

via Newscientist