Some similarities with Isaac, Katrina

AUSTIN (KXAN) - The landfall of Hurricane Isaac is bringing back some terrible memories for people on the Gulf Coast.

Seven years ago to the day, Hurricane Katrina was devastating the city of New Orleans, becoming the third-deadliest hurricane in American history.

Now there are some important differences between these storms, but also some striking similarities.

Hurricane Katrina tracked just to the east of New Orleans, putting it on the less-dangerous, west side of the storm.

Katrina still managed to bring the New Orleans area 8-10 inches of rain, gusts of wind up to 100 miles per hour, and a storm surge of 14 feet. The storm moved over the city fairly quickly though – at 16 miles per hour.

Weaker, but still dangerous

Isaac has been a weaker storm, but the track is further west than that of Katrina – putting New Orleans on the more dangerous, east side of the storm.

Isaac has brought New Orleans more than 17” of rain so far, gusts of wind up to 83 miles per hour, and a storm surge of 12 feet – an amount more characteristic of a much stronger storm.

What makes this storm potentially just as dangerous as Katrina is the large size and the incredibly slow movement – current motion is at just 6 mph. If Isaac were moving from Austin to Dallas, it would take 33 hours to make the trip.dy

Isaac’s dangers are only half over – our attention will now turn to freshwater flooding from the incredible rainfall amounts. Many areas have received over 17”, and it’s still raining. To put that number in perspective, that’s more rain than Austin got in 12 months during the worst part of the drought.

The President of Plaquemines Parish, southeast of New Orleans, says flooding there is even worse than Katrina. But that levee is not part of the upgraded system in New Orleans. So far, the new system does seem to be protecting the city well.

A word or two about levees

Meanwhile, the reason we talk so much about the flood protection system around New Orleans is because almost half of the city is below sea level – in some areas, by as much as seven feet.

A network of wetlands and barrier islands on the coastline helps naturally reduce storm surge and buffer the city from hurricanes – but recently, human interference has destroyed some 2,000 square miles of coastline.

This makes New Orleans even more vulnerable to a storm like Isaac.

The Army Corps of Engineers recently completed a beefed-up levee and pump system costing over 14-billion dollars. This pump system is the largest in the world – capable of filling the Superdome stadium all the way to the top in just 7 minutes.

So far, the system appears to be working well. The strengthened levees have held in the city, and the pumps have been able to keep street flooding to a minimum, even though the area has gotten more than 17 inches of rain.

David Yeomans earned his Master's of Science from the University of Miami specializing in hurricane research. He was a guest scientist aboard the NOAA Hurricane Hunter aircraft.