Ida v. Katrina in New Orleans: Fewer People, Better Levees, Smaller Storm Surge

Hurricane Ida and Hurricane Katrina in 2005 made landfall within 50 miles of one other and each carried 150 mph winds at one point, but the amount of death and destruction caused by the two storms was vastly different because of key differences.

CoreLogic compared the two hurricanes during a webinar on Thursday. The catastrophe modeler predicted that onshore insured losses from Ida will range from $14 billion to $21 billion, including losses to the National Flood Insurance Program. By comparison, Swiss Re said in a report last month that Katrina generated insured losses of $86 billion, accounting for inflation, and said damages would be far more extensive if the same storm were to follow the same path today.

“Katina hit only 50 miles to the east, but it was an important 50 miles because it hit a populated area of the Mississippi coastline where the surge and the winds were able to do an incredible amount of damage not only to New Orleans but the coastline of Mississippi and even Alabama,” said Shelly Yerkes, senior director of product manager for CoreLogic.

Yerkes explained that Ida came ashore in sparcely populated swampland. Grand Isle, a small barrier island town south of New Orleans, bore the brunt of the hurricane’s fury.

“Homes were taken down and used as battering rams so there are many homes on Grand Isle that are nothing but pilings left standing over open water and it left several feet of sand on the coast,” Yerkes said. “Now some properties are literally washed away and they’re sitting in open water, so Grand Isle is transformed, possibly forever.”

The New Orleans metropolitan area fared better, even though that may be lost on residents who were still grappling with power outages four days after the storm.

Katrina’s maximum sustained winds of 125 mph at landfall were weaker than Ida’s 150 mph peak, but Katrina had been a significant storm for days and reached the Category 5 level, with winds of at least 157 mph, for many hours before it struck. That gave more time for the wind to pile up waves and water, said David Smith, CoreLogic’s senior leader for science and analytics.

Katrina’s 25-foot storm surge breached the meager levees and flood walls that protected New Orleans from ocean waters, killing an estimated 1,400 people and flooding 80% of the city.

Ida’s storm surge height reached only eight feet, in part, because the storm rapidly intensified, giving less time for its strongest winds to build up. Ida was a tropical depression only three days before it struck and was a Category 2 storm only 12 hours before landfall, Smith said.

New Orleans is now protected by a 133-mile perimeter of levees and flood walls with heights reaching 30 feet in some locations, CoreLogic said. The levees were only five feet high when Katrina struck.

What’s more, Ida was a smaller storm than Katrina, with hurricane-force winds extending only 45 miles from the eye. Hurricane winds with Katrina, by contrast, extended 120 miles.

Ida’s storm clouds also fell over a significantly smaller city than the New Orleans that existed in Katrina’s time, Yerkes said. The 2005 hurricane damaged 70% of New Orlean’s housing stock, a total of 135,000 units. Only 30% of those homes were rebuilt. Yerkes said many of the home sites lied below sea level.

Yerkes said 500,000 people moved away from the New Orleans metropolitan area after Katrina. The urban area’s population even today is 75% of what it had been in 2005.

“There’s just less exposure in the New Orleans area,” she said.

And the exposure that does exist tends to be better built. Louisiana adopted stronger building codes in 2004, but only give parishes had adopted the stricter standards. Now, there is mandatory enforcement in all 65 parishes.

Homeowners in the New Orleans area are often more likely to have flood insurance. Tom Larsen, a principal for insurance solutions, said 50% of homeowners that suffered flood damage from Ida had flood insurance, an improvement since Katrina’s time. By comparison, he said only 30% of Houston-area homeowners who suffered damages from Hurricane Harvey in 2017 had flood insurance.

“Its very encouraging that we are seeing an increase in the amount of damage that is covered by insurance,” Larsen said.

After CoreLogic prepared its presentation, Hurricane Ida continued to wreak havoc. Remnants of the storm sparked tornadoes and dumped record rainfall on a vast urban area that included Philadelphia and New York City.

The flooding and wind that struck the Northeast will likely have an impact on auto insurers, in addition to property. CCC Intelligent Solutions said in an email that only a modest number of claims have been recorded in its automated system as of Thursday, but typically the bulk of claims won’t come in until two weeks after a storm event.

“As a point of reference, only 10% of claims following Hurricane Harvey were processed on behalf of CCC insurance customers in the days immediately following that storm,” said Public Relations Director Michelle Hellyar. “We anticipate the majority of auto claims from Hurricane Ida to be the result to wind damage to structures and vehicle total losses as a result of flooding.”

“CCC anticipates total loss claims in New York and New Jersey as a result of flooding will surpass claim counts from Louisiana and Mississippi based on photos of damage alone,” she said.

Smith said that reinsurers may recognize the flooding and wind damage in the Northeast as a separate event. He said reinsurance contracts often have an “hours clause” that defines the length of time that can be defined as a specific event. Some contracts create a 72-hour window while other common contracts give up to 168 hours (seven days) to define events as a single event, CoreLogic said.

About the photo: The remains of destroyed homes are seen in the aftermath of Hurricane Ida in Grand Isle, La., Tuesday, Aug. 31, 2021. (AP Photo/Gerald Herbert)