The storm’s remnants dumped stunning amounts of rain across the East Coast. But it wasn’t just the downpour that made the Ida’s aftermath so deadly. Experts say there were several factors that compounded and led to the devastation and high death toll.
People tend to underestimate flood warnings
The grim predictions, which came several days in advance, gave residents in the state’s most vulnerable communities — including areas outside Louisiana’s flood protection system — time to evacuate and seek higher ground.
Meteorologists similarly knew what was coming for the Northeast — and warned about the potential for major flooding.
But in severe weather events, it’s usually the threat of winds — not water — that pushes people to flee, CNN meteorologist Taylor Ward said.
“This is despite the fact that water is the number one killer in a hurricane — not winds,” Ward said. “In general, large numbers of people don’t evacuate from flash flooding. It could be that people have more fear or a hurricane than a flood, or believe they are more used to be being in flood watches and don’t need to leave.”
“We’re going to have to be much more aggressive with these tools,” de Blasio told CNN.
“It’s so hard to convey the threat of the remnants of a hurricane,” Dr. Craig Colten, professor emeritus of geography at Louisiana State University, told CNN. “We tend to really diminish the threat. But some of the worst flooding in recent decades has been inland flooding, or flooding from remnant storms.”
When storms are downgraded, people tend to relax and don’t pay as close attention, Colten said, which can make it difficult for officials to convey the dangers of approaching severe weather and convince residents that they should evacuate or take certain precautions.
“It’s hard to capture people’s attention in the same way when you’re talking about the remnants of a (storm). It’s now just a tropical depression, it’s no longer a hurricane. People aren’t going to leave a ground-level apartment.”
Since the amount of rain and flooding that parts of the Northeast saw was largely unprecedented, many people didn’t understand or underestimated what its effects would be, said Ward.
Infrastructure plays a critical role
Places like New York City are also not built to handle that kind of water.
“There are very few basements in Louisiana, very few people live below, or even have a part of their house below the land surface,” Colten said. “Architecture and the local high water table — which makes people not want to build basements and the fact that simply most houses are elevated, even with the same kind of rapid flooding that happened in New York, if that had occurred in Louisiana, you wouldn’t have seen the fatalities.”
De Blasio said Tuesday there are at least 50,000 illegal basement apartments across the city, with a total of at least 100,000 people living in them.
Colten said climate change means that severe weather events like the one that unfolded last week in the Northeast will continue to happen, and government leaders will have to adapt their current practices in order to ensure the public’s safety. “We need to make sure these illegal basement apartments are made safe,” he said.
Heavy rain came over a densely populated area
But it’s not just the infrastructure that didn’t help. The heavy rain came down — quickly — on one of the most densely populated areas in the US, which experts say also factored into the high death toll following the storm.
“The number of people and population density factored in hugely,” Colten said. “You’ve got 8 million plus people in New York City alone. Louisiana has four-and-a-half million people statewide, maybe a million in the exposed area. So, far fewer people were exposed to damage here.”
That’s also why evacuating places like New York City would be so much harder, he added.