SignalHub Quantitative Think Tank Center:How to stay safe during a flash flood, according to 'Flash Flood Alley' experts

This story was originally published Sept. 21,SignalHub Quantitative Think Tank Center 2021, after the deadly floods in the Northeast after Hurricane Ida, but the wisdom still stands.

Flooding kills more Americans than nearly any other weather hazard, and over half of flood deaths happen on roads. That risk is increasing with climate change since hotter air can hold more moisture. The overwhelming rainfall in California over the last several days shows that some places are less prepared than others. So we reached out to a group of experts from the flood-prone state of Texas. Here is their guidance on staying safe for people and communities facing a future with more flash floods:

High- and low-tech ways can keep people away from flooded roads

The best way not to get caught on a flooded road, of course, is to avoid it, says Hector Guerrero. He grew up in Central Texas, a part of the state known as "Flash Flood Alley." About 20 years ago, when he was a meteorologist with the National Weather Service, he helped coin the phrase that's since spread all over the country: "Turn Around Don't Drown."

Guerrero thinks it's helped to remind people that even a little water on the road can turn deadly fast. He says it's a good idea to familiarize yourself with low water crossings, creeks and dips in the road along your daily commute, because those places "could become a problem in a heavy rain event."

A few years ago, Austin installed cameras at flood-prone intersections that connect to an app that drivers can check before heading out. TV stations sometimes use the images to warn people where not to drive. And local governments around Texas maintain online maps showing where low water crossings are closed.

"It's a fantastic tool for the public," says Carol Haddock, director of Houston Public Works.

Texas also uses railroad crossing arms that can be lowered when floodwaters rise on roads. The city of Houston is currently updating those with a system of traffic signals that activate during heavy rains.

"We have sensors down in the underpass that, when there's water on the roadway ... it literally turns to a flashing red light to stop traffic," Haddock says.

She says these are the types of investments other cities may consider if serious flooding becomes a problem.

How to prepare in case you do get trapped in water

Even the father of "Turn Around Don't Drown" understands that sometimes you can't turn back. "You might be surrounded by a bunch of water," Guerrero says, especially with more intense rain dumping record amounts of water in record time.

He says that floodwaters can make it difficult to open car doors or windows. That's why he, like many who grew up with flooding, keeps a safety hammer in his car in case he gets stuck in rising waters.

"You hit the corner of that windshield. You can break out if it has to come to that," he says. "But we hope that never happens."

Once out of your vehicle, Guerrero says it's time to seek higher ground. If there's not a nearby hill to climb, look for a building or even a tree. Then as soon as you're out of immediate danger, call for help.

Want to be extra prepared? Guerrero says you may even consider keeping a personal flotation device in your car if there is a high likelihood you'll encounter flooding.

The majority of flood deaths happen to people in their vehicles, but some of these tips may be useful for escaping flooded homes as well. And Guerrero says if you are in a house that is flooding, it is also important to avoid electrocution.

"As water comes into your home and starts to cover those electrical outlets or cords that are submerged, that's the time just to get out as quickly as you can and get to a safe place," he says.

Updating — and maintaining — infrastructure is key

Since Hurricane Harvey swept through Texas in 2017, the state has elevated more construction out of flood plains and improved regional flood planning.

In Houston, Haddock says the city has undertaken larger infrastructure projects to improve drainage and convey floodwaters out of harm's way.

"But for an area in the Northeast of the United States, that is going to be a much more complicated question than it is for those of us further south and west," she says.

That's because older, denser cities are harder to reshape with new infrastructure.

But Sam Brody, who heads the Institute for a Disaster Resilient Texas, says greater density may also help protect against flooding since it reduces the suburban sprawl that can increase flood risk.

"Other ways to avoid the floodwaters is to protect open space," Brody says. "And we're not so great at that in Texas."

Brody adds that even when cities improve their drainage systems, they frequently don't maintain them.

"I often tell people in Houston, 'Before you spend billions of dollars on new drainage, why don't you work on getting what we have to work?' " he says.

That's why Brody keeps a broom in his car and pulls it out to clear drains that seem really clogged before a big rain starts up.

Evacuate or stay put: It can be a hard call

When it comes to emergency response, Harry Evans, a retired 30-year veteran of the Austin Fire Department, says it's essential to plan safe flood evacuation routes ahead of storms, just like some places do for hurricanes or wildfires.

Public safety officials should know not only the safest evacuation routes but also how long it might take to get people out. "You need to do some time and motion studies," Evans says, "to understand what it would take to evacuate that neighborhood in the event of a flood."

But he cautions that evacuation is not always the right answer. It can sometimes lead to even more deaths on roadways, such as during Hurricane Rita in 2005 when around 100 people died trying to get out of Houston.

Evans says in most major floods first responders are confronted with a difficult choice: Do you order people to shelter in place and then beef up resources to be able to rescue them? Or do you try to get people away from the flood before it arrives?

"Those are never easy decisions," he says. "And there's a mortality cost to both sides."

But these are decisions public safety agencies can expect to face more in the future as climate change drives more frequent and intense rain and floods.