Why is floodwater so dangerous?

  • Mary Caldwell
  • For the AJC
3:07 p.m Friday, Sept. 8, 2017 Weather
CHRISTMAS EVE FLOODING--Localized flooding closes DeKalb County's Chamblee Dunwoody Road near the Chamblee Antiques Market after more than two inches of rain fell across the metro area Wednesday, Dec. 24, 2014, in Chamblee, Ga. David Tulis/AJC Special

Flooding may not always receive the attention that other weather-related disasters, such as tornadoes, receive, but it can be deadly. In fact, more people are killed in the U.S. by flooding each year than are killed by tornadoes, hurricanes or lightning, according to The National Severe Storms Laboratory. Flooding causes more weather-related deaths each year in the U.S. than anything except heat. It's the most common weather-related disaster, and it can occur in any state.

Floods can occur when dams break or when too much snow melts too quickly, but most often occur because of heavy rains. This can cause storm drains to become overwhelmed and result in flooding.

Flash floods occur when creeks that are normally dry fill up and other creeks overflow. This can happen suddenly, particularly in densely populated areas.

Normally, the ground absorbs rain, but when an area has lots of highways, driveways and buildings, the potential for flash flooding rises.

Floodwater is dangerous when you're driving because there's no way to judge how deep or rapid the water is until it's too late and you've put yourself and any passengers in danger. This is even more true when you're driving in heavy rain or at night when your vision is limited.

News | WFTV

Hurricane Matthew could bring flooding to Central Florida. Here's why you shouldn't try your luck by driving through standing water.

When your vehicle is in floodwater, you may think that it's too heavy to float, but that's not the case. The force of the moving water can cause your vehicle to be pushed sideways in a flooded road, according to the National Oceanic and Atmospheric Administration (NOAA). This can make driving even a large vehicle into floodwater extremely dangerous, because it may flip on its side or roll over completely, giving you just seconds to escape.

In addition, a flooded road can become washed out as a result of rapidly flowing water, further increasing the danger.

Over half of all flood-related drownings happen when people drive vehicles into floodwater. It only takes 12 inches of rushing water to carry away a small car. Two feet of rushing water can carry away most vehicles.

For the same reasons, walking into floodwater is dangerous. Just six inches of rushing water can knock an adult over – and it takes even less to knock over a child.

Floodwater can also expose a person to injury or to illness from infectious diseases (caused by sewage overflow and other contaminants), chemical wastes and sharp objects, according to the Centers for Disease Control and Prevention. You may also encounter downed power lines due to high winds and other hazards such as snakes.

View full experience