What to do if caught in a Flash Flood

Nearly half of all flood-related fatalities in the U.S. involve vehicles. Most of these deaths happen when people drive into flooded highway dips or low drainage areas. Saving your life can be as easy as turning your car around when you see water on the road. Never try to drive through flooded roadways, and do NOT drive around barricades at Low Water Crossings.

Even in relatively shallow water, tires can act as flotation devices lifting up even big vehicles and sending them downstream. Two feet of water is enough to float a 3,000-pound car. Also, keep in mind that water covering roadways may hide washed-out bridges or gouged-out roadbeds. If you try to drive across, you may not be driving on a road.

Even on a clear day, flash flooding can occur due to rain happening several miles upstream. Few people realize how fast water can rise in a small stream to flood a Low Water Crossing area. Despite your best efforts, you could find yourself in a flash flood situation. Whether walking or driving, here are some steps you should take:

  • If you are in a low-lying area during a flood, get to higher ground quickly. Avoid canyons, washes or ditches that can channel swift water.
  • Do not attempt to cross flooded roads or streams on foot. The water may be flowing more rapidly than it appears, and it can take as little as six inches of water to knock an adult off their feet.
  • Be especially cautious at night when it is harder to see flood dangers.
  • Never allow children to play near ditches and storm drains.
  • If your vehicle is suddenly caught in rising water, leave it immediately and seek higher ground.
  • If your car is swept into the water and submerged, DON'T PANIC! Stay calm and wait for the vehicle to fill with water. Once the vehicle is full, the doors will be able to open. Hold your breath and swim to the surface.
  • If you are swept into fast moving floodwater outside of your car, point your feet downstream. Always go over obstacles, never try to go under.
  • If you are stranded on something above the floodwater, such as a tree or building, stay put and wait for rescue. Do not enter the floodwater.
  • When help arrives, stay calm and follow the directions of the rescue team.

SAFD Special Operations Teams

 

Fluid Dynamics
  • Water weighs about 62.4 pounds per cubic foot and typically flows downstream at 6 to 12 miles an hour.
  • When a vehicle stalls in the water, the water's momentum is transferred to the car. For each foot the water rises, 500 pounds of lateral force are applied to the car.
  • For each foot the water rises up the side of the car, the car displaces 1,500 pounds of water. In effect, the car weighs 1,500 pounds less for each foot the water rises!
  • Most cars will float in just two feet of water!