Flowing Water Is More Powerful Than You May Think

Yahoo

a day ago

Flooding may not inspire the same fascination and fear as tornadoes or hurricanes, but you shouldn't underestimate its power.
From 2015-2024, flooding claimed an average of 113 lives per year in the U.S., according to National Weather Service statistics. This makes flooding the second-deadliest type of weather for the U.S., behind heat.
Let's lay out some impressive facts about floodwater.
Water flowing at just over 6 mph has the equivalent force per unit area as air blowing at EF5 tornado wind speeds. That means that at just 4 mph, flowing water produces a force strong enough to move boulders that are five feet in diameter.
Water moving at 25 mph has the force equivalent of wind blowing 790 mph, faster than the speed of sound. Floodwaters are thought to reach peak forward speeds of up to 67 mph. The fastest floodwaters are on steep terrain, in relatively smooth rock ravines or concrete channels.
Before deciding to drive through standing water, consider this: nearly half of all flash-flood related deaths involve cars and trucks. Six inches of water will reach the bottom of most passenger cars, causing loss of control and potential stalling.
According to the U.S. Geological Survey, water one foot deep typically exerts 500 pounds of lateral force, which could easily tip a vehicle on its side or flip it over. Two feet of rushing water will carry away most vehicles, including SUVs and pickups. The vertical buoyancy force of about 1,500 pounds per foot of water lifts the vehicle, while a lateral force of 1,000 pounds (or more if water is flowing faster) pushes it downstream. Once your vehicle becomes buoyant, it can be swept away, tipped on its side or flipped over, giving you only seconds to escape.
Never drive into floodwaters of unknown depth and never drive around barriers warning you of a flooded road ahead. You may not know if the road has been washed out and may underestimate the speed of the floodwater. As the National Weather Service advises, "Turn around, don't drown!"
If you slip and fall face-first in floodwaters, you might drown before you regain consciousness. Babies and small children are very vulnerable; just as they would be in a bathtub. Water levels in flash floods can rise one foot in five minutes. In some cases, for instance, in a canyon, near-instantaneous rises of 10-30 feet or more may accompany walls of water rushing downstream.
With all this in mind, if you live, camp or hike near a river, creek, or stream, particularly in hilly or mountainous terrain, you should consider evacuating to higher ground upon the issuance of a flash flood warning.
In general, awareness of the weather situation can save your life in a flash flood.
Act quickly once you receive a warning. Knowing how to quickly get to higher ground if you're in a flood-prone area could save your life.
Miriam Guthrie graduated from the Georgia Institute of Technology with an undergraduate degree in Atmospheric and Oceanic Sciences and is now a meteorology intern with weather.com before returning to school for her masters.