Editor’s Note: This article originally appeared on CBSDenver.com in 2014. The facts remain applicable in 2015.
DENVER (CBS4) – Flood and wildfire season is just around the corner, but in Colorado, a natural disaster can strike during any month of the year.
Gov. John Hickenlooper has declared this week Colorado Flood Safety and Wildfire Awareness Week.
Today’s message is about different types of flooding.
All of Colorado’s 64 counties have areas that are prone to flooding.
More than a quarter million people, roughly 65 thousand homes and 15 thousand businesses are located directly within a floodplain.
Since 1900, there have been over 400 people killed by flooding in our state.
A flash flood is a dangerous, sudden rise of water along a river or creek, in a canyon or over a stretch of land that is normally dry.
They’re most often caused by heavy rain, but can also be a result of a dam break or a clog in the flow of water along a stream, such as an ice jam. Flash floods are also very common in and around burn scars after a wildfire.
Flash floods typically catch people off guard because they can happen within a few minutes to a few hours after the event that caused it. They are challenging to forecast because they happen so fast.
Areas experiencing drought conditions are also prone to flash floods.
River flooding is different from a flash flood because it can be predicted, sometimes up to several days in advance. They are usually caused by heavy rain or rapid snow melt.
In the major flood event of September 2013, we saw both types of flooding in Colorado. It started as a flash flood in the foothills and along Interstate 25, then turned into river flooding as waters traveled along Front Range waterways and into the South Platte River in northeast Colorado.
Most flood fatalities are caused by flash floods, and nearly half of all deaths are vehicle related. A hidden danger when attempting to cross a flooded road is not knowing if the pavement beneath the water has been washed away.
Most vehicles can be carried by a foot or two of swiftly moving water. The force of water is so powerful that by the time a driver realizes they have made a mistake by attempting to cross a flooded road, it’s usually too late.
WATCH VS. WARNING
The National Weather Service will issue flood or flash flood watches and warnings when the threat is present. A watch means to pay attention to today’s forecast because conditions are right to create the danger, and things could rapidly change.
A warning means the danger is present or will occur very shortly, and action to protect your life and property should be taken.