One Chart Shows Just How Bad The Flooding Is In Colorado

Heavy rain and flash floods in Colorado have killed at least four, while thousands of others are being evacuated from their homes.

In Boulder up to 10 inches of rain fell on the city in one night, flooding the area with around 4.5 billion gallons of water, according to the Denver Post.

The chart below shows Boulder Creek's flow rate over the last month, peaking at around 4,500 cubic feet per second (cfs) in the last couple of days. That is 45 times greater than the typical flow rate of 100 to 300 cfs. One cubic foot per second is equal to roughly 7.5 gallons of water per second.

A U.S. Geological Survey spokesman told the Post that this is a "100-year-flood," meaning there is only a 1 in 100 chance that a flood of this magnitude will happen each year (it does not mean that they occur at 100-year intervals).