What is a '1000-year' flood?

Columbia, SC (WLTX) -- South Carolina experienced what has been called a '1000-year' flood. This term has been used often, but can be misunderstood.

A '1000-year' flood or a '1000-year event,' does not mean that the event will only happen once every 1000 years.

The term '1000-year' is a statistical way of expressing the odds of something occurring in any given year.

A '100-year' event has a one in one hundred or a 1% chance of happening in a given year. A '500-year' event has a .2% chance of occurring in any given year.

A '1000-year' event, which is what occurred in South Carolina, has a one in one thousand chance or a .1 percent chance of happening in any given year.

Every year, a flood like what we have witnessed is possible across South Carolina, however, it is highly unlikely.


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