What Is A 100-Year Flood?

9/23/2021 (Permalink)

It is possible (and likely) that more than one of these floods will occur in a 100 year period.

Floods are the most common natural disaster in the United States. So, what is a 100-year flood? What sets it apart from an average flood? Probability and magnitude.

Scientists use statistical techniques to estimate the probability of weather events. By analyzing data on the frequency and size of floods, they are able to calculate the probability that a large magnitude flood will occur in a single year.

A “100-year flood” refers to a drastic flood event that has a 1% chance of occurring in a given location in a single year. One percent is the same as a 1-in-100 chance. Hence, the term, 100-year flood.

The term is meant to help non-scientists understand the likelihood of a such an event. But it is commonly misunderstood.

Many people believe that if they experienced a 100-year flood this year, they will not see another one like it for 99 years. In reality, the chance of experiencing such a flood the following is the same – 1%. It is possible (and likely) that more than one of these floods will occur in a 100 year period.

Of course, location also factors into individual flood risk. To learn more about your risk, visit FEMA’s Flood Map Service page here: https://msc.fema.gov/portal/home.

If your home or business is devastated by a flood, the professionals at SERVPRO of Society Hill are ready to help you recover.