Hearing about 100-, 500-, 1,000-year floods in Florida? Here’s what it means

Florida Gov. Ron DeSantis says state experienced ‘500-year flood’ after Hurricane Ian

Seminole County Emergency Management is beginning the task of assessing the full scope of damage done to the county by Ian.

In the aftermath of Hurricane Ian, Floridians are feeling the impact of the storm after high-speed winds and relentless rains left entire neighborhoods, cities and counties flooded.

Some state, county and city officials have even called the widespread destruction the result of 100-, 500- and 1,000-year floods.

But what does that mean?

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According to the Federal Emergency Management Agency, a 100-year flood event is any flood that has a 1% chance of being equaled or exceeded during any given year. Similarly, a 500-year flood event is any flood that has a 0.2% chance of happening during any given year and a 1,000-year flood event is any flood that has a 0.1% chance of happening during any given year.

Orange County Fire Rescue officials responded to Arden Villas Apartments near University Boulevard Thursday night to help evacuate about 200 residents to a sister facility in Altamonte Springs.

While FEMA said these floods don’t occur frequently, the term doesn’t indicate that a flood event of these proportions hits every 100, 500, or 1,000 years, but rather indicates the likelihood that they will hit. It’s much more common for an area to experience 1-,2-,5-, and 10-year flood events.

These measurements are used to indicate the number of feet “above flood level,” or “above the normal water surface level at which water begins going over the banks of a given watercourse,” to help people determine how badly they will be affected.

Florida Gov. Ron DeSantis held a news conference Thursday morning at the State Emergency Operations Center in Tallahassee to discuss the latest official outlook regarding what is now Tropical Storm Ian.

Florida Gov. Ron DeSantis on Thursday described Ian’s impact on the state as a 500-year flood event, hammering home how unlikely damage of this magnitude is and how much it affected residents.

While Ian initially made landfall in southwest Florida Wednesday, pummeling that area as a Category 4 hurricane, cities and counties across Central Florida also experienced record-breaking flood levels as the storm traveled across the state.

Hurricane Ian brought “unprecedented historic flooding” to Seminole County, with continued flash flood warnings on Thursday.

New Smyrna Beach on Friday referred to the flooding caused by Ian as “1,000-year rains,” saying the weather has caused widespread damage throughout the city.

The city said 18 to 24 inches of rain fell over a 24-hour period, prompting about 180 evacuations to emergency shelters.

In addition to the rain, Ian’s maximum gust of 95 mph and sustained winds toppled a large number of trees, disrupting power throughout the city.

“Our city is experiencing unprecedented flooding across every area,” Mayor Russ Owen said. “Many streets are impassable and there are hidden underwater dangers in previously safe areas. Venturing out for sightseeing purposes can place your life and our first responders’ lives in careless jeopardy. Do not go out. Stay home while we wait for water to recede and make assessments.”

The city also warned residents not to drive through standing water.

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About the Author:

Samantha started at WKMG-TV in September 2020. Before joining the News 6 team, Samantha was a political reporter for The Villages Daily Sun and has had freelance work featured in the Evansville Courier-Press and The Community Paper. When not writing, she enjoys travelling and performing improv comedy.