An Irma Reminder: We Need Better Floodplain Mapping

by | Sep 11, 2018

When Hurricane Irma came ashore a year ago, most residents feared the massive winds.

But when the storm passed and people started assessing the damage, it was the standing water around – and sometimes in – their homes that was the bigger threat. Many residents in Southwest Florida can still mark the high-water mark on their walls and mailboxes today.

The painful lesson is that hurricane preparedness and the ability for first responders to do their jobs depends as much upon where the water will eventually end up as where the winds will hit.

But it’s hard for anyone to really assess those details. Florida’s existing floodplain map is woefully out of date and inaccurate. Most Floridians believe that if things get really bad in a storm, law enforcement and first responders will come to our rescue. But if the data they are relying upon is not accurate, their efforts can be significantly delayed at the very moment when time is of the essence.

The Florida Legislature addressed the problem this year. The House Select Committee on Hurricane Preparedness listed updating the state’s floodplain map as one of its most important recommendations to make the state more resilient against future storms. And the full Legislature responded, including money in this year’s budget to undertake a complete remapping of the state for more detailed floodplain data.

State officials created a map decades ago using a technology called linear light detection and ranging, or LiDAR. That data is still used for everything from zoning and real estate platting to flood zone mapping and civil engineering. But technology has progressed well beyond the standard LiDAR used to create the outdated maps still relied on today.

The difference between the outdated technology and what is available today is like the difference doing your own taxes with pen and paper and an old adding machine versus doing them with a sophisticated computer accounting program.

Since newer technology is available, the state should put it to good use. It’s called Geiger-mode LiDAR and it captures higher-resolution 3-D data from a greater altitude, meaning it is more efficient and can cover large areas of land more quickly. It also penetrates through foliage more effectively and removes shadows and voids. The result?  Much better data gathered faster and at less cost. North Carolina used Geiger-mode LiDAR to provide details for its state flood risk mapping tool, putting officials in a better position to predict, plan for, and deal with natural disasters. And the company that provides it – Harris Corporation – is not only based in Florida, but employs more than 6,000 people in the state and spends more than $200 million with state-based suppliers and vendors.

Having a more accurate map of the state is imperative for local and state officials to make more informed storm preparation and response decisions. It would allow first responders to have a more accurate picture of which streets might be flooded and impassable. Telecommunication companies would be able to identify the best location for radio towers and microwaves to ensure communication devices are effective. Investing in cutting-edge technology would reap great returns for the state.

Florida officials should heed the lessons Irma brought a year ago and create a new floodplain map using the best technology possible. As Floridians learned the hard way, we need to be ready for what nature brings our way.


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