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New maps update outdated floodplain data in Kent and Sussex

lewes-flooding.jpg
University of Delaware/Delaware Sea Grant
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DNREC has issued new floodplain maps for Kent and Sussex Counties.

 

These preliminary maps address inaccuracies with current maps by updating understudied areas.

 

Places with less residential development tend to show data that are based on watershed studies that date back to the 1970s.  

“That’s been identified as a major issue all over Delaware--that we still have, in all three counties, these areas that really never had a modern floodplain identified," said Michael Powell, who manages DNREC’s Natural Hazards Program.  

He added that the current and previous maps haven’t been useful to more inland, less populated communities.

 

"These folks who live in Bridgeville, Greenville or Harrington, they get new floodplain maps but their floodplains don’t change because [the regulators] didn’t look in that area. They just gave them the new floodplain maps because they [studied] the coastal areas again.”

 
The way scientists measure floodplains over the last forty years has also changed. LIDAR technology, that uses lasers to conduct surveys from planes, has allowed more precise readings, so floodplain maps based on old watershed studies represent rather crude measurements, on top of not reflecting the present reality.

To create the new maps, DNREC and environmental consulting company AECOM worked on presenting more accurate information on land elevation levels. These drafts cover 250 miles of streams and high risk flood zones have been identified for the first time in some areas.

 

 

Officials will be hosting an open house April 20 in Milford to inform residents about these new maps. Proposed changes will go through a 90-day appeal period, which hasn’t started yet.

The new maps, upon FEMA approval, could go into effect by this time next year.

 

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