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High-tide flooding could be more frequent in Delaware

Flooding_manhole_cover_7th_St.JPG
Sophia Schmidt, Delaware Public Media
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Water pools on a road on Wilmington's 7th Street Peninsula on a sunny day this spring

The U.S. tied its 2015 record for the median number of days of high-tide flooding in coastal communities last year, according to a report released by the National Oceanic and Atmospheric Administration Wednesday.

Areas of Delaware saw several days of high-tide flooding, also known as “nuisance” or “sunny-day” flooding.

 
 

Coastal flooding now occurs in many locations not just during storms, but during high tides on sunny days as well. NOAA attributes this to land subsidence, loss of natural barriers and climate-related sea level rise. 

 

The new report shows high-tide flooding was most prevalent last year in the Northeast Atlantic region, with records set in the Chesapeake Bay. 

Lead author on the report and NOAA oceanographer William Sweet ties the flooding to one of the effects of climate change. 

“Relative sea levels continue to rise,” he said. “The ocean is now at the brim clogging stormwater systems and routinely flooding U.S. coastal communities with saltwater, often with no storm in sight. This is high-tide flooding. This is sea level rise.”

According to NOAA, Lewes, Delaware saw eight high-tide flood days between May 2018 and April 2019 — and is expected to see up to 12 this year. 

A monitoring station at Reedy Point, Delaware, where the C&D Canal meets the Delaware River, saw four high-tide flood days last year and is predicted to experience up to four again this year. 

The northeast Atlantic region overall is expected to experience a median of 8 days of flooding this year — an increase of 140 percent since 2000, according to the report. 

The report also verified news reports of farmland salting in coastal Maryland and Delaware as a result of high-tide flooding. Sweet says this is likely to continue. 

“Sea level rise is not going down,” he said. “High tide flooding, water over land that’s starting to either directly salt or force subsurface effects are going to continue and they’re going to become more severe in time.”

NOAA predicts Lewes could see up to 30 high-tide flooding days in the year 2030, and as many as 135 such days in 2050.

The predictions for Reedy Point are lower, with up to 15 days of high-tide flooding expected there in 2030 and up to 100 in 2050. 

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