Researchers at Old Dominion University have discovered a trend of sea level rise in their new study of flooding events on the Atlantic coast of the United States over the past four decades.

Tal Ezer and Larry Atkinson, professors in the Department of Ocean, Earth and Atmospheric Sciences and faculty of ODU's Mitigation and Adaptation Research Institute (MARI), found an average increase in annual minor flooding events along the East Coast from Maine to Florida of about 50 hours from the 1971-1990 to 1991-2013.

In some places, such as the city of Norfolk, where ODU is located, the increase in annual flooding during this period was much larger, from about 40 hours in 1971-1990 to almost 130 hours in 1991-2013.

The study also found evidence of an increase in flooding events that are not associated with storm surges. Instead, they are related to changes in the Gulf Stream. During periods when measurements show a weaker than normal Gulf Stream, Norfolk often experience several days of street flooding every high tide, according to the researchers.

The research was accepted for publication July 16 in the journal Earth's Future of the American Geophysical Union (http://onlinelibrary.wiley.com/doi/10.1002/2014EF000252/full).

"We wanted to better understand the relationship between sea level rise and the risk of flood in low lying areas, so that we could improve our ability to be prepared for future flooding," said Ezer, lead author of the study. "We were surprised how well the changes in the Gulf Stream, as observed off the coast of south Florida many miles away, can predict water levels in Norfolk. We are currently working on research to better understand the mechanism in which changes in ocean currents miles away from shore impact coastal sea level."

While recent studies by several research teams have identified a "hotspot "for accelerated sea level rise along the East Coast north of Cape Hatteras, how the increase affects local areas has not been clear.

Ezer and Atkinson said their research confirms minor, nuisance flooding is directly related to the acceleration in sea level rise and that flooding is increasing in many low-lying areas even with small storms or higher than normal tides. Although increased flooding is seen all along the East Coast, the largest acceleration in both sea level and flood duration was observed at Norfolk and Lewes, DE.

"Flooding is only going to get worse in areas such as Norfolk, " said Atkinson, who was founding director of ODU's Climate Change and Sea Level Rise Initiative (CCSLRI). "Places that only flooded a couple of days a year in the past need to be prepared for more flood days in the future."

CCSLRI, as well ODU's Center for Coastal Physical Oceanography (CCPO), provided partial support for this study.