Aug 11, 2014

Accelerated flooding along the U.S. East Coast

Tal Ezer and Larry P. Atkinson
Earth's Future AGU Publication
  • States that recent studies identified the U.S. East Coast north of Cape Hatteras as a “hotspot” for accelerated sea-level rise (SLR), and shows that the area is also a “hotspot for accelerated flooding"
  • Finds the duration of minor tidal flooding [defined as 0.3 m above MHHW (mean higher high water)] has accelerated in recent years for most coastal locations from the Gulf of Maine to Florida
  • Finds the average increase in annual minor flooding duration was ∼20 h from the period before 1970 to 1971–1990, and ∼50 h from 1971–1990 to 1991–2013; spatial variations in acceleration of flooding resemble the spatial variations of acceleration in sea level
  • Finds the increase in minor flooding can be predicted from SLR and tidal range, but the frequency of extreme storm surge flooding events (0.9 m above MHHW) is less predictable, and affected by the North Atlantic Oscillations (NAO)
  • Finds the number of extreme storm surge events since 1960 oscillates with a period of ∼15 year and interannual variations in the number of storms are anticorrelated with the NAO index
  • Finds that with higher seas, there are also more flooding events that are unrelated to storm surges
  • Results indicate that previously reported connections between decadal variations in the Gulf Stream (GS) and coastal sea level may also apply to short-term variations, so flood predictions may be improved if the GS influence is considered