Ryan S. Mieras, Christopher S. O’Connor, and Joseph W. Long, 2021. “Rapid-response observations on barrier islands along Cape Fear, North Carolina, during Hurricane Isaias”, Shore & Beach, 89(2), 86-96.
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http://doi.org/10.34237/10089210
Rapid-response observations on barrier islands along Cape Fear, North Carolina, during Hurricane Isaias
Ryan S. Mieras(1), Christopher S. O’Connor(2) and Joseph W. Long(3)
1) Assistant Professor, Physics and Physical Oceanography, University of North Carolina Wilmington, Wilmington, NC, USA
2) Graduate Student in Marine Science, University of North Carolina Wilmington, Wilmington, NC, USA
3) Assistant Professor, Earth and Ocean Sciences, University of North Carolina Wilmington, Wilmington, NC, USA
Corresponding author: Ryan S. Mieras, mierasr@uncw.edu, (910) 962-2475
Hurricane Isaias struck the Cape Fear Region of North Carolina around 23:00 EDT on 3 August 2020, making landfall at Ocean Isle Beach as a Category 1 storm with peak wind speeds of 80 mph. An array of nearshore Sofar Spotter wave buoys captured the wave field at two beaches off the coasts of Bald Head Island (south-facing and east-facing beaches) and Masonboro Island. Local variations in significant wave height and peak wave direction were observed along the Lower Cape Fear Region, due to large shoal features impacting the regional wave climate. A cross-shore transect of five pressure sensors was installed at the north end of Masonboro Island 2.5 days prior to landfall to measure storm surge, wave runup, and variation of gravity/ infragravity wave energy across the barrier island. The three fast-sampling wave gauges along the backshore became buried before Hurricane Isaias peak storm surge, and the two gauges on and behind the dune were never inundated. A low-cost (< $250) Storm Surge Observation Camera (SSOC) prototype captured storm surge and coastal erosion at Kure Beach, in conjunction with pre- and post-storm RTK GPS beach profile surveys. Kure Beach experienced more than 1.0 m of vertical erosion of the berm, while Masonboro Island experienced around 0.1 m of accretion across the backshore, despite nearly identical wave and wind forcing conditions at the two beaches separated by ~20 km. Pre-storm berm height and width (higher and wider at Kure Beach), as well as foreshore slope (steeper, 1:9, at Kure Beach), are likely factors influencing significant erosion at Kure Beach, while slight accretion was observed at Masonboro Island.