T103 Coastal Storm Impacts in Times of Changing Climate and Sea Levels: Geological Records, Historic Perspectives, and Forecasting

Monday, 11 October 2021
1:30 PM - 5:30 PM
D138

SAN SALVADOR ISLAND AS A NATURAL LABORATORY TO STUDY IMPACTS OF COASTAL STORMS IN THE BAHAMAS

Paper number: T103-12
Program: Technical Sessions
Time: 4:00 PM – 4:15 PM

Authors

Abstract

San Salvador is the most studied of the Bahamian Islands owing to an operational field station since the 1970s. Originally inhabited by the Lucayan people and known as the landing site of Columbus in 1492, the island is now home to <1000 people in small settlements along a circumnavigating coastal road. The island interior is uninhabited, densely vegetated, and has numerous hypersaline lakes nestled among Pleistocene dune ridges. Its small size (163 km2 or 63 sq mi), low topography and isolated location on the easternmost carbonate bank of the Bahamas Archipelago, make San Salvador prone to the impact of tropical cyclones, as documented by many researchers over the last several decades.

Although travel to the island and rapid assessment in the aftermath of storms can be hindered by infrastructure damage, our observations from Jan. 2000 revealed extensive sand beach erosion, dune scarping, overwash, generation of rock rubble, and damage to vegetation by Cat4 Hurricane Floyd (1999), which passed 20-30 nautical miles N-NE of the island. We documented recovery of beaches (2005-2010) after Sept. 2004 Hurricane Frances, and the impact of Oct. 2015 Hurricane Joaquin, both of which passed directly over the island as Cat3 storms. Along the south coast, Joaquin-generated waves overtopped 5m-high cliffs, causing erosion and inundation of the main road by limestone debris. Boulders up to 3 m in diameter were formed, and 1-3 ton boulders from prior storms moved up to 26 m inland. We conducted additional coastal boulder ridge surveys in Jan. 2012, 2013, and 2017 after Hurricanes Irene (Aug. 2011), Sandy (Oct. 2012), and Matthew (Oct. 2016), which passed W of San Salvador as Cat1-2 storms (Sept. 2019 Cat5 Hurricane Dorian passed too far N to impact the island). Recent (2019-2020) RFID (radio frequency identification) tagging of boulders and cobbles, together with high-resolution drone imaging, allowed us to begin assessing impact of winter storms and to enhance our database for future comparative analyses.

Lack of reliable weather and buoy data, and travel and fieldwork costs continue to represent challenges to ongoing work. We also strive to improve collaborations with the people and government of the Bahamas to minimize future human and infrastructure losses due to increasing frequency and intensity of storms coupled with rising sea levels.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-366146

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