Environmental Impacts of Hurricane Irma on the British Virgin Islands

University Of Southern Mississippi, Hattiesburg MS

Investigators

Abstract

With four intense storms making landfall on American and Caribbean coastlines this year, the 2017 hurricane season highlights the need to better understand the geographic and temporal controls on hurricanes in the Atlantic region. This RAPID project represents a unique opportunity to understand the impact of a Category 5 hurricane on the existing paleo-overwash record at previously-studied field sites on Anegada, British Virgin Islands (BVI), one of the islands that sustained the greatest impact from Hurricane Irma. The research team will make careful comparisons between pre- and post-Irma coastal deposits resulting from extreme wave inundation as an important step towards improving the assessment of hazard risk for coastlines that are vulnerable to both hurricane and tsunami inundation. This work will provide important new information regarding hurricane and tsunami hazards, not only for the British Virgin Islands, but for other Caribbean islands including those of the U.S. Virgin Islands and Puerto Rico. By assessing the sediments deposited by Hurricane Irma, the team will develop an important modern analog of a Category 5 storm that will help interpret long-term geologic records of overwash (and episodic tsunami) deposits for the Caribbean region, which will enable Caribbean countries to better prepare for, respond to, recover from, and mitigate future hurricane impacts. The distribution of overwash sediments and boulders at Anegada, BVI captures important information regarding Hurricane Irma's storm surge (flow depths, inundation distances). Through detailed multidisciplinary field and laboratory analyses the team intends to investigate the environmental impacts and overwash deposits associated with Hurricane Irma's landfall on Anegada to: (1) document the storm surge characteristics and associated sedimentary deposit of a known Category 5 hurricane; (2) assess the depth of scour and distance of sediment and boulder transport by storm surge; and (3) use the Hurricane Irma deposit as a basis of comparison with older overwash records, including a series of inferred tsunami deposits within coastal ponds at Anegada. These data will be used to reassess previously documented overwash records that span the last several thousand years and will identify similarities and differences between the sedimentary deposits emplaced by past major storms (e.g., hurricanes in 2010 and 2017) and tsunamis (1755 Lisbon earthquake) at this location. This reassessment of the overwash record at Anegada, based on lessons learned from Hurricane Irma, can be used to reconstruct millennial scale patterns of frequency, intensity, and physical impacts associated with both storms and tsunamis. This refined understanding of extreme wave events will improve hazard prediction, preparedness, and assessment for coastlines impacted by both forms of marine inundation.