Paper No. 46
Presentation Time: 9:00 AM-6:00 PM


PERISON-PARRISH, Elizabeth M.1, RUNYAN, Ryann M.1, SIEMER, Kyle W.2, JACKSON Jr., Chester W.3, BUSH, David M.1, LLERANDI-ROMÁN, Pablo A.4 and NEAL, William J.4, (1)Department of Geosciences, University of West Georgia, Carrollton, GA 30118, (2)Environmental sciences, University of Toledo, 2801 Bancroft Ave, Toledo, OH 49606, (3)Department of Geology and Geography, Georgia Southern University, Statesboro, GA 30460, (4)Department of Geology, Grand Valley State University, Allendale, MI 49401,

The Coastal Vulnerability Index (CVI) is a formula that incorporates key physical and geomorphic parameters that shape the coast to determine potential response to projected sea-level rise (SLR). CVI studies have traditionally been focused on long coastlines. This study develops applies a CVI for small islands associated with Puerto Rico and the U. S. Virgin Islands. Islands with significant ecologic, cultural, historic, recreational, or natural resource value were chosen. A USGS CVI analysis of the U. S. Virgin Islands National Park provided a template for this study.

Coastal dynamics of small islands differ from that of mainland shores, and therefore a classic CVI analysis was deemed inappropriate. The six variables utilized by the USGS are geomorphology, shoreline erosion and accretion rates (m/yr), coastal slope (percent), rate of relative sea-level rise (mm/yr), mean tidal range (m), and mean wave height (m). Those variables do not comprehensively reflect the features and processes at work on small islands in the region. For example, mean tidal range and mean wave height do not vary significantly over the scale of a small island, and so it was removed from our formula. We utilized parameters of vegetation, storm frequency, beach/bedrock composition, and rates of tectonic subsidence/uplift in addition to geomorphology, shoreline erosion and accretion rates (m/yr), coastal slope (percent), rate of relative sea-level rise (mm/yr), and significant wave height. CVI values were computed twice: once in the original USGS format, and again in the newly modified format.

Small islands require much more detailed investigations due to heterogeneity across small distances. In addition, other hindrances in a vulnerability assessment of this nature include data gaps, methodological difficulties, and island accessibility. To address these issues, detailed field mapping was completed for two islands: Cayo Ratoñes and Isla de Cardona. This has resulted in a very general and preliminary vulnerability assessment for the small islands of Puerto Rico. However, once finalized, similar methods may be applied and refined for the mainland coast Puerto Rico and the Caribbean region.