Morphological signature of the March 2008 swell event on Caribbean beaches

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Extreme waves often produce the most dramatic impacts on depositional shorelines because they exceed normal sedimentary thresholds, reaching areas that are often above the influence of waves and transporting material that is otherwise stable. Extreme waves occur infrequently but often have the dominant influenec on coastal behaviour over several decades or even centuries. They can be generated by different processes. Waves and surges associated with hurricanes and tsunami are well known for their dramatic impact on coastlines of the Caribbean and Gulf of Mexico. Several hurricanes occur in the region annually and every year some islands are affected. However, their impact at any location depends on their path relative to a particular coast. While they can be devastating, their impacts are often quite localised. Thus on any given island they are a relatively infrequent occurrence. Caribbean tsunami too, have a quite localised influence; they do not have the large scale influence of those in the indian Ocean or Pacific. Large swell waves, in contrast, are generated by distant storms and spread over a large area as they radiate from their point of origin. They are consequently a more frequent occurrence on many Caribbean island shorelines than hurricanes and tsunamis and anecdotal evidence suggests them to have an important influence on beach erosion and accretion. The impact of a large swell event in March 2008 was noted by observers throughout the western Caribbean from Guyana to Puerto Rico. In the British Virgin Islands coral was ripped from reefs and thrown inland or deposited on beaches; on exposed coasts beaches retreated by over 30m while on sheltered coasts the waves appeared to push sand onshore. This research project aims to investigate and record the impacts of this event around the British Virgin Islands and to thereby assess directly, the morphological effect of a swell wave event on Caribbean islands.