Abstract:
Monitoring of beach profiles has been conducted by the Department of Fisheries and Marine Resources since 1992 and expanded over the years to now include sixty two study sites spread across nineteen beaches, fifteen on mainland Anguilla and four on its offshore cays. This report details the results from sixteen of these beaches that were studied prior to 2012, before the number of monitoring sites was expanded to its present compliment. Across these beaches, between 1992 and 2014, a total cumulative loss of 332 m in overall beach width has been documented which, when taking into account the number of profile sites per beach, in any given location there has been a mean width loss of 7.1 m. When adjusting based on the number of years each location has been reliably monitored, this in turn equates to a mean beach width loss of 0.7 m/yr-1 . Of the mainland beaches studied, Sile Bay suffered the greatest overall loss per monitoring location with a mean decrease of 20.9 m (1.9 m/yr-1 ), followed by Meads Bay with 16.6 m (0.9 m/yr-1 ), Shoal Bay East with 12.4 m (0.8 m/yr-1 ), and Shoal Bay West with 12.3 m (0.7 m/yr-1 ). Of the offshore cays Sandy Island had the greatest loss in beach width per monitoring location with a mean decrease of 12.6 m (0.8 m/yr-1 ). In total 81% of the beaches suffered from erosional losses, or 79% of all monitoring locations. Reasons behind these losses appear varied and complex, and often due to a lack of recovery following hurricane events or strong ground swell seasons. For the most part this lack of recovery seems to occur where either sand mining for aggregate has removed dune systems or coastal developments (and probable dune removal to facilitate the development) have taken place essentially directly on the beach. Erosion at some sites took place without these influences however (for example Shoal Bay East), with the cause thought to be due to a degrading reef system. Some sites displaying erosion may in part be due shifting sands rather that solely sand loss (for example Sandy Island, Prickly Pear East). Of the two accreting mainland beaches Sandy Hill Bay was highest with a mean overall change per profile location of 1.5 m, followed by Maundays Bay with 1.3 m over the study period. The increases at Maundays Bay are due to a number of beach nourishment programs carried out there following major hurricane events. This study highlights the need for responsible coastal development and implementation of mandatory setbacks, tight regulations relating to coastal sand mining, and the increased protection of important defensive coral reef areas. The study also points to the need for detailed investigations prior to coastal engineering interventions, for while the beach nourishment at Maundays Bay has been successful to date, other interventions at the east end of Barnes Bay have not yet shown any positive impacts. If Anguilla is to preserve its beaches that are a crucial driving force behind its tourist dependent economy then the importance of this cannot be understated.
