Environment and development in coastal regions and in small islands

Hurricane impact on beaches in the eastern Caribbean Islands 1989 - 1995

9.  SUMMARY

1. Hurricane Hugo in 1989 and the 1995 hurricanes caused severe beach erosion in the eastern Caribbean Islands :  British Virgin Islands, Anguilla, St. Kitts Nevis, Antigua Barbuda, Montserrat and Dominica.  Beaches in other islands, such as St. Thomas and St. Maarten, were also impacted, but no data on beach changes exists for these countries.

2. The variation in beach changes was enormous, some beaches were completely stripped of sand leaving only a bare rock platform, other beaches actually accreted.  Nevertheless when the data were averaged, each island showed severe erosion.  Beach volumes decreased on average by 28% after the 1995 storms.

3. The hurricanes also caused retreat of the land edge or sand dune behind the beach.  This coastline retreat is viewed as a “permanent” change.  There was an inverse relationship between the amount of coastline retreat and the distance from the storm centre.  Within 0 and 40 km of the centre of a category 4 hurricane, the average coastline retreat was between 18 and 5 m.  Within 40 and 180 km of the hurricane centre the average coastline retreat was between 5 and 2 m.  These average figures mask considerable ranges.  The highest coastline retreat recorded was at Meads Bay, Anguilla where the dune edge retreated 30 m inland.

4. Other factors besides the proximity to the hurricane centre, affect the amount of coastal erosion.  These factors include the characteristics of a particular hurricane particularly the position of the strongest sector relative to the island, coastline shape, width of the offshore shelf and local features such as coral reefs.

5. In two islands affected by category 4 hurricanes in 1989 and 1995 for which data exist, the magnitude of the beach erosion was similar during each event.  In addition the geographical variation in the beach erosion in each island was the same in 1989 as in 1995.

6. Major beach recovery takes place in the months immediately after the hurricane.  Data from four islands showed that within eight months of the hurricane, the beaches had recovered to 90% of their pre-hurricane levels.

7. Although major beach recovery takes place immediately after the hurricane, analysis of longer term trends from islands affected by Hurricane Hugo in 1989 showed that the beaches did not fully recover to their pre-hurricane levels.

8. At some isolated sites, particularly in St. Kitts and Antigua, exposure of new beachrock ledges during the hurricane appeared to be impeding beach recovery.

10.  RECOMMENDATIONS 

Conservation of beaches in the eastern Caribbean Islands is fundamental to the region’s economic and social well being.  These small islands should be encouraged and assisted to develop and implement beach management strategies within the overall framework of integrated coastal management (ICM) such that the present crisis management approach to beach conservation is avoided.  In the context of this report which deals specifically with beach erosion, it is necessary to consider management options for certain coastal stretches.  For instance certain coastal stretches with a high level of beachfront infrastructure, e.g. Dickenson Bay in Antigua, may need some form of coastal protection (hard or soft engineering solutions) in the future, while other stretches, e.g. Palm Bay in Barbuda, where there is very little beachfront development, may be left to erode. Such decisions can only be effective within a framework of ICM.

Against this background, recommendations are developed to address the following:

1. research needs,

2. institutional strengthening,

3. education and awareness.

a.  Research Needs  

1. Against the background of information presented in this report, review existing coastal development setbacks for the small islands of the eastern Caribbean.  If necessary, design and implement new setback guidelines for each country based on the concept of variable concepts for individual beaches.    Recently designed setback guidelines for Anguilla which incorporate several factors, including hurricane impact, into the setback computation may serve as a framework (Cambers, 1996b).  This recommendation is in keeping with that proposed by the workshop on “Integrated framework for the management of beach resources within the smaller Caribbean Islands” (UNESCO, 1997). 

2. Develop case studies relating to post-hurricane beach recovery where engineering solutions have been implemented. 

b.  Institutional Strengthening 

1. Maintain the existing beach monitoring programmes and strengthen the beach change databases in each island.  This will involve capacity building and the involvement of several different agencies e.g. environment, planning and public works.  Again this recommendation is in keeping with that proposed by the workshop on “Integrated framework for the management of beach resources within the smaller Caribbean Islands” (UNESCO, 1997).

2. Expand the programme to other small Caribbean islands not presently included.

c.  Education and Awareness

1. Ensure that the information on hurricane impacts on coastal and beach resources is available to every citizen in the islands.  In particular target special interest groups, such as coastal land owners, hotel owners, tourism associations, fishing communities, with information on the impacts of hurricanes on their coastal and beach resources.

2. Provide information and training relating to coastal defence options, to include hard and soft engineering solutions, to planning and other government agencies, as well as the special interest groups outlined in c) (i) above.

11. CONCLUSION 

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