|Environment and development
in coastal regions and in small islands
CSI info 4
Coastal setback provisions ensure that development is prohibited in a protected zone adjacent to the water's edge.
|A coastal development setback may be defined as a prescribed distance to a coastal feature, such as the line of permanent vegetation, within which all or certain types of development are prohibited.|
Coastal development setbacks have several functions :
Most Caribbean Islands use the high water mark as the baseline for measurement. For example, the planning standards developed for the countries belonging to the Organization of Eastern Caribbean States (OECS) (Wason & Nurse, 1994) use it for measurement. However, there are several problems with the use of this criterion. For instance the position of the high tide mark varies from day to day, sometimes its position can change by more than 10 m from one day to the next, particularly if there is a winter swell event. It is also somewhat subjective unless defined by an accurate vertical height, which is not the case in the Caribbean Islands. Thus developers and planners may differ in the interpretation of high tide mark as a baseline.
Actual setback distances vary worldwide from 8 m in Ecuador to 1 - 3 km in Denmark (Clark, 1996). Most Caribbean Islands have one fixed setback for all their beaches, e.g. the setback for new development in Barbados is 30 m (100 feet) from high tide mark, in the British Virgin Islands it is 15 m (50 feet) from high tide mark. These setback distances are rather low, particularly if there is a major event such as a tropical storm or hurricane.
Nevis, on the other hand has developed a setback policy for major tourism beaches whereby a much greater distance is left between new buildings and the high water mark. Here all development is prohibited in the zone extending 37 m (120 feet) from high tide mark, piled structures such as beach bars are allowed in the zone 37 m to 91 m from high tide mark and major hotel structures have to be 91 m (300 feet) from the high tide mark. From a beach dynamics perspective, these setbacks are beneficial, however, from a developer's viewpoint, these setbacks leave a lot of valuable land tied up and unavailable for development, and they have met with considerable resistance in Nevis.
Wason & Nurse (1994) have suggested the following preliminary guide to setbacks from high water for the OECS:
slopes less than 1:20 30 m (100 ft);
slopes 1:4 to 1:20 15 m (50 ft);
coastal cliffs 1:1 or greater 8 m (25 ft).
These guidelines are qualified with the statement that they are subject to studies to determine the highest contour normally reached by high seas.
Some states in the USA utilize variable setbacks which make allowances for natural variations in shoreline trends from one beach to another. For instance in South Carolina, the width of the setback is prescribed as a distance 40 times the annual erosion rate measured from the most seaward dune (National Research Council, 1990).
Since there is a need for further development in the coastal zone in the interests of the islands' economic well-being, setback policies must be designed to ensure that new development is sustainable. The concept of variable setbacks, which make allowances for differences in the behaviour, characteristics, erosional history and use of beaches, can best fulfill this function in the Caribbean Islands.
However, it must be recognized that it is one matter for planners to prescribe setbacks, but in order for them to be successful, groups such as architects, draftsmen, developers and the general public, must be shown the rationale and the need for such planning tools. As with other facets of coastal area management, the need for education, participation and communication is of paramount importance.