Coastal Setbacks Technology
The Climate Technology Centre provides a description of coastal setbacks, including advantages, disadvantages, financial requirements and costs, organizational requirements, barriers to and opportunities for implementation.
Coastal setbacks are ‘a prescribed distance to a coastal feature such as the line of permanent vegetation, within which all or certain types of development are prohibited. A setback may dictate a minimum distance from the shoreline for new buildings or infrastructure facilities, or may state a minimum elevation above sea level for development. Elevation setbacks are used to adapt to coastal flooding, while lateral setbacks deal with coastal erosion.
The ‘setback’ area provides a buffer between a hazard area and coastal development. The idea is to allow room for the average high water mark to naturally move inland by SLR throughout the economic lifetime of the property. Setbacks provide protection to properties against coastal flooding and erosion by ensuring that buildings are not located in an area susceptible to these hazards. Two types of setback can be distinguished; elevation setbacks to deal with flooding and lateral setbacks to deal with erosion.
The approach allows erosion to continue along strategic sections of coast while further development is restricted. This allows eroded sediment to be transported to areas alongshore, thus enhancing the level of protection afforded by helping to maintain wide, natural beaches. By managing the coast in this natural state, adjustments by the coastline to changing conditions such as SLR can be made without property loss. Setback distances are determined either as:
- A fixed setback which prohibits development for a fixed distance landward of a reference feature
- A floating setback which uses dynamic, natural phenomenon to determine setback lines and can change according to an area’s topography or measurements of shoreline movement.
Control of development is achieved either by defining a linear exclusion zone along the whole of an administrative unit, or by specifying distinct coastal exclusion zones. Ideally, setbacks should be established based on historic erosion rates or extreme water levels rather than adopting arbitrary distances which do not truly represent the threat from erosion or coastal flooding.
Setback policies are widely used across the world; schemes have been implemented in many countries including Canada, Barbados, Aruba, Antigua, Sri Lanka, USA, Australia, Denmark, Germany, Norway, Finland, Poland, Spain, Sweden and Turkey.