Coastal setbacks are an demarcated area where all or certain types of development are prohibited. Coastal setbacks can be measured either as a minimum distance from the shoreline for new buildings or infrastructure facilities, or may state a minimum elevation above sea level for development. Setbacks determined by distance from the shore are used to combat coastal erosion, while setbacks determined by evaluation are used to control flooding.
Based on kindly provided information by the ClimateTechWiki and the TNA Guidebook on 'Technologies for Climate Change Adaptation' by Matthew M. Linham & Robert J. Nicholls
A set back can be determined at a fixed distance or it can be ‘floating’ and adapt t the dynamic of an area’s topography and shoreline movement. Setbacks can also cover parts of a shoreline or area, or an entire administrative zone. It is important that setbacks are strategically placed in relation to historic erosion or water level rates, rather than by arbitrary placement.
Advantages
Setbacks are considered low cost and less intrusive than solid barriers such as sea walls and dikes. Setbacks maintain natural vegetation and shorelines and allow for the natural dynamics and rhythms of the shoreline to exist and are considered an environmentally sustainable measure for this reason (NOAA 2010). Setbacks can also have spillover benefits by making the shoreline accessible and providing open public recreational space.
Disadvantages of the technology
One of the disadvantages of setbacks is that they are vulnerable to a changing sea line and specifically sea level rise. For this reason, setbacks must be re-evaluated over time to ensure that the buffer zone provides continued protection in light of a changing environment.
Another important point, is that setbacks are not necessarily capable of protecting against strong storm surges and associated flooding and therefore a certain level of risk remains when implementing them as a protection measure.
The nature of setback zones is also subject to controversy because it implies that an area cannot be built on and development of the coast in certain areas cannot take place. This can result in conflicts between users or in the case of a reassessment can even mean that existing structures are newly within the no-build zone. Often structures are allowed to remain, or are compensated for having to move.
Financial requirements and costs
Again, the costs of implementing a coastal setback approach will be variable, depending on local conditions. A number of costs will be incurred when implementing setback in any situation. They are discussed below.
Firstly, a decision must be taken as to how far to set back. Costs involved in taking this decision include the collection and analysis of historic erosion rates or water levels, the cost of modelling likely shoreline evolution, and the associated cost of buying in modelling services and expert consultation. The cost at this stage will vary depending on the method used to determine setback distance. Less technical solutions are likely to be cheaper.
Secondly, the setback policy must be communicated to relevant bodies in order that the policy is taken into account in the planning process. Costs involved at this stage may also involve the additional costs of incorporating coastal setback into local planning policies.
Finally, enforcement is essential. The cost of enforcement may however be low as it is possible to enforce setback via pre-existing local planning bodies.
Additional costs may be incurred if private landowners are required to be compensated for loss of development potential and also when the setback distance undergoes periodic review.
Implementation of a setback policy is likely to have the lowest costs when implemented proactively, before significant, inappropriate development occurs. In this way it should be possible to minimise compensatory payments to private landowners.
Barriers to implementation
One of the challenges associated with implementing setbacks is public opposition. Land ownership and coastal development are often contentious issues, particularly if setbacks require restrictions that affect individual landowners. In such cases, landowners can be compensated for costs of lost development, however, this also increases the costs incurred from implementing a setback.
Many coastal areas also experience pressure to develop the coast for touristic purposes. In many instances, coastal regulation that has been put in place to protect the coastline is overridden in the face of development (Sanò et al., 2010).
Opportunities for implementation
Implementing setbacks is an issue closely related to land use and building regulations and is therefore dealt with by the same policies that regulate building standards. Environmental policy, therefore, has an opportunity to be streamlined into these policy areas.
Setbacks are complimentary measures, meaning that they benefit when implemented in combination with other measures such as sand dune reconstruction or wetland restoration. Implementing a setback in unison with dune reconstruction or wetland restoration helps to ensure that these areas are left alone to properly develop and also improve the capacity to act as a buffer to coastal flooding and erosion.