UNEP Risoe Centre

Supported technologies


	Coastal setbacks	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 (Cambers, 1998). 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 description of this technology originates from Linham and Nicholls (2010).
	Managed realignment	Managed realignment is able to reduce both coastal flooding and erosion. It is the deliberate process of altering flood defences to allow flooding of a presently defended area. Managing this process helps to avoid uncertain outcomes and negative impacts. It also helps to maximise the potential benefits (Leggett et al., 2004). A number of terms may be used as an alternative to managed realignment. These include managed retreat, dike realignment, dike (re)opening, de-embankment and de-polderisation. The description of this technology originates from Linha
	Beach nourishment	Beach nourishment is an adaptation technology primarily used in response to shoreline erosion, although flood reduction benefits may also occur. It is a soft engineering approach to coastal protection which involves the artificial addition of sediment of suitable quality to a beach area that has a sediment deficit. Nourishment can also be referred to as beach recharge, beach fill, replenishment, re-nourishment and beach feeding. The description of this technology originates from Linham and Nicholls (2010).
	Artificial Sand Dunes and Dune Rehabilitation	Naturally occurring sand dunes are wind-formed sand deposits representing a store of sediment in the zone just landward of normal high tides (French, 2001). Artificial dunes are engineered structures created to mimic the functioning of natural dunes. Dune rehabilitation refers to the restoration of natural or artificial dunes from a more impaired, to a less impaired or unimpaired state of overall function, in order to gain the greatest coastal protection benefits.
	Seawalls	Seawalls are hard engineered structures with a primary function to prevent further erosion of the shoreline. They are built parallel to the shore and aim to hold or prevent sliding of the soil, while providing protection from wave action (UNFCCC, 1999). Although their primary function is erosion reduction, they have a secondary function as coastal flood defences. The physical form of these structures is highly variable; seawalls can be vertical or sloping and constructed from a wide variety of materials. They may also be referred to as revetments.