Flood management measure: Coastal setback

Definition

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.

Co-benefits and impacts

Setbacks provide a highly effective method of minimising property damage due to coastal flooding and erosion, by removing structures from the hazard zone. They provide a low-cost alternative to shoreline erosion or flood protection. Unlike hard structures, setbacks help to maintain the natural appearance of the coastline and preserve natural shoreline dynamics. This allows natural erosion/accretion cycles to occur and helps to maintain the local sediment budget. Enhanced downdrift erosion as observed when using hard defences is also less likely to occur. As such, setbacks can contribute significantly to sustainable management of coastal systems. Setbacks also help to maintain shoreline access by preventing development immediately on the seafront as well as providing open space for the enjoyment of the natural shoreline. Coastal setback zones are commonly promoted as open public recreational space and they can also provide recreational and beach access. Minimum elevation setbacks also provide higher levels of protection when compared to hard defences. For example, if a water level in excess of the design standard occurs, an elevation setback will result in shallower and less extensive flooding of developed areas than would occur if hard defences were employed instead.

Comments

https://www.ctc-n.org/technologies/coastal-setbacks

Approach

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Measure type

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Problem type

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Scale

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Time scale

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Land uses

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Last modified: June 29, 2020, 12:39 p.m.