definition

Beach nourishment is an adaptation technology primarily used in response to shoreline erosion, although flood reduction benefits may also occur. It is the process by which sediment (usually sand) lost through longshore drift or erosion. Beach nourishment is typically part of a larger coastal defense scheme. 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 is typically a repetitive process, since it does not remove the physical forces that cause erosion, but simply mitigates their effects. (Linham M. and Nicholls R., 2010)

Co-benefits and impacts

If performed well, the benefits of nourishment are many and varied. Most importantly, beach nourishment reduces the detrimental impacts of coastal erosion by providing additional sediment which satisfies erosional forces. Shoreline erosion will continue to occur, but the widened and deepened beach will provide a buffer to protect coastal infrastructure and other assets from the effects of coastal erosion and storm damage. Beach nourishment is a flexible coastal management solution, in that it is reversible. It can complement hard protection measures such as seawalls, which may continue to be used as a last line of defence. A wider beach formed through nourishment can reduce storm damage to coastal structures by dissipating energy across the surf zone, protecting upland structures and infrastructure from storm surges, tsunamis and unusually high tides. It is also possible to provide ecological benefits through beach nourishment. Schemes have been shown to provide enhanced nesting sites for sea turtles when designed with the requirements of these creatures in mind. This in turn, may serve to promote ‘eco-tourism’, with consequent development benefits.
Nourishment is not a permanent solution to shoreline erosion. Periodic re-nourishments, or ‘top-ups’, will be needed to maintain a scheme’s effectiveness. This will require regular re-investment but can be viewed as a maintenance cost, such as those associated with hard engineered structures. Depositing sediments onto beaches can generate a number of negative environmental effects, including direct burial of animals and organisms residing on the beach, lethal or damaging doses of water turbidity – cloudiness caused by agitation of sediments – and altered sediment compositions which may affect the types of animals which inhabit the area. Placement of fill material on the beach can disrupt beach and ocean habitats, such as bird and sea turtle nesting, if schemes are not designed appropriately. This is especially the case if sand grain size/composition does not match the native beach materials.
(Linham M. and Nicholls R., 2010)

conditions

Beach nourishment requires a suitable source of sediment to be identified in close enough proximity to the nourishment site. This ensures that costs are kept at a reasonable level. Sediment availability is highly variable around the globe and suitable sources may not be easily found. The increasing popularity of beach nourishment worldwide may therefore cause sediment availability problems as demand increases. This problem is already being experienced in small island settings where sand is frequently carried large distances for nourishment projects. Beach nourishment requires highly specialised equipment and knowledge including dredgers and pipelines that will need to be hired from a specialised contractor. Hillen et al. (2010) have noted the limited number of large contractors available and also highlighted the associated cost increase due to high demand. Local site characteristics will also influence the type and size of dredger which can be used – this can further limit the availability of dredgers. Public awareness of how beach nourishment schemes work can also present a barrier. This is especially the case when using shoreface nourishment or underwater sediment deposition. Using these techniques, the advantages of nourishment may not be immediately noticeable and unless the public are educated on how the scheme works, they may doubt the benefits of nourishment and oppose such projects. The public should also be made aware that nourishment is not a permanent solution and that re-nourishments will be required. If this is not communicated, the public may again believe the scheme has failed and resent further spending on re-nourishment. This will be especially the case if public funding is used to cover nourishment costs.
(Linham M. and Nicholls R., 2010)

comments

Nourishment can also be referred to as beach recharge, beach fill, replenishment, re-nourishment and beach feeding.

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Last modified: Sept. 19, 2016, 7:50 a.m.