Build barriers to protect littoral freshwater marshes from rising water levels and severe weather
Overall effectiveness category No evidence found (no assessment)
Number of studies: 0
Background information and definitions
Littoral wetlands (on sea or lake shores) are vulnerable to physical damage from strong waves, and from excessive flooding linked to storm surges and rising water levels. These threats may be reduced by building barriers such as dykes, walls, breakwaters, reefs, groynes, coconut-fibre rolls or even additional marshes or swamps. Barriers can provide some immediate shelter from wave energy. They can also encourage sediment deposition, potentially helping existing marshes or swamps to keep up with sea level rise or building a surface at suitable elevation for emergent vegetation (Wetlands International 2016). Barriers could be installed temporarily to protect colonizing vegetation, or could be used as permanent protection.
Caution: Littoral areas are naturally exposed to wind, waves and flooding. Some disturbance from these elements may be necessary to maintain a diversity of coastal habitats and normal wetland functions. For example, restricting tidal influx to coastal marshes may limit their natural tendency to accumulate sediment and organic matter to keep up with sea level rise (Redfield & Rubin 1962; Nyman et al. 2006). If barriers are left in place for many years, it may not be possible to ever remove them without flooding the marshes or swamps they were intended to protect.
Related actions: Build barriers to protect littoral areas from boat wakes; Divert/replace/block saltwater inputs; Use artificial barriers to block pollution; Use fences or barriers to protect planted areas.
Nyman J.A., Walters R.J., Delaune R.D. & Patrick W.H. Jr. (2006) Marsh vertical accretion via vegetative growth. Estuarine, Coastal and Shelf Science, 69, 370–380.
Redfield A.C. & Rubin M. (1962) The age of salt marsh peat and its relation to recent changes in sea level at Barnstable, Massachusetts. Proceedings of the National Academy of Sciences USA, 48, 1728–1735.
Wetlands International (2016) Mangrove restoration: To Plant or Not To Plant? Available at https://www.wetlands.org/publications/mangrove-restoration-to-plant-or-not-to-plant/. Accessed 1 February 2020.