Impact details: inundation

impact chain for tropical coastal areas / sea-level rise (click nodes to view details):
selected case study results:
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Gilman, E. L., Ellison, J., Duke, N. C., & Field, C. (2008). Threats to mangroves from climate change and adaptation options: a review. Aquatic Botany, 89(2), 237-250. Global Sea-level rise is considered to be the biggest threat to mangrove ecosystems when the rate of mangrove sediment accretion and elevation is exceeded by the rate of relative sea-level change. Relative sea-level change is the observed change in water level at a particular point, relative to the level of the nearby land. Sea-level rise induces erosion and weakening of root structures, increased salinity, and too high duration, frequency and depth of mangrove inundation which can go beyond mangrove tolerance levels.
Mangroves in environments characterized by sediment deficits (e.g. in low relief islands with a very limited number of rivers), low ground water tables, and erosion are thought to be the most sensitive to sea-level rise. However, various surface and subsurface processes control the rate of mangrove sediment surface elevation, and thus their ability to accommodate sea-level rise, but these processes are poorly understood.
To enhance resilience to relative sea-level rise, activities within the mangrove catchment can be conducted to minimize long-term reductions in sediment or enhance elevation. These can include, for example, limiting the development of impervious surfaces within the mangrove catchment and managing rates and locations of groundwater extraction. Such activities can reduce alterations to natural groundwater recharge which influences mangrove elevation. Limiting human activities that reduce mangrove soil organic matter accumulation, such as deforestation and pollution inputs, can contribute to maintaining relatively natural controls on trends in sediment elevation. Depending on the tree species and nutrient added, nutrient enrichment can also have a positive effect. Enhancement of mangrove sediment accretion rates, such as through the beneficial use of dredge spoils, could also augment mangrove sediment elevation but excessive or sudden sediment depositions should be avoided.

Krauss, K. W., Cahoon, D. R., Allen, J. A., Ewel, K. C., Lynch, J. C., & Cormier, N. (2010). Surface elevation change and susceptibility of different mangrove zones to sea-level rise on pacific high islands of Micronesia. Ecosystems, 13(1), 129-143. Australia / Oceania High islands are subjected to erosion over time which constitutes an important source of sediments for mangrove forests. These sediments offer mangroves a potentially important means for adjusting surface elevation with rising sea level. Mangrove surface elevation change varies by hydrogeomorphic setting and rivers, suggesting differential susceptibilities among Pacific high island mangroves to sea-level rise. Fringe, riverine, and interior settings registered elevation changes of -1.30, 0.46, and 1.56 mm y-1, respectively, with the greatest elevation deficit (-3.2 mm y(-1)) from a fringe zone on Pohnpei and the highest rate of elevation gain (4.1 mm y(-1)) from an interior zone on Kosrae. Fringe mangrove forests are most susceptible to sea-level rise. Protection of fringe mangroves from anthropogenic disturbances ( for example, harvesting) may slow down mangrove inundation and conversion due to sea-level rise.

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