Salt Marsh Accretion and Storm Tide Variation: an Example from a Barrier Island in the North Sea

Abstract

We reconstruct past accretion rates of a salt marsh on the island of Sylt, Germany, using measurements of the radioisotopes 210 Pb and 137 Cs, as well as historical aerial photographs. Results from three cores indicate accretion rates varying between 1 and 16 mm year −1 .Comparisons with tide gauge data show that high accretion rates during the 1980s and 1990s coincide with periods of increased storm activity. We identify a critical inundation height of 18 cm below which the strength of a storm seems to positively influence salt marsh accretion rates and above which the frequency of storms becomes the major factor. In addition to sea level rise, we conclude that in low marsh zones subject to higher inundation levels, mean storm strength is the major factor affecting marsh accretion, whereas in high marsh zones with lower inundation levels, it is storm frequency that impacts marsh accretion.

Contribution of tropical cyclones to the sediment budget for coastal wetlands in Louisiana, USA

“…The Sunderbans is also characterized by a decreasing inland trend of inorganic sediment accretion comparable to the trend we observe for the Louisiana deltaic plain. Similarly, accretion rates in a German salt marsh are driven primarily by periods of high storm activity and storm surge events (Schuerch et al 2012). Consistent sediment input from historic and prehistoric storm events has also been observed in New England (Boldt et al 2010) and mid-Atlantic salt marshes (Stumpf 1983).…”

“…The protection and restoration of coastal areas is projected to cost $50 billion in Louisiana alone, and is largely centered on the delivery of sediment to the coastal landscape (CPRAL 2012). It is widely acknowledged that intense, but infrequent and often destructive storm surge events, such as those resulting from tropical cyclones and tsunamis, can result in the deposition of inorganic sediments which may get incorporated into the soil profile (Stone et al 1997;Turner et al 2006;Nanayama et al 2007;Boldt et al 2010;Tweel and Turner 2012a;Schuerch et al 2012). These sediments can increase wetland elevation, slow wetland subsidence, and affect habitat quality (McKee and Cherry 2009).…”

Improved modelling of the impacts of sea level rise on coastal wetland plant communities

“…Increased storminess has been linked to greater sediment accretion in predominantly depositional wetlands (Allen, 2000;Kolker et al, 2009;Schuerch et al, 2012). Ward et al (2014) have shown that increased sediment accretion occurs during periods of greater storminess at both the Tahu and Matsalu sites.…”

“…Previous studies have shown that in predominantly depositional areas, increased storminess and rising sea levels can facilitate wetland development through sediment deposition (Friedrichs & Perry, 2001;French, 2006;Schuerch et al, 2012;Tsompanglou et al, 2012;Ward et al, 2014). A variety of studies have suggested that sediment deposition alone could, in a wide variety of coastal wetlands, keep pace with SLR, thus preventing any large-scale wetland loss (Friedrichs & Perry, 2001;French, 2006;Kirwan and Temmerman, 2009;Mudd et al, 2009).…”

Tales of island tails: biogeomorphic development and management of barrier islands

“…Frequent storm disturbance is probably one of the mechanisms in which low-lying washover complexes can survive for several centuries and how fresh dune slacks are set back through inundation with seawater. For the salt marsh, storm surges are often a constructive rather than a destructive force, as they deposit fine-grained sediment and are vital to its survival (Schuerch et al 2012).…”