Coupled Wave Energy and Erosion Dynamics along a Salt Marsh Boundary, Hog Island Bay, Virginia, USA

Abstract

The relationship between lateral erosion of salt marshes and wind waves is studied in Hog Island Bay, Virginia USA, with high-resolution field measurements and aerial photographs. Marsh retreat is compared to wave climate calculated in the bay using the spectral wave-model Simulating Waves Nearshore (SWAN). We confirm the existence of a linear relationship between long-term salt marsh erosion and wave energy, and show that wave power can serve as a good proxy for average salt-marsh erosion rates. At each site, erosion rates are consistent across several temporal scales, ranging from months to decades, and are strongly related to wave power. On the contrary, erosion rates vary in space and weakly depend on the spatial distribution of wave energy. We ascribe this variability to spatial variations in geotechnical, biological, and morphological marsh attributes. Our detailed field measurements indicate that at a small spatial scale (tens of meters), a positive feedback between salt marsh geometry and wave action causes erosion rates to increase with boundary sinuosity. However, at the scale of the entire marsh boundary (hundreds of meters), this relationship is reversed: those sites that are more OPEN ACCESS J. Mar. Sci. Eng. 2015, 3 1042 rapidly eroding have a marsh boundary which is significantly smoother than the marsh boundary of sheltered and slowly eroding marshes.

A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

“…S7), which reads Gðx; a, bÞ = exp −exp − x − b a , −∞ < x < ∞, [4] with a and b being the distribution parameters. If M k H is the maximum value during the k month and GðxÞ is the variable Gumbel distribution function, the N year return period, s N , is…”

“…salt marsh | resilience | hurricanes | wind waves | erosion T he potential of salt marshes to serve as natural buffers against violent storms seems even more important in view of significant threats imposed by climate change, such as increased storminess and higher hurricane activity registered in the past decades (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Recent research results show that salt marshes reduce wave energy during storms and possibly, mitigate storm surges (13)(14)(15).…”

Effects of Marsh Edge Erosion in Coupled Barrier Island‐Marsh Systems and Geometric Constraints on Marsh Evolution

“…In Walters et al (2014), in the long-term this narrow marsh state almost always eventually progrades to fill the basin or drowns. However, Walters et al (2014) did not consider the effects of wave edge erosion, which is a primary cause of marsh loss (e.g., Leonardi & Fagherazzi, 2014;Marani et al, 2011;Priestas et al, 2015). Such model simplification and the intentional omission of the some of the processes and interactions occurring in complex natural morphodynamic systems can facilitate insights about what processes and interactions are most important in those systems (Murray, 2003).…”

Salt marsh erosion rates and boundary features in a shallow Bay

“…As an example, salt marshes in the southeast England have been found to more rapidly accrete right behind the erosional front [e.g., Day et al, 1998]. In spite of accretion rates being spatially variable, numerous studies confirm that feedbacks between sediment deposition, organic matter accretion, and biomass production generally allow salt marshes to be stable on the vertical direction and keep pace with sea level rise [e.g., Cundy and Croudace, 1996;van der Wal and Pye, 2004;Temmerman et al, 2003Temmerman et al, , 2005Temmerman and Kirwan, 2015;Kirwan et al, 2016;Priestas et al, 2015].…”