Effect of local variability in erosional resistance on large‐scale morphodynamic response of salt marshes to wind waves and extreme events

Printer-friendly version

The presence of natural heterogeneities is an integral characteristic of salt marshes and needs to be account for, as local feedbacks could influence the large scale morphodynamic evolution of these wetlands. Herein, we use field data and a cellular automata model to investigate salt marsh response to wave action under different wave energy conditions and frequency of extreme events.

Our results suggest that salt marsh response to wind waves is tied to their local properties. In case of low wave-energy conditions, a local variability in marsh resistance might lead to the unpredictable failure of large marsh portions with respect to average erosion rates. High wave-energy conditions, while overall lead to faster marsh deterioration, produce constant and predictable erosion rates.

A high occurrence of extreme events causes salt marshes to reach the highest likelihood of large failures for a lower wave exposure, while also leading to smoother, and more uniformly deteriorating marsh boundary profiles. Salt marshes subject to weak wave energy conditions are the most susceptible to variations in the frequency of extreme events. On the contrary, salt marshes exposed to energetic waves remain relatively unchanged in front of such frequency variations. This suggests that variations in time in the morphology of salt marsh boundaries could be used to infer changes in frequency and magnitude of external agents.

Leonardi N, Fagherazzi S (2015) Effect of local variability in erosional resistance on large-scale morphodynamic response of salt marshes to wind waves and extreme events. Geophysical Research Letters 42(14):5872–5879.

Leonardi N, Fagherazzi S (2014) How waves shape salt marshes. Geology . doi:10.1130/G35751.1.