Changes in the wind‐wave field and related salt‐marsh lateral erosion: inferences from the evolution of the Venice Lagoon in the last four centuries

Salt marshes are crucially important ecosystems at the boundary between the land and the sea, that are experiencing significant losses worldwide mainly dictated by the erosion of their margins. Improving our understanding of the mechanisms controlling marsh edge erosion is a key step to address conservation issues and salt-marsh response to changes in the environmental forcing. Here we have employed a complete, coupledWind-Wave Tidal Model (WWTM) to analyse the temporal evolution of the wave field, and in particular of the mean wave-power density, in the Venice Lagoon over the past four centuries (from 1611 to 2012). We have then related wave-field changes to the observed erosion patterns determined by comparing recent aerial photographs (1978–2010) and historical bathymetric data. The results of our analyses from the Venice Lagoon show that, while wave-fields did not significantly change from 1611 to 1901, a rapid increase in wave-power densities occurred in the last century. This is suggested to depend on the positive feedback between relevant morphological evolutions and changes in the wave field, both influenced by natural forcing and anthropogenic pressures.We also emphasize the existence of a strong positive linear relationship between the volumetric marsh erosion rate and mean wave-power density. We thus suggest that relating salt-marsh lateral erosion rates to properly computed mean wave-power densities provides a valuable tool to address long-term tidal morphodynamics.