Experimental observation on bank retreat of salt marshes

Salt marshes are among the richest ecosystems in terms of productivity and species diversity, providing habitat to a diverse fauna population, important resources for fishing and recreation, and a nutrient buffer at the land-sea interface. For these reasons salt marsh erosion represents a heavy loss of soil and this complex phenomenon has enhanced more and more interest, among the scientific community, to understand and quantify physical and biological processes and the related feedbacks to the planimetric evolution of the tidal channels forming the drainage network inside the salt marshes. The present work focuses on the retreat processes of the scarps delimiting the salt marshes due to the impact of wind and tidal waves. To this aim, a physical model reproducing a salt marsh bank was build in a laboratory inside a long wave current flume. The laboratory model (geometry, dimensions, material), the tidal excursion and the wind wave climate were reproduced according the field observations collected in the Venice lagoon. Experimental observations and laboratory measurements allowed revealing the key mechanisms responsible for the bank retreat.