Salt marsh edge erosion due to wind-waves is one of the chief mechanisms leading to marsh area reduction in various parts of the world. This entails the loss of a large amount of ecosystem services in estuarine and coastal environments. The present research seeks to improve the knowledge on the erosion of the boundaries of the salt marshes, focusing on the spatial scale of the salt marsh bank and the adjacent mudflat. The topic is addressed through three different approaches. The interpretation of laboratory experiments, previously carried out, inspired the development of a mathematical model describing the incipient mass failure of toppling type. The model is able to identify the wave group responsible for the failure of a block of soil identified by the presence of a tension crack and gives information about the combinations of water level and wave height leading to bank instability. A field campaign was carried out on a salt marsh of the lagoon of Venice. Localized and detailed measurements of erosion and wave climate allowed to determine a relationship between wave power and erosion rate at monthly time scale. Field data also demonstrated that in the monitored area the lower part of the bank is more prone to erosion than the top, leading to the formation of cantilever profiles. A simple mathematical model based on field data shows that the different erodibility of the marsh scarp along the vertical profile can lead to a higher cumulative retreat of the marsh edge. The development of a 1-D process-based model allowed to investigate, through numerical experiments, the effect of variations of soil composition on the evolution of the bank profile, with and without vegetation. A muddy bank tends to retreat by maintaining the steep profile of the cliff, whereas decreasing the mud fraction the bank attains a more gentle profile. The effect of vegetation in strengthening the soil matrix against shear erosion is negligible for muddy banks and significant for sandy banks. Independently of soil composition, vegetation makes the bank to retreat maintaining a steep profile. Present research gives several insights into the process of erosion of salt marsh edges due to the effect of wind-induced waves. Obtained results can be employed to evaluate and plan measures aimed at the preservation of salt marsh area and they also lay the base for future researches in the field of the morphodynamic evolution of tidal environments.


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    Title :

    Salt marsh edge erosion due to wind-induced waves


    Additional title:

    Erosion von Salzmarschrändern durch winderzeugte Wellen


    Contributors:

    Publication date :

    2015



    Type of media :

    Miscellaneous


    Type of material :

    Electronic Resource


    Language :

    English


    Classification :

    DDC:    627





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