The Impact of Shoreline Stabilization on Sediment Supply and Ecogeomorphology: Assessing Marsh Response to Altered Wave Energies, Lake Borgne, Louisiana

Shoreline protection structures are a common response to lateral erosion in marshes, but limited studies exist on how they influence sediment supply and the resulting ecogeomorphology. This study investigates the impacts of marine mattresses, geotextile cages filled with riprap, in Lake Borgne, LA. A field study was conducted during cold front passages at a site with marine mattresses and a proximal control site without, collecting measurements of water depth, wave energy, lateral erosion, sediment accumulation, vegetation, and sediment characteristics. Wetlands with marine mattresses attenuated waves more than their natural marsh edge counterparts, which have limited conditions favorable for sedimentation. However, the lateral position of the marsh was maintained, while the control site eroded at an average rate of 1.7 meters per year. Water content, organic matter, bulk density, salinity, and pH were similar between the sites, but the marine mattress site was lower in elevation and contained finer sediments