Sediment Accretion Dynamics and Environmental Drivers in CoastalWetlands: Insights from the Wax Lake Delta

This study analyses sediment accretion, river discharge, and wind dynamics in coastal wetlands combining data from the Delta-X project, the United States Geological Survey (USGS), and the National Oceanic and Atmospheric Administration (NOAA). Data covers the period from 2020 to 2023. Sediment accretion data from feldspar marker horizons in the Wax Lake Delta were processed to evaluate organic carbon content and bulk density variations across different hydrogeomorphic zones. Discharge measurements were obtained from USGS monitoring sites, while wind speed data came from NOAA stations. Wind data were filtered using speed and direction thresholds to isolate storm conditions significantly affecting sediment transport processes. All data were processed with MATLAB, aligning all datasets for time-series analysis and exploring interactions between hydrodynamic and atmospheric factors. Statistical and computational analyses explored seasonal sedimentation patterns and the effects of storm events. The results show significant spatial variability, with sediment accretion rates ranging from approximately 17 to 115 mm/year. Storm events with wind speeds exceeding 10 m/s blowing from the sea with prevailing directions between 90° and 270° strongly influence sediment deposition, driven by wind-induced water level changes. Intertidal zones, where accretion is vital for wetland resilience, exhibited elevated sensitivity to discharge peaks and wind-driven dynamics. Sedimentation patterns reveal that seasonal high-flow events are key to sediment supply, particularly during spring and fall. These findings advance our understanding of sediment transport mechanisms in dynamic wetland systems and could suggest strategies for sustainable sediment management. Insights are particularly relevant also for flood-regulated systems, such as the Venice Lagoon (Italy), where altered sediment transport dynamics are challenging for wetland survival and critical ecosystem service maintenance.