Architettura deposizionale ed idrodinamica di una barra tidale nella zona settentrionale della Laguna di Venezia

The present work focuses on a tidal bar of the Northern Venice Lagoon, and it is based on investigation of aerial photos, sedimentary facies analyses and 3D modelling. The study of aerial photos highlighted that, since 1968, the bar migrated seaward with a rate of about 20 cm/yr. Moreover the bar migration occurred without any change in sinuosity or bar profile, therefore the bar can be labeled as a translational bar in terms of planform behavior. Bar deposits were studied through 63 sedimentary cores (2-3 m deep). These cores were analyzed on the base of facies analyses principles, which allowed to distinguish between saltmarsh, channel lag, bar and subtidal platform deposits. Spatial correlation (3D modelling) between the main stratal surfaces highlighted that bar accretion was controlled by flood flows, whereas bank retreatment was induced by ebb flows. Finally, it was also noted that bar migration occurred under aggradational conditions, which were linked with vertical growth of the surrounding saltmarshes.