Tidal Prism Variation in Venice Lagoon and Inlet Response over the Last 70 Years

The Venice lagoon inlets have undergone extensive modification during the past, responding in their evolution to the changing physical forcings and human intervention. In order to quantify the adaptation to these forcings the northernmost inlet (Lido) has been studied in detail through numerical modeling and high-resolution bathymetry data collected during three consecutive years. Eleven sections have been chosen in these channels where the cross-sectional area has been determined. The discharges and with it the tidal prism through these sections have been computed through numerical simulations of an existing, calibrated hydrodynamic model (Shyfem). The obtained results have been compared to empirical relationships between the tidal prism and the cross-sectional area of tidal channels (O'Brien relation and Jarrett formula). The computations have been repeated with available data from bathymetry charts for the years 1990, 1970 and 1930 to detect any temporal variation of the cross-sectional areas of the channels and their tidal prism and to evaluate the stability of the Lido inlet. Results from all inlets indicate a relative stability of the tidal prism entering Venice Lagoon, though some changes were detected for the year 1970.