Hydrodynamic and sediment transport modelling in the canals of Venice (Italy)

A framework of numerical models was applied to the canal network of Venice in order to simulate hydrodynamics and sediment transport. A two-dimensional finite element model (SHYFEM) was applied to the whole surrounding lagoon using water levels as a forcing. The computed levels were extracted along the contour of the city of Venice and then a link-node model was run in the canal network. The simulated variables were calibrated and compared with data from field measurements. Calculated water elevation displays a good agreement with the measured data, and current velocity is well reproduced. Simulations were initially carried out using a constant Manning parameter (MC) and successively a varying coefficient (VMC) was adopted, in order to account for the different depths of the canals. By applying the sediment transport module an evaluation of the sediment accumulation rate in the canal network was obtained, permitting an estimation of the yearly silting up of the canal bed. Different simulations were carried out considering material input from both the city and the lagoon. The model is able to reproduce the overall accretion rate of the canal bottom, and it is a useful tool for planning the dredging activities in the whole canal network.