Hydrodynamic Modelling of the Cabras Lagoon: Water Ciculation and Residence Times

In this work the hydrodynamic circulation and the renewal capacity of the Cabras Lagoon in Sardinia have been investigated with a 2D hydrodynamic model. Using the finite element method, the model solves the circulation pattern of the lagoon induced by different meteomarine forcing such as tide, wind and rivers. The distribution of a conservative dissolved substance subjected to transport and diffusion processes has been simulated in order to compute the water residence time. The simulations have pointed out the action of the wind as the main forcing for the water circulation and mixing of the Cabras Lagoon, while the tide determines the discharges through the inlets between the lagoon and the sea and modulates the circulation pattern set up by the wind. The rivers don't influence significantly the hydrodynamic circulation but have a great influence on the lagoon renewal capacity.