A partition of the Venice Lagoon based on physical properties and analysis of general circulation

A finite element model, previously released and calibrated, is used to partition the lagoon of Venice into a number of physically homogeneous areas, and to investigate propagation of tide waves, water level set-up and internal circulation in the lagoon of Venice. Spatial distribution of passive tracers released at the three inlets led to the identification of the boundaries between the four subbasins in which the lagoon could be subdivided. The analysis of the spatial distribution of salinity, as a result of freshwater discharge from rivers and exchanges with the sea, suggested a further subdivision of each subbasin into three smaller areas: one dominated by river influence; one dominated by sea influence; and one with intermediate characteristics. The final result is a partition of the lagoon into 10 areas, based on physical processes, which can be used to discuss and quantify the general circulation under the influence of different forcing scenarios. Monthly fluxes among different areas are evaluated, thus providing a box model of the lagoon, which could be used by people who do not want to delve into the complexity of a real coupled model, but want to make a first-order assessment of interactions among physical, chemical and biological factors in a spatially non-homogeneous frame.