The role of the lagoon in an emergy territorial evaluation for Venice

Human artificial systems always interact with ecosystems which provide a lot of fundamental resources and services. An accounting system, which is able to take into consideration both the economic and natural support to a given territorial system, is necessary for a good and sustainable management of resources. During the '80s, H. Odum developed an environmental assessment of the use of resources by a thermodynamic based methodology: emergy evaluation. The paper presents the case of the Province of Venice, which is very complex due, on the one hand, to the heavy and consolidated presence of industrial activity since the beginning of the 20th century and, on the other hand, to the necessity to preserve the principal natural ecosystem which characterizes Venice: its lagoon, the greater wet zone in the Mediterranean Sea with its 550 km(2). The results of the analysis indicate some critical points and then different paths of a feasible future development under a sustainable perspective. In particular, the relation between human behaviours and the role of lagoon as a provider of natural resources and services is emphasized by presenting some indicators such as the Environmental Loading Ratio (ELR), the Emergy Density (ED), the Emergy per Person (EpP) and the Emergy Investment Ratio (EIR), and putting on evidence the role of lagoon from an analytical point of view.