La valutazione economica del danno ambientale nelle aree alluvionate del messinese

Natural calamities are damaging events posing serious economic-valuation problems due to their complexity, originated by the not always linear combination of emotional-affective aspects and responsibilities at all levels. They are quite often caused by an insufficient management of the territory, an over-exploitation of the hydro-geologic support, and the symmetrical underrating of the possible consequences of the cumulating tampering of the delicate balance between bearing capability of the natural systems, probability of exceptional events, urbanizations. The social state has guaranteed so far and no longer, even if with different efficiency/effectiveness on the part of the delegated local organizations, emergency, support to the evacuees, the restoration of the damaged private and public heritage, and the securing the involved territories. In the feedback of the flood event in the territory of the hill and coastal areas urban centres located alongside the torrents of the Ionic sea side of the Province of Messina, the essay proposes a patrimonial type valuation approach trying to integrate the territorial aspects, and in particular the characteristics of dangerousness, risk and vulnerability specified by the Sicilian Region’s P.A.I. after the calamity event, in a valuation of damage model inspired by the method of the “ascribed preferences”. The study integrates an analysis and a reflection on the social discount rate, central issue of a vision of territorial capital variously inflected referring to the several hints of the concept of sustainability, represented by the dimension, the articulation and the temporal variation of the essay. In particular, the study indicates, on the grounds of the extensive literature on this subject, the aspects that mainly encourage the choices of territorial policy meant as prevention, due to the difficulty the “ex ante” valuations encounter in the perception of all terms of value destroyed by natural calamities. The proposed model is based on the analysis of the public expense flow in a defined span, and applies an ascribing model of this expense to the studied context in order to perceive the gap between the commitments of the competent authorities for the safeguarding of the territory and the actual restoration costs. The difference between these two amounts can constitute one of the elements of the dimension of the temporal preference rate, and therefore of the perception of the risk of these events.