The Global Hydrogeological Risk in Italy, a Threat that is too often Underestimated
Italy is a country that has always been "battered" by hydrogeological breakdowns, landslides, floods; the highly critical areas represent 9.8% of the national surface and cover 89% of the municipalities, on which there are 6,250 schools and 550 hospitals, as documented by an interesting article on "Data Journalism" published by La Stampa's medialab (Italian newspaper). About 6 million people in Italy are threatened by landslides and floods. The following work is intended to be a contribution to the dissemination and circulation of a correct geological culture, in a country where there is no adequate training in Geological Sciences in schools. Although there is a very efficient public civil protection service prepared to deal with emergencies following disasters, it is still too little, what governments and institutions spend on disaster prevention that must necessarily pass for proper training and information of citizens. The present work also wants to propose a concrete solution to the problem, with the presentation of a simple but innovative system to mitigate the negative effects of the large waterproof surfaces present in our cities. The HCS Hydro Control System provides for the creation of "domestic" microbacines, for the storage and reuse of rainwater coming from waterproofed surfaces. It would be very interesting to put the HSC method into practice just as an experiment. Given the vastness and complexity of the survey, mainly cartographic tools such as, thematic maps (Geological map of Italy, maps of natural hazards, historical meteorological bulletins and data published in journalistic articles, ISPRA monitoring data) were used. The excessive vulnerability of the Italian territory must be sought in a series of concomitant factors, starting from the particular geological structure. The relatively recent formation, from the geological point of view of Italy and the islands except Sardinia, dates back to the Middle-upper Miocene (about 8 million years ago), a very short geological period, unlike the rest of the European continent. We must also consider human activities that can only increase the vulnerability of the territory: rapidly urbanized areas in risk areas, increase of impermeable surfaces, and reduction of water runoff lines. There are also some examples of disasters, related to hydrogeological instability, which hit Italy: the Vajont landslide in 1963 and the spread of beta-hexachloro-cyclohexane pollution in the lands of the Sacco river valley in southern Lazio. The analysis of the hydrogeological risk in Genoa, which has always been affected by alluvial events, often destructive, linked to the particular geomorphological conformation of the territory, is an excellent starting point to verify the effectiveness of an important hydraulic work, the drain of the Fereggiano torrent in Genoa, for the derivation, in the case of full of well110 m3/s of water.