Interrelations between urban sprawl and national hydro-geomorphological emergencies in Italy

Climate change and urban expansion are significantly contributing to an increase in catastrophic hydro-geomorphological events, which cause huge damage to society and economy. Since Italy is a relevant hot spot for these huge events, it was taken as a comprehensive case study for this work. The general aim is to analyze the interrelations between the recurrence of disasters at the province and municipality level and urban expansion. All the carried-out analyses are based on a dataset of municipalities and provinces affected by recent hydro-geomorphological disasters for which a national-level state of emergency was declared. The database consists of sets of every municipality and province hit by a critical event and included in the national state of emergency, which suffered damages and obtained subsidies for reconstruction in the last 9 years. For this work, the correlation between the recurrence of disasters on a province and municipality basis and urbanization was tested with a series of state-of-the-art indicators of hydrogeological hazard or risk provided by ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale – higher institute for environmental research and protection). Over 300 variables were considered and over 50 were tested, to find out which ones related better with impacts on territories. Starting from 2013 until now, were calculated soil sealing trends in areas at risk. The increase or decrease for each municipality hit by a critical event was analyzed to better understand local territories’ policies and how they face catastrophes. Firstly, it was discovered that in Italy, during the last ten years, there had been more than one hundred events that have required the intervention of National Civil Protection, with the declaration of a national-level state of emergency and the funding of interventions for first aid and restoration. Secondly, the best correlation between risk-related variables and hit municipalities was found considering cumulative months of emergency and the amount of urbanization in areas at medium hydro-geological risk. Lastly, taking into account this information, the study focused on soil urbanization trends: it was found that in each municipality the trend kept increasing at the same rate despite past damages and economic losses. The last focus of this work was, once the test was completed, evaluating the interplays over time between catastrophic events and policies of urban expansion. This work showed how urban expansion is deeply linked to hydro-geomorphological emergencies, demonstrating that at present the medium-hazard areas are underestimated by policymakers and are the main source of damages. Moreover, the urbanization trends for each municipality highlighted how local administrations, despite damages, don’t change their policies.