Historical Damaging Events On Watercourse Crossings: An Analysis In Southern Italy

Urbanization of mountainous areas characterized by rough morphology implies the construction of road networks intersecting the drainage streams by means of bridges, culverts, or low water crossings. Historical data on the occurrence of damage caused by floods or sediment-laden flows are a key element for the identification of critical road sections prone to future impacts with geo-hydrological processes. In this contribution, we present a database of historical information on geo-hydrological damaging events affecting road and railway networks in correspondence of watercourse crossings in the Calabria region, southern Italy. This region is characterized by a rugged orography, steep slopes, and few plains, resulting in a large number of small drainage basins, high relief energy, and remarkable river bed load. Here, during extreme weather periods, the road network is the most frequently and intensely damaged element. Direct damage consists in breakage of road sectors and bridges, often affecting people travelling. Indirect damage involves the effects on society, which result in a loss of revenue and tourism, and increased times and costs from longer driving distances due to road blockages. The database has been built using the typical historical data sources as chronicles, diaries, historical books, local and regional agencies, press archives, scientific papers, and documents of Civil Protection offices. It includes spatial and temporal information on more than six hundred events of breakage or damage to watercourse crossings on several types of road and railway, occurred in the region from 1902 to 2016. We analyzed the historical records identifying the affected municipalities and basins, and generating descriptive statistics on data. Furthermore, we analyzed the geomorphometric properties of the basins subtended by the points representing the locations of the damaging events, in order to search for relationships between the basins features and damage, and to characterize all the other basins subtended by each road crossing in the region. Such analysis and related results can be useful for regional infrastructural planning and emergency response, or as a framework of those critical points that either must be monitored during floods or needing reinforcement works.