Evaluation of Flood and Landslide Risk to the Population of Italy

Abstract

We have compiled a database of floods and landslides that occurred in Italy between AD 1279 and 2002 and caused deaths, missing persons, injuries, and homelessness. Analysis of the database indicates that more than 50,593 people died, went missing, or were injured in 2580 flood and landslide events. Harmful events were inventoried in 26.3% of the 8103 Italian municipalities. Fatal events were most frequent in the Alpine regions of northern Italy and were caused by both floods and landslides. In southern Italy, landslides were the principal agents of fatalities and were most numerous in the Campania region. Casualties were most frequent in the autumn. Fast-moving landslides, including rock falls, rockslides, rock avalanches, and debris flows, caused the largest number of deaths. In order to assess the overall risk posed by these processes, we merged the historical catalogs and identified 2682 "hydrogeomorphological" events that triggered single or multiple landslides and floods. We estimated individual risk through the calculation of mortality rates for both floods and landslides and compared these rates to the death rates for other natural, medical, and human-induced hazards in Italy. We used the frequency distribution of events with fatalities to ascertain the magnitude and frequency of the societal risks posed by floods and landslides. We quantified these risks in a Bayesian model that describes the probabilities of fatal flood and landslide events in Italy.

Flood risk assessment and mapping in peri-urban Mediterranean environments using hydrogeomorphology. Application to ephemeral streams in the Valencia region (eastern Spain)

“…The hydrogeomorphological method has proved to be extremely efficient in interpreting flood processes in this type of intermittentflowing, highly torrential basin in which standard hydrolological and hydraulic models prove inadequate (Ballais et al, 2005;Diakakis, 2011;Díez-Herrero et al, 2008;Guzzetti et al, 2005;Lastra et al, 2008;Ortega & Garzón, 2009 ). This method enables analysis with scarce hydrological data and is highly flexible as any change in the floodable area's morphology (whether natural or human-induced) can be included in a hydrogeomorphological map and be easily assessed in hazard terms.…”

“…Although it is not a quantitative approach, it provides a reliable representation of the processes, it is economical, and in 80% of the cases enables decision-making (Marco, 2006). Applications in Mediterranean areas in the south of France (Ballais et al, 2005;Chave, 2002), Italy (Guzzetti & Tonelli, 2004;Guzzetti, Stark, & Salvati, 2005), and northwestern Spain (Lastra et al, 2008) have shown the effectiveness of the method in torrential basins with changing morphology and large-scale erosion potential in which hydrological information is scarce or non-existent. In this paper, hazard mapping is based on the interpretation and analysis of the floodplain's geomorphology, in terms of hazards.…”

Assessment of data availability for the development of landslide fatality curves

“…A national Italian investigation on landslide risk in the twentieth century revealed that at least 7799 casualties were reported, 5831 lives were lost, 108 missing, and 1860 injured (Guzzetti et al 2003). Extending the time period to the years 1279-2002 and including landslides causing death, missing people, injuries, and homelessness, landslides caused a total of 10,111 fatalities yielding and average fatality rate of 10.1 (Guzzetti et al 2005b). This data set includes the disastrous landslide at the Vajont dam in 1963 that generated an enormous wave, killing almost 2000 people.…”

“…Previous scientifically published quantification on fatalities are, as far as we know, calculated frequency rates for average number of fatalities per event, year, month, day, intensity, area of occurrence or expressed as the number of deaths per 100,000 inhabitants for a given population over a predefined time period (Cascini et al 2008;Giannecchini and D'Amato Avanzi 2012;Guzzetti et al 2005b;Hilker et al 2009;Pereira et al 2014;Salvati et al 2010). Methodologically, the studies differ concerning which observation inclusion criteria that are used when deriving a fatality (or mortality) rate.…”

Rockfall hazard assessment along a road on the Peloritani Mountains (northeastern Sicily, Italy)

“…Therefore, rockfall has been a serious threat in many mountainous areas in the world (Chau et al, 2003;Dorren and Seijmonsbergen, 2003). In Italy, rockfalls represent a primary cause of landslide fatalities (Guzzetti et al, 2005;Palma et al, 2012).…”