Extreme precipitations in Italy – November 2022

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Fig.1 | Spatial distribution of extreme precipitations as returned by E3CI indicator, November 2022: Italy (left), Campania region (centre) and Emilia-Romagna region (right)

About the precipitation events over Europe: focus on Italy

As mentioned in the newsletter concerning the month of November, in the C3S Climate Bulletins on precipitation, relative humidity, and soil moisture, wetter-than-average conditions were reported for the coastal regions of the Atlantic, in northern Scandinavia, from central Portugal to southern Norway, and from Italy towards the north-eastern regions (in the regions of Poland and the Baltic States and from the Balkans to Russia) as well as in inland Turkey and north of the Caspian Sea. However, considering the E3CI index, extreme precipitation values larger than 1 have been observed specifically over Italy, Great Britain, and Eastern Europe. By following the E3CI index results, the most affected areas in Italy corresponded to the Emilia-Romagna and the Campania region, with values exceeding 3 (see Fig.1 for more details). More specifically, for what it concerns the latter, the Ischia Island is the place where heavy rainfall events have led to major impacts.

E3CI index on EXTREME PRECIPITATION

One among the indicators composing E3CI is specifically tailored to detect the extreme precipitation. Specifically, over 1981-2010, the cumulative value of daily precipitations exceeding the 95th percentile threshold has been computed as a base to identify monthly mean and standard deviation of the exceedance. Then, operationally, the values greater than 1 identify areas where the amount of precipitation beyond the 95th percentile, exceeds the monthly average of a value larger than the standard deviation. In a nutshell, the anomaly could be assumed more significant than the climatological interannual variability (assuming as proxy, the standard deviation).

This method is largely adopted in the literature and in the different regional and international operational dashboards to monitor the extreme precipitation dynamics. In this context, maps in Figure 1 refer to the month of November 2022: the areas in red shades represent those with indicator values larger than 1. In the left side of Figure 1, all the Italian regions have been included to provide a clear overview of the situation over the peninsula. Then, two maps about Campania and Emilia-Romagna region have been included to deepen the visualization of the most impacted areas over these two areas. In fact, E3CI values higher than 1 are very frequent over these two areas. And, since several health and economic damages due to precipitations have been observed by the local media for the month of November in these two regions, this entails a good representation of the reality captured by the E3CI index.

Impacts and Damages

Many anthropogenic factors have contributed over the years in a decisive way to the triggering or exacerbation of geo-hydrological risk in Italy. Intense precipitation contributes to a further increase in the hydraulic risk for small basins and the risk associated with surface landslides in areas with higher permeability soils. From 1991 to 2001 about 12,000 landslides and more than 1,000 floods have occurred in Italy. From 2000 to 2019, flood occurrences in Italy resulted in economic damages of almost $18.5 billion. As expected, the number of flood events and losses and damages varies by region, depending on the morphology and on the diverse adaptation measures implemented at the local scale to cope with flood and hydrogeological risks. According to the INFORMATION SYSTEM ON HYDROGEOLOGICAL CATASTROPHES of Italy, after Piedmont (17%), Veneto (11%), Lombardy (8.6%), Friuli-Venezia Giulia (7.5%) and Tuscany (6.8%), Emilia-Romagna (5.9%) and Campania (5.6%) are categorized among the regions with the highest number of events ever occurred in Italy.

In November, heavy rainfall triggered massive landslides and floods on several provinces of Emilia-Romagna and on the island of Ischia (Campania region). The effect of these occurrences were in fact reported via the natural disasters platform of the Centre for Research on the Epidemiology of Disasters (EM-DAT, CRED), and by the FloodList webpage. Since the first hours of 22 November, by looking at the Adriatic Coast, storm surge and high seas flooded coastal areas of Emilia-Romagna Region in the provinces of Forlì-Cesena, Ferrara, Rimini, and Ravenna. In particular, the tide associated with the storm surge was one of the highest registered and combined with very high waves, caused several meters of marine entry on the coast, especially between the municipalities of Ferrara and Ravenna. Several damages to the coast were reported and many houses near the beach were evacuated. Damage, partial or total, to the winter dune was observed all along the coast, with severity on the Ferrarese coast. Sea flooding affected Casalborsetti, Marina di Ravenna, Punta Marina, Lido Adriano and Lido di Savio, with damage to bathing establishments. In Rimini, flooding of the docks occurred due to rising waters in the Canal Harbour. No deaths or injuries were reported in this case.

In relation to Ischia – a volcanic island which lies some 30 km (19 miles) from Naples – on the first hours of Saturday 26th November 2022, local media reported 155mm of rain felt in parts of the island in just 6 hours. This is a record, since from around 20 years such an intense rainfall has not been recorded in the area. The number of manufacts built in high risk areas aggravated the local situation under heavy rainfall conditions. In fact, houses in northern parts of the island were damaged or destroyed as a torrent of mud, flood water and debris crashed down slopes of Mount Epomeo. Some areas were under mud and debris several metres deep. Dozens of vehicles were swept into the sea in areas of Casamicciola Terme. In term of losses, at least 167 people were evacuated, 12 victims have been recorded (https://blogs.agu.org/landslideblog/2022/11/28/casamicciola-1/).

References

  • Arpae Emilia-Romanga: Rapporto dell’evento meteorologico [link]
  • EMSR642: Storm in Emilia Romagna, Italy [link]
  • INFORMATION SYSTEM ON HYDROGEOLOGICAL CATASTROPHES of Italy [link]
  • Italy – 2 Dead, Several Feared Missing in Landslides and Floods on the Island of Ischia [link]
  • Italy – Floods and Storm Surge Prompt Rescues and Evacuations [link]
  • NOVEMBER 2022 | E3CI Update [link]
  • Ojeda, M. G. V., Di Sante, F., Coppola, E., Fantini, A., Nogherotto, R., Raffaele, F., & Giorgi, F. (2022). Climate change impact on flood hazard over Italy. Journal of Hydrology, 615, 128628 [link]
  • Precipitation, relative humidity and soil moisture for November 2022 [link]
  • Spano D., Mereu V., Bacciu V., Marras S., Trabucco A., Adinolfi M., Barbato G., Bosello F., Breil M., Chiriacò M. V., Coppini G., Essenfelder A., Galluccio G., Lovato T., Marzi S., Masina S., Mercogliano P., Mysiak J., Noce S., Pal J., Reder A., Rianna G., Rizzo A., Santini M., Sini E., Staccione A., Villani V., Zavatarelli M., 2020. “Analisi del rischio. I cambiamenti climatici in Italia”. DOI: 10.25424/CMCC/ANALISI_DEL_RISCHIO
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