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| Titel |
Changes in the occurrence of rainfall-induced landslides in Calabria, southern Italy, in the 20th century |
| VerfasserIn |
S. L. Gariano, O. Petrucci, F. Guzzetti |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 15, no. 10 ; Nr. 15, no. 10 (2015-10-13), S.2313-2330 |
| Datensatznummer |
250119720
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| Publikation (Nr.) |
 copernicus.org/nhess-15-2313-2015.pdf |
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| Zusammenfassung |
| Only a few studies have investigated the geographical and temporal
variations in the frequency and distribution of rainfall-induced landslides,
and the consequences of the variations on landslide risk. Lack of
information limits the possibility to evaluate the impact of environmental
and climate changes on landslide frequency and risk. Here, we exploit
detailed historical information on landslides and rainfall in Calabria,
southern Italy, between 1921 and 2010 to study the temporal and the
geographical variation in the occurrence of rainfall-induced landslides and
in their impact on the population. We exploit a catalogue with information
on historical landslides from June 1920 to December 2010, and daily rainfall
records obtained by a network of 318 rain gauges in the same period, to
reconstruct 448 493 rainfall events (RE). Combining the rainfall and the
landslide information, we obtain a catalogue of 1466 rainfall events with
landslides (REL), where an REL is the occurrence of one or more landslide
during or immediately after a rainfall event. We find that (i) the
geographical and the temporal distributions of the rainfall-induced
landslides have changed in the observation period, (ii) the monthly
distribution of the REL has changed in the observation period, and (iii) the
average and maximum cumulated event rainfall that have resulted in
landslides in the recent 30-year period 1981–2010 are lower than the
rainfall necessary to trigger landslides in previous periods, whereas the
duration of the RE that triggered landslides has remained the same. We
attribute the changes to variations in the rainfall conditions and to an
increased vulnerability of the territory. To investigate the variations in
the impact of REL on the population, we compared the number of REL in each
of the 409 municipalities in Calabria with the size of the population in
the municipalities measured by national Censuses conducted in 1951, 1981,
and 2011. We adopted two strategies; the first strategy considered impact as
IREL = #REL / P, and the second strategy measured impact as
RREL = #REL × P, where #REL is the total number of REL
in a period, and P is the size of the population in the same period and
geographical area. The analysis has revealed a complex pattern of changes in
the impact of rainfall-induced landslides in Calabria in the recent past,
with areas where IREL and RREL have increased, and other areas where
they have decreased. Municipalities where IREL has increased are mainly
in the mountains, and municipalities where RREL has increased are mainly
along the coasts. The complexity of the changes in the frequency and impact
of rainfall-induced landslides observed in Calabria suggests that it remains
difficult and uncertain to predict the possible variations in the frequency
and impact of landslide in response to future climatic and environmental
changes. |
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