Rainfall thresholds for shallow landslide occurrence in Calabria, southern Italy
In many areas, rainfall is the primary trigger of landslides. Determining the rainfall conditions responsible for landslide occurrence is important, and may contribute to saving lives and properties. In a long-term national project for the definition of rainfall thresholds for possible landslide occ...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-02-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | http://www.nat-hazards-earth-syst-sci.net/14/317/2014/nhess-14-317-2014.pdf |
| Summary: | In many areas, rainfall is the primary trigger of landslides. Determining the
rainfall conditions responsible for landslide occurrence is important, and
may contribute to saving lives and properties. In a long-term national
project for the definition of rainfall thresholds for possible landslide
occurrence in Italy, we compiled a catalogue of 186 rainfall events that
resulted in 251 shallow landslides in Calabria, southern Italy, from
January 1996 to September 2011. Landslides were located geographically using
Google Earth®, and were given a mapping and a
temporal accuracy. We used the landslide information, and sub-hourly rainfall
measurements obtained from two complementary networks of rain gauges, to
determine cumulated event vs. rainfall duration (<i>ED</i>) thresholds for
Calabria. For this purpose, we adopted an existing method used to prepare
rainfall thresholds and to estimate their associated uncertainties in central
Italy. The regional thresholds for Calabria were found to be nearly identical
to previous <i>ED</i> thresholds for Calabria obtained using a reduced set
of landslide information, and slightly higher than the <i>ED</i> thresholds
obtained for central Italy. We segmented the regional catalogue of rainfall
events with landslides in Calabria into lithology, soil regions, rainfall
zones, and seasonal periods. The number of events in each subdivision was
insufficient to determine reliable thresholds, but allowed for preliminary
conclusions about the role of the environmental factors in the rainfall
conditions responsible for shallow landslides in Calabria. We further
segmented the regional catalogue based on administrative subdivisions used
for hydro-meteorological monitoring and operational flood forecasting, and we
determined separate <i>ED</i> thresholds for the Tyrrhenian and the Ionian
coasts of Calabria. We expect the <i>ED</i> rainfall thresholds for
Calabria to be used in regional and national landslide warning systems. The
thresholds can also be used for landslide hazard and risk assessments, and
for erosion and landscape evolution studies, in the study area and in similar
physiographic regions in the Mediterranean area. |
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| ISSN: | 1561-8633 1684-9981 |