Rainfall events with shallow landslides in the Entella catchment, Liguria, northern Italy
<p>In recent decades, the Entella River basin, in the Liguria Apennines, northern Italy, was hit by numerous intense rainfall events that triggered shallow landslides and earth flows, causing casualties and extensive damage. We analyzed landslide information obtained from different sources...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-09-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://www.nat-hazards-earth-syst-sci.net/18/2367/2018/nhess-18-2367-2018.pdf |
| Summary: | <p>In recent decades, the Entella River basin, in the
Liguria Apennines, northern Italy, was hit by numerous intense rainfall
events that triggered shallow landslides and earth flows, causing casualties
and extensive damage. We analyzed landslide information obtained from
different sources and rainfall data recorded in the period 2002–2016 by
rain gauges scattered throughout the catchment, to identify the event rainfall
duration, <i>D</i> (in h), and rainfall intensity, <i>I</i> (in mm h<sup>−1</sup>), that
presumably caused the landslide events. Rainfall-induced landslides affected
the whole catchment area, but were most frequent and abundant in the central
part, where the three most severe events hit on 23–24 November 2002,
21–22 October 2013 and 10–11 November 2014. Examining the timing and location of
the slope failures, we found that the rainfall-induced landslides occurred
primarily at the same time or within 6 h from the maximum peak
rainfall intensity, and at or near the geographical location where the
rainfall intensity was largest. Failures involved mainly forested and
natural surfaces, and secondarily cultivated and terraced slopes, with
different levels of maintenance. Man-made structures frequently characterize
the landslide source areas. Adopting a frequentist approach, we define the
event rainfall intensity–event duration (ID) threshold for the possible
initiation of shallow landslides and hyper-concentrated flows in the Entella
River basin. The threshold is lower than most of the curves proposed in the
literature for similar mountain catchments, local areas and single regions
in Italy. The result suggests a high susceptibility to rainfall-induced
shallow landslides of the Entella catchment due to its high-relief
topography, geological and geomorphological settings, meteorological and
rainfall conditions, and human interference. Analysis of the antecedent
rainfall conditions for different periods, from 3 to 15 days, revealed that
the antecedent rainfall did not play a significant role in the initiation of
landslides in the Entella catchment. We expect that our findings will be
useful in regional to local landslides early warning systems, and for
land planning aimed at reducing landslide risk in the study area.</p> |
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| ISSN: | 1561-8633 1684-9981 |