GIS Methodology to Assess Landslide Susceptibility: Application to a River Catchment of Central Italy

This paper illustrates a geographic information system (GIS) supported methodology for the assessment
of landslide susceptibility. The methodology involves four operational steps:
survey, site analysis, macro-
area analysis
and
susceptibility analysis
. The
Survey
includes the production (or acquisition) of a large-scale
litho-technical map, a large-scale geomorphological map, a detailed inventory of past and present land-
slide events, and a high resolution DTM (Digital Terrain Model.
Site analysis
leads to the definition of
discriminating parameters
(commonly, lithological and morphometric conditions necessary but not suffi-
cient to trigger a landslide of a given type) and
predisposing factors
(conditions that worsen slope stability
but are not sufficient to trigger a landslide of a given type in the absence of
discriminating parameters
). The
different
predisposing factors
are subdivided into classes, whose intervals are established by descriptive,
statistical analysis of landslide inventory data. A numerical index, based on the frequency of landslide
occurrence, quantifies the contribution of each class to slope instability.
Macro-area analysis
includes the generation of
Litho-Morphometric Units
(LMU) by overlaying
discrimina-
ting parameters
, manual drawing of LMU envelopes (
macro-areas
), generation of
predisposing factor
maps
from the spatial distribution of
predisposing factors
, and heuristic weighting of
predisposing factor
indices.
Susceptibility analysis
includes the generation of
Homogeneous Territorial Units
(HTU) by overlaying
macro-
areas
and
predisposing factor maps
, and the application of a
susceptibility function
to the different HTU. The
resulting values are normalized before the generation of the
landslide susceptibility maps
. The methodo-
logy has been applied to the Fiumicino River catchment, located in the western side of Latium Apennine
(Central Italy) between 200 and 1300 m a.s.l. and developed on Late Miocene calcarenites, sandstones
with clay intercalations, and marls. The resulting
landslide susceptibility maps
will be employed in envi-
ronmental management. They also represent the preliminary step for the assessment of landslide hazard
and risk

ABBATTISTA, F., D’AGOSTINO, G., DELMONACO, G., DI FILIPPO, L., FALCONI, L., LEONI,
G., MARGOTTINI, C., PUGLISI, C., ROMANO, P. and SPIZZICHINO, D. (2005) Assessment of
landslide susceptibility: application to rapid flows at Cervinara (Southern Italy), Geologia Tecnica e
Ambientale, 1/2005, 25–40.
CARRARA, A., GUZZETTI, F., CARDINALI, M. and REICHENBACH, P. (1999) Use of GIS techno-
logy in the prediction and monitoring of landslide hazard, Natural Hazards, 20, 2-3, 117–135.
CASAGLI, N., CATANI, F., PUGLISI, C., DELMONACO, G., ERMINI, L. and MARGOTTINI, C.
(2004) An inventory-based approach to landslide susceptibility assessment and its application to the
Virginio River basin, Italy, Environmental and Engineering Geoscience, 10, 203–216.
CIPOLLARI, P. and COSENTINO, D. (1992) La linea Olevano-Antrodoco: contributo della biostra-
tigrafia alla sua caratterizzazione cinematica, Studi Geologici Camerti, vol. spec. CROP 11, 1991/2,
143–150.
GUZZETTI, F., CARRARA, A., CARDINALI, M. and REICHENBACH, P. (1999) Landslide hazard
evaluation: a review of current techniques and their application in a multi-scale study, Central Italy,
Geomorphology, 31, 1-4, 181–216.
VARNES, D. J. (1978) Slope movements types and processes, Transportation Research Board, National
Academy of Sciences, Special Report, Washington D.C., pp. 20–47.
VARNES, D. J. (1984) Landslide Hazard Zonation - a review of principles and practice, IAEG Commis-
sion on Landslides, UNCESCO Paris, 63 pp.