Rainfall thresholds for the forecasting of landslide occurrence at regional scale

This paper concerns a regional scale warning system for landslides that relies on a decisional algorithm based on the comparison between rainfall recordings and statistically defined thresholds. The latter were based on the total amount of rainfall, which was cumulated considering different time intervals: 1-, 2- and 3-day cumulates took into account the critical rainfall influencing shallow movements, whilst a variable time interval cumulate (up to 240 days) was used to consider the triggering of deep-seated landslides in low permeability terrains. A prototypal version of the model was initially set up to define statistical thresholds. Then, thresholds were calibrated using a database of past georegistered and dated landslides. A validation procedure showed that the calibration highly improves the results and therefore the model was integrated in the regional warning system of Emilia Romagna (Italy) for civil protection purposes. The proposed methodology could be easily implemented in other similar regions and countries where a sufficiently organised meteorological network is present.

[1]  G. Vai,et al.  Anatomy of an orogen : the Apennines and adjacent Mediterranean basins , 2001 .

[2]  F. Noverraz,et al.  Influence of climate change on large landslides : assessment of long-term movements and trends , 2001 .

[3]  M. Rosi,et al.  Civil protection preparedness and response to the 2007 eruptive crisis of Stromboli volcano, Italy , 2009 .

[4]  Mario Floris,et al.  Recent changes in rainfall characteristics and their influence on thresholds for debris flow triggering in the Dolomitic area of Cortina d'Ampezzo, north-eastern Italian Alps , 2010 .

[5]  Salvatore Gabriele,et al.  The performance of the two-component extreme value distribution in regional flood frequency analysis , 1988 .

[6]  Landscape dynamics risk management in Northern Apennines (Italy) , 1970 .

[7]  Fausto Guzzetti,et al.  Rainfall thresholds for the possible occurrence of landslides in Italy , 2010 .

[8]  Kyoji Sassa,et al.  The influence of intense rainfall on the activity of large-scale crystalline schist landslides in Shikoku Island, Japan , 2005 .

[9]  John L. Innes,et al.  Debris flows , 1983 .

[10]  Mauro Fiorentino,et al.  Two‐Component Extreme Value Distribution for Flood Frequency Analysis , 1984 .

[11]  Nicola Casagli,et al.  Rainfall patterns and related landslide incidence in the Porretta-Vergato region, Italy , 2004 .

[12]  M Koster.  DEVELOPMENT AND APPLICATION OF COMPUTER TECHNIQUES TO ENVIRONMENTAL STUDIES , 2002 .

[13]  Roberto Rudari,et al.  Towards a definition of a real-time forecasting network for rainfall induced shallow landslides , 2009 .

[14]  M. Rossi,et al.  The rainfall intensity–duration control of shallow landslides and debris flows: an update , 2008 .

[15]  Franco Siccardi,et al.  A reflection about the social and technological aspects in flood risk management – the case of the Italian Civil Protection , 2010 .

[16]  M. Terlien.  The determination of statistical and deterministic hydrological landslide-triggering thresholds , 1998 .

[17]  Fausto Guzzetti,et al.  Landslide fatalities and the evaluation of landslide risk in Italy , 2000 .

[18]  R. Olea.  Geostatistics for Natural Resources Evaluation By Pierre Goovaerts, Oxford University Press, Applied Geostatistics Series, 1997, 483 p., hardcover, $65 (U.S.), ISBN 0-19-511538-4 , 1999 .

[19]  N. Caine,et al.  The Rainfall Intensity - Duration Control of Shallow Landslides and Debris Flows , 1980 .

[20]  Fausto Guzzetti,et al.  Rainfall induced landslides in December 2004 in south-western Umbria, central Italy: types, extent, damage and risk assessment , 2006 .

[21]  G. Wieczorek,et al.  LANDSLIDES: INVESTIGATION AND MITIGATION. CHAPTER 4 - LANDSLIDE TRIGGERING MECHANISMS , 1996 .

[22]  Pietro Aleotti,et al.  A warning system for rainfall-induced shallow failures , 2004 .

[23]  M. Baucus.  Transportation Research Board , 1982 .

[24]  Giovanni B. Crosta,et al.  Regionalization of rainfall thresholds: an aid to landslide hazard evaluation , 1998 .

[25]  R. H. Campbell,et al.  Debris flows originating from soil slips during rainstorms in Southern California* , 1974, Quarterly Journal of Engineering Geology.