Modeling regional initiation of rainfall-induced shallow landslides in the eastern Umbria Region of central Italy

We model the rainfall-induced initiation of shallow landslides over a broad region using a deterministic approach, the Transient Rainfall Infiltration and Grid-based Slope-stability (TRIGRS) model that couples an infinite-slope stability analysis with a one-dimensional analytical solution for transient pore pressure response to rainfall infiltration. This model permits the evaluation of regional shallow landslide susceptibility in a Geographic Information System framework, and we use it to analyze susceptibility to shallow landslides in an area in the eastern Umbria Region of central Italy. As shown on a landslide inventory map produced by the Italian National Research Council, the area has been affected in the past by shallow landslides, many of which have transformed into debris flows. Input data for the TRIGRS model include time-varying rainfall, topographic slope, colluvial thickness, initial water table depth, and material strength and hydraulic properties. Because of a paucity of input data, we focus on parametric analyses to calibrate and test the model and show the effect of variation in material properties and initial water table conditions on the distribution of simulated instability in the study area in response to realistic rainfall. Comparing the results with the shallow landslide inventory map, we find more than 80% agreement between predicted shallow landslide susceptibility and the inventory, despite the paucity of input data.

[1]  Jon J. Major,et al.  Rainfall, ground-water flow, and seasonal movement at Minor Creek landslide, northwestern California: Physical interpretation of empirical relations , 1987 .

[2]  Russell H. Campbell,et al.  Soil slips, debris flows, and rainstorms in the Santa Monica Mountains and vicinity, southern California , 1975 .

[3]  D. Salciarini,et al.  The debris flow hazard in the Lagarelle Creek in the eastern Umbria region, central Italy , 2005 .

[4]  Richard M. Iverson,et al.  Landslide triggering by rain infiltration , 2000 .

[5]  Relazioni fra movimenti di versante e fenomeni tettonici nell'area del M. Coscerno-M di Civitella, Valnerina (Umbria) , 1993 .

[6]  Rex L. Baum,et al.  Rainfall characteristics for shallow landsliding in Seattle, Washington, USA , 2006 .

[7]  J. Godt,et al.  Characteristics of debris flow events in eastern Umbria, central Italy , 2006 .

[8]  J. Bear.  Dynamics of Fluids in Porous Media , 1975 .

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

[10]  R. Sidle,et al.  A distributed slope stability model for steep forested basins , 1995 .

[11]  P. Reichenbach,et al.  Regional hydrological thresholds for landslides and floods in the Tiber River Basin (central Italy) , 1998 .

[12]  Mark E. Reid.  A Pore-Pressure Diffusion Model for Estimating Landslide-Inducing Rainfall , 1994, The Journal of Geology.

[13]  F. Melone,et al.  Spatial Distribution of Pre-Warm Front Rainfall in the Mediterranean Area , 1988 .

[14]  K. Terzaghi.  Theoretical Soil Mechanics , 1943 .

[15]  Robert A. Crovelli,et al.  Probabilistic Assessment of Precipitation-Triggered Landslides Using Historical Records of Landslide Occurrence, Seattle, Washington , 2004 .

[16]  F. Guzzetti,et al.  Debris-flow phenomena in the Central Apennines of Italy , 1991 .

[17]  W. Haneberg.  Pore Pressure Diffusion and the Hydrologic Response of Nearly Saturated, Thin Landslide Deposits to Rainfall , 1991, The Journal of Geology.

[18]  J. C. Jaeger,et al.  Fundamentals of rock mechanics , 1969 .

[19]  D. Montgomery,et al.  A physically based model for the topographic control on shallow landsliding , 1994 .

[20]  Rex L. Baum,et al.  Modeling time-dependent areal slope stability , 2004 .

[21]  W. Z. Savage,et al.  TRIGRS - A Fortran Program for Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis, Version 2.0 , 2002 .

[22]  M. Reid.  SLOPE INSTABILITY CAUSED BY SMALL VARIATIONS IN HYDRAULIC CONDUCTIVITY , 1997 .

[23]  L. Matteo,et al.  Risorse idriche sotterranee e loro gestione: il caso dell'ATO2 Umbria (Umbria Meridionale) , 2005 .

[24]  Rex L. Baum,et al.  A model for spatially and temporally distributed shallow landslide initiation by rainfall infiltration , 2003 .

[25]  Andrea G. Fabbri,et al.  Validation of Spatial Prediction Models for Landslide Hazard Mapping , 2003 .

[26]  J. C. Jaeger,et al.  Conduction of Heat in Solids , 1952 .