Shallow landslide initiation on terraced slopes: inferences from a physically based approach

Abstract

In the last years, great efforts have been made to improve the assessment of the temporal and spatial occurrence of rainfall-induced shallow landslides. Therefore, in this paper we used a physically based stability model (TRIGRS) in order to reproduce the landslide event occurred in the Monterosso catchment (Cinque Terre, Eastern Liguria, Italy) on 25 October 2011. The input parameters of the numerical model have been evaluated taking into account the land-use setting and paying specific attention to the evaluation of the spatial variation of soil thickness on terraced areas. The resulting safety factor maps have been compared with the inventory map of the landslides triggered during the event. The simulation results, which have been obtained also considering four different spatial resolutions of the digital terrain model, emphasize the influence of land use in shallow landslide occurrence and indicate the importance of a realistic spatial variation of soil thickness to enhance the reliability of the model. Finally, different triggering scenarios have been defined using hourly rainfall values statistically derived from historical data. The results indicate the proneness of the area to shallow landsliding, given that rainfall events with a relatively low return period (e.g. 25 years) can trigger numerous slope failures.

Investigation on Farmland Abandonment of Terraced Slopes Using Multitemporal Data Sources Comparison and Its Implication on Hydro-Geomorphological Processes

“…These observations testify that terraced areas are highly susceptible to slope instabilities in case of extreme rainfall. This is in agreement with the evidences reported by other researches performed both in the study area [11,59,[84][85][86][87][88][89][90] and in other terraced environments around the world [58,[91][92][93]. As reported in technical literature, several factors can influence the occurrence of slope instabilities in terraced systems [58].…”

Hillslope degradation in representative Italian areas: Just soil erosion risk or opportunity for development?

“…As evidenced in the Cinque Terre area, on terraced slopes, the combined effect of land use changes and of single extreme rainfall can accelerate considerably hillslope degradation. In this area, the strong abandonment of agricultural practices occurred since 1950s resulted in the most important predisposing factor for erosion and shallow landslide phenomena (Brandolini et al, ; Cevasco et al, ; Schilirò, Cevasco, Esposito, & Scarascia Mugnozza, ). This has been also recently confirmed by landslide susceptibility modelling (Bordoni et al, ; Galve et al, ; Persichillo et al, ; Persichillo et al, ).…”

Empirical and Physically Based Thresholds for the Occurrence of Shallow Landslides in a Prone Area of Northern Italian Apennines

“…In particular, a pore-water pressure equal to −993 kPa was assumed, according to the field measurements reported in Bordoni et al [24,47]. This modeling approach was already implemented for the estimation of time series of soil hydrological parameters in other Italian regions prone to shallow landslides [53,62], obtaining a good estimation of the initial pore-water pressure conditions of a triggering event.…”