Abstract
Precipitation is one of the main landslides triggering factors because the amount of infiltrated water into the ground causes changes in pore pressure due to the decrease in suction or the rising water table level. In this paper we estimated the return period of landslides from a rainfall stochastic behavior. Using rainfall intensity and duration probability density functions (pdf) and Philip’s infiltration model, the pdf of water infiltrated volume into the soil was obtained. Then, assuming the soil reaches saturation, the pdf of depth wetting front (zw) was obtained. Finally, with zw and the Mohr-Coulomb rupture criteria, the pdf of the Factor of Safety (FS) was determined. Subsequently, landslide occurrence was analyzed under different hydroclimatic scenarios, such as dry and wet seasons and El Nino Southern Oscillation (ENSO) phases. The occurrence of shallow landslides depends more on intensity storm than duration storm, and they are more likely to happen during La Nina phase than during El Nino phase because both storm duration and storm intensity tend to increase.
Highlights
Most landslides occur on rainiest months [1], showing the close relation between the hydroclimatic conditions as a triggering factor and the occurrence of landslides.Landslides triggered by rainfall, known as “soil slip”, are characterized for having superficial failure surfaces and parallels to the slope face
Statistical models have been used from different approaches, among which are the definition of critical thresholds that relate rainfall events intensity and duration with landslides occurrence (e.g. [8,9,10,11,12]), and the search for relations between landslide geometrical characteristics and their frequency of occurrence for different climatological scenarios (e.g. [13,14,15,16])
The stability of a hypothetical slope has been analyzed under different climate scenarios, considering that
Summary
Most landslides occur on rainiest months [1], showing the close relation between the hydroclimatic conditions as a triggering factor and the occurrence of landslides. Landslides triggered by rainfall, known as “soil slip”, are characterized for having superficial failure surfaces (between 1 and 3 meters) and parallels to the slope face. This type of movements are due to changes on soil pore pressure when a wetting front product of infiltration advances [2]. The problem with rainfall as a triggering factor has been approached using physical and statistical models. Statistical models have been used from different approaches, among which are the definition of critical thresholds that relate rainfall events intensity and duration with landslides occurrence Through deterministic models of infiltration, wetting front depth and factor of safety, the rainfall probability density functions (pdf) was transformed into pdf of FS
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