5. Conclusions

Rainfall is the main trigger of mass movements in tropical regions, so the evaluation of its effect on stability becomes increasingly important, leading to the generation of increasingly complex models.

There are several proposals to consider the effect of rainfall on slope stability, empirical models such as failure thresholds, and physically based analytical models. The approximate solution of these analytical models is more used today. A probabilistic approach such as the one presented in this work allows to incorporate in the analysis the different sources of uncertainty that affect the behavior of the infiltration in soils and permit evaluating the effect of the rainfall infiltration processes on the landslide hazard assessment of unsaturated soils in tropical mountainous regions.

It was observed that in the soils considered, the variation of the wetting front, in rain conditions such as those shown, only affects the most superficial layer of the soil, reason why the effect of the rains mainly generates faults of the shallow type.

The rainfall threshold approach is an efficient methodology to evaluate shallow landslide with respect to physically based approach (wetting front progress), because it requires less processing time, characterization soils, laboratory tests, and elaborated methodological approaches.
