Soil Saturation and Stability Analysis of a Test Site Slope Using the Shallow Landslide Instability Prediction (SLIP) Model

It is well-known that the degree of saturation
is a soil state condition able to represent the
hydrological response of a shallow soil to weather
conditions. One of the oldest models that referred on
the degree of saturation to carry out the slope stability
analysis at different scales, was the Shallow Landslide
Instability (SLIP) Model. This paper shows how the
SLIP model can be used to derive a simplified method
to estimate multiple seasonal cycles of the mean
degree of saturation of soil and to carry out the timevarying
stability analysis of a test site slope. The
simplified method to assess the degree of saturation
uses easily available climatic data, such as air
temperature and rainfall depth, and is validated
through the comparison with long-term field measurements
on a slope in Canneto Pavese, northern Italy.
The SLIP model is also applied to obtain the safety
factor of the slope, that was subjected to a rainfallinduced
shallow landslide during the field monitoring
period. Comparisons between field measurements and
model outputs are used to validate the capability of the
model of predicting both the mean degree of saturation
of the topsoil and the observed unstable condition.