Remarks on the Role of Landslide Inventories in the Statistical Methods Used for the Landslide Susceptibility Assessment

In this work, the role of different landslide inventories in susceptibility assessment was
evaluated using a non linear regression technique, namely the generalized additive model
(GAM).The investigation was carried out in three study areas: the Versa catchment
(Oltrepò Pavese, Southern Lombardy, Italy), the Vernazza catchment (Cinque Terre,
Eastern Liguria, Italy) and the Pogliaschina catchment (Vara Valley, Eastern Liguria, Italy).
Two landslide inventories related to the 2009 and 2013 rainfall events were taken into
account in the Versa catchment, whereas two landslide inventories (referred to the same
2011 rainfall event) which differ for methods of detection and criteria adopted for the
landslide mapping were considered in the Vernazza and Pogliaschina catchments. The
predictive performance of GAM for each landslide inventory was evaluated. The results
related to different inventories were compared. The results show that the predictive
capability of the model and the landslide susceptibility are significantly influenced by the
type of landslide inventory. Thus, the work highlights that a standard criterion for preparing
inventories should be adopted in order to produce landslide susceptibility assessment as
reliable as possible.