The Effect of Morphometry, Land-use and Lithology on Landslides Susceptibility: An Exploratory Analysis

GIS features provide simple and useful tools for landslides susceptibility and hazard studies, allowing the identification and the quantification of predisposing factors, and their relative importance. In lithologically homogeneous areas, the most influent factor of landslides is slope morphometry, in particular inclination, height and form. Moreover, within a hydrographic basin, landslides are coupled with drainage network. In fact landslides density and drainage density are positively correlated. Furthermore, human activity strongly influences the development of landslides. In our previous works, we introduced MSI (Morphometric Slope Index) as general index for slope morphometry, combining the main linear and areal morphometric features (area, form, length, inclination, width). Its formula is: MSI = A(3D)/A(2D) . L . R-c (where A(3D) is the three-dimensional area of the slope, A(2D) is its plan area, L is the slope length and R-c is the circularity ratio). We tested MSI as driver of different erosion landforms, demonstrating its influence in determining, on the one hand, the development and the final arrangement of calanchi drainage network (the typical Italian badlands), and, on the other hand, the erosion processes within them, mainly gullies and landslides. The present study is an exploratory application of this index to landslides susceptibility, aimed to analyze the combined effect of slope morphometry (summarized in MSI), lithology and land-use on the distribution of landslides in small catchments. The study is located in the Italian periadriatic foredeep, in the Abruzzo Region. This study has reinforced our perspective about the validity of the application of the techniques of geomorphometric analysis to the landslides susceptibility. Especially we consider this approach an efficient tool to summarize different controlling factors.