Land Use Change Scenarios and Landslide Susceptibility Zonation: The Briga Catchment Test Area (Messina, Italy)

Landslides spatial distribution and frequency are the consequence of different meteorological and environmental conditions including morphological, hydrological, lithology the land use settings. In this work we have attempted to evaluate the influence of land use change on landslide spatial distribution occurrence (susceptibility) for a portion of the Briga catchment, located along the Ionian coast of Sicily, Italy. On 1 October 2009, the area was hit by a high intensity rainfall event that triggered abundant slope failures, and resulted in widespread erosion and deposition of debris along ephemeral drainage channels. After the storm, an accurate event landslide inventory map was made for the catchment and a pre-event landslide map was prepared using aerial photographs. Moreover two different land use maps were realized, the first was obtained through a semi-automatic classification of digitized aerial photographs acquired in 1954, the second through the combination of supervised classifications of two QuickBird images acquired in 2006 and 2009. Using the available thematic data, we have prepared susceptibility zonation through multivariate statistical models exploiting the 2009 event landslides as grouping variable and simple morphological and 2009 land use data as explanatory variables. To evaluate the influence of land use change on the susceptibility zonation, the same discriminant models were applied to different land use distribution including the 1954 land use map. Differences in the landslide susceptibility maps were analysed to understand how land use change affects the landslide occurrence.