Comparison of the implementation of rock engineering system and analytic hierarchy process methods, upon landslide susceptibility mapping, using GIS: a case study from the Eastern Achaia County of Peloponnesus, Greece

As landslides are very common in Greece, causing serious problems to the social and economic welfare of many communities, the implementation of a proper hazard analysis system will help the creation of a reliable susceptibility map. Τhis will help local communities to define a safe land use and urban development. The purpose of this study is to compare the implementation of two semi-quantitative landslide assessment approaches, using landslide susceptibility maps compiled in a GIS environment. The compared methods are rock engineering system (RES) and the analytic hierarchy process (AHP). For the landslide susceptibility analysis, the Northeastern part of the Achaia County was examined. This area suffers from many landslides, because of its neighborhood with the tectonically active Corinthian Gulf and its geological setting (Neogene sediments, flysch and other bedrock formations, with local overthrusts). Ten parameters were used in both methodologies, and each one was separated into five categories ranging from 0 to 4, representing their specific conditions derived from the investigation of the landslides in the western part of the study area (ranking area). A layer map was generated for each parameter, using GIS, while the weighting coefficients of each methodology were used for the compilation of RES and AHP final maps of the eastern part of the study area (validating area). By examining these two maps, it is revealed that even though both correctly show the landslide status of the second site, the RES map reveals a better behavior in the spatial distribution of the various landslide susceptibility zones.