Application of the Analytic Hierarchy Process to landslide hazard mapping in urban areas

Abstract

The method of hazard mapping of landslides in urban areas adopted by the Ministério das Cidades is the most currently used method in Brazil. In order to make it more systematic and to reduce the subjectivity in comparing and ranking hazardous areas, but without changing its fundamental approach, this paper proposes to incorporate the Analytic Hierarchy Process (AHP) into the analysis. To validate this proposal, this approach was tested in areas of landslide risk in the municipality of São Sebastião (SP), previously mapped by the Geological Institute of the Geological Institute of the Environmental Secretariat of São Paulo State (IG/ SMA/SP), according to the traditional approach, i.e., without the systematic use of AHP. The results of the hazard mapping by the IG for one of these areas (Vila Baiana), exemplified in this work, were more conservative than those obtained using AHP. The application of AHP reduced the subjectivity and showed the ease and convenience in weighting the hazard indicators for hazard ranking. An analysis of the opinions of three experts in the parity judgment of landslide hazard indicators showed no discrepancies in the ranking of hazard.