GIS-based landslide susceptibility mapping using analytical hierarchy process: a case study in Porto Alegre Municipality, Brazil

Landslides are one of the most devastating disasters among all natural hazards in Brazil, with nearly 3,355 fatalities between 1988 and 2013. Apart from the loss of lives, they also cause substantial economic losses. As an example, the mass movements that occurred in 2011 in Rio de Janeiro resulted in US$ 2.8 billion in damage. Thus, in order to mitigate these hazards, it is essential to map the landslide susceptibility. A variety of techniques have been proposed to assess the susceptibility. Deterministic approaches require geotechnical data that are not readily available in lesser developed countries. Likewise, statistical methods demands detailed landslide inventories, which are still scarce in Brazil. On the other hand, heuristic approaches, based on multiple criteria decision making (MCDM) techniques, allow the use of existing data and are relatively easy to apply. These methods can deal with the knowledge arising from the participation of many decision makers as well as a large number of criteria. In this sense, the main goal of this research was to develop and apply a methodology for landslide susceptibility mapping in data scarce areas, using MCDM techniques. The approach was tested in Porto Alegre municipality (476.3 km2), which is the most affected region in Rio Grande do Sul State, southern Brazil.