Landslide risk mapping in an urban area of the city of Natal, Brazil

Landslides are part of the natural processes of Earth’s surface dynamic, which could be accelerated or triggered by anthropic interference. Inadequate occupation of areas highly susceptible to landslide processes is the principal cause of accidents on Brazilian urban slopes, especially those occupied by settlements and slums. In Natal, Rio Grande do Norte state, Brazil, the existence of areas with steep and densely occupied slopes makes the municipality susceptible to landslides. In this context, the present study aimed to map the risk of landslides in an urban area located in the city of Natal. Using the quali-quantitative model proposed by Faria (2011), adapted for the conditions of the study area, which applies a multicriteria analytical hierarchy process (AHP) to a Geographic Information System (GIS), 11 risk indicators were submitted to pairwise comparisons by 10 risk management specialists in order to determine the relative importance (weighting) for each of these factors as a function of their contribution to the risk. The weightings obtained were combined to produce the final risk map of the study area, using a map algebra framework. The results show the existence of a critical risk for the resident population, primarily related to the possibility of a landslide, with potentially negative economic, environmental, and mainly social impacts.