Application of the AHP method for prioritizing actions to reduce risk associated with gravitational mass movements in areas along the margins of watercourses of the city of Rio Branco, Brazil

Abstract

Problems related to gravitational mass movements at the margins of watercourses are present in different parts of the world, but in the Amazon, whose hydrological regime has unique characteristics, and whose socioeconomic situation may be considered underdeveloped, such problems come into sharp focus. Rotational landslides and creeps on the ground are present with high frequency and magnitude in several municipalities in the Western Amazon. Such processes act in association and annually cause significant losses and material damage. In this context, this study proposes the structuring of a decision-making process that aims to assist in the indication of critical areas, as well as proposing possible actions to mitigate risks. The criteria and procedures adopted for risk mapping in a portion of the urban center of Rio Branco-AC are described. Risk was measured, based on the multicriteria analysis of attributes related to the physical, anthropic environment and the characteristics of the processes considered. The hierarchical analysis method was the technique adopted to structure the risk assessment model, which was later integrated into the GIS environment, to allow spatial analysis. The results were presented in the form of cartograms, descriptive tables and graphs, and aim to help control the mapped risks.