Análise multicritério em sinergia com a álgebra de mapas para avaliar a suscetibilidade a movimentos de massa no Maciço de Baturité

Abstract

The State of Ceará, even though it is mainly characterized by the hinterland depression, has humid enclaves that have different hydroclimatic characteristics associated with high declivity, with the Massif de Baturite being one of these outstanding places. In this region, mass movements are common, mainly of translational and rotational landslides, in addition to falling blocks, which are phenomena that modify the landscape and which may, by chance, cause damage and / or accidents, requiring a more adequate assessment. Thus, the objective of this research was to analyze the probability of occurrences of mass movements in the Baturité Massif, with the application of multicriteria analysis in a GIS environment (Geographic Information Systems) associated with map algebra. This methodology consists of the integration of the chosen variables and the conditioning factors, so that the final product comprises in a susceptibility map. Five variables were chosen (geomorphology, pedology, slope, slope orientation and rainfall) and two susceptibility maps were developed, one for landslides and the other for falls from blocks, this being movements that have some distinct characteristics. Thus, the main results pointed out that the most humid region of the Massif de Baturite (dissected wet slope), which has high slopes and deep mantles of weathering, has a degree of susceptibility “Very High” to landslides, followed by the region to the leeward (dry dissected strand), classified as “High” susceptibility. Regarding block falls, the dry dissected slope, rocky domes, ridges and inselbergs showed a “Very High” degree of susceptibility, due to the high declivity, less pedological formation, in addition to the action of weathering agents on the exposed rock, followed by wet dissected strand, classified with “High” susceptibility. As a form of validation of the models developed by map algebra, the scars of the occurrences mapped in the field were superimposed, these appearing coincidentally in the high susceptibility classes of the elaborated maps.