Avaliação de suscetibilidade à movimentos de massa, utilizando as variáveis morfométricas, para as serras da porção sul do Maciço Central do Ceará

Abstract

In recent decades, natural disasters caused by landslides have caused many deaths and economic losses in Brazil and as worldwide. Susceptibility maps to mass movements have been used to indicate areas susceptible to these phenomena in mountainous regions, allowing better planning of the land use. This paper presents susceptibility maps to mass movements, based on morphometric variables natural and environmental analysis, in order to make an evaluation multicriterial about susceptibility to this kind of movement. Remote sensing products (Landsat 8 and TOPODATA) and some pre-existing maps, (like geology, pedologic and vegetation maps) were used, using map algebra in GIS environment, to generate morphological susceptibility maps, environmental and natural to mass movements. The calculation involved values, where the infl uences of the variables and the values of the units were analyzed by Delphi and AHP methods. The results allowed the identifi cation of small diff erences in susceptibilities values for five defined classes (Very Low, Low, Medium, High, and Very High). These small diff erences occurred between the morphological and environmental maps, which refl ected the weight of human actions on the assigned infl uence values. The CASMO (Morphological Susceptibility Map) presents the greater variations in relation to the other maps, due to the diff erence between the resolutions of the analyzed products. We conclude that the methods employed were effi cient for this kind of assessment and that the CASAM map (Environmental Susceptibility Map) and CASNA map (Natural Susceptibility Map) obtaining better results when analyzed in 1:25,000 scale.