Inventário de movimentos de massa na bacia hidrográfica do rio Mascarada/RS

Abstract

Mass movements inventories play a key role to the understanding of watershed dynamics. The alteration of this dynamics occurs in the moment of failure and after it due the erosion when precipitation hits the uncovered soil at the mass movement scars. Thus, this paper has characterized these mass movements, which are classified as landslides, occurred in Mascarada´s river basin through different geomorphological parameters, as slope and curvature, and comparing shape parameters against different methodologies to determine the evaluation area. The proposed shape parameters Percentage of affected area (PAA), Drainage density of scars (Ddc) and Density of scars (Dcic) were evaluated against total area of Mascarada´s river basin, against two sub-basins and against a proposed “Area of influence”. 407 scars were mapped with an area of 2,2 km², a mean slope of 36,1° and all scars are in convergent areas. The evaluation of shape forms showed that “area of influence” improved the understanding of this mass movements magnitude. Thus, the elaboration of mass movement inventories with reliable methodologies can provide important information for the natural disaster management.