Aplicação do modelo SHALSTAB no mapeamento de áreas susceptíveis à ocorrência de movimentos de massa, na bacia do rio Marumbi, Serra do Mar, Paraná

Abstract

This paper presents the application of the SHALSTAB (Shallow Landsliding Stability) Model in a quantitative approach to mapping areas susceptible to the occurrence of mass motion at the Marumbi River’s basin strands, Serra do Mar, Paraná. This slope stability model gathers pedological, geomorphological and hydrological data in the prevision of unstable areas which will determinate the rainfall needed to trigger extreme events. Also, it was possible to compare results obtained from other methodology through the Factor of Safety (SF) map elaborated in another author’s research, which uses a mathematical model that has base in the distribution of forces acting on a slope of finite extension, regarding as variables the land’s inclination, soil’s physical and mechanical properties, water presence, vegetation influence. The results founded were satisfactory and they show that both methodologies are efficient to identification of unstable areas, once the landslides occurred in the basin in previously years were identified in this area from both methods. The SHALSTAB presented results more accurate, once the area’s dimension considered unstable got more close to the cataloged areas in previously events of mass motion in the basin. Other important SHALSTAB’s result was the hydrologic event’s quantification needed to occur landslides. The accuracy’s level the techniques applied is directly related to geometric accuracy, detailing of the themed maps and determination of the variable values involved in each method. The results can be used as alerts to preventive ways incorporated into the city’s guide plan and risks plan as a criterion for the impediment of anthropic occupation or the evacuation of unstable areas when the rate rainfall exceeds the established limits.