EVALUATION OF SUSCEPTIBILITY TO SHALLOW LANDSLIDES IN MAQUINÉ/RS AND THE FIELD DATA INFLUENCE ON THE QUALITY OF HAZARD MAPPING

Abstract

Identifying susceptible regions to landslides and mapping hazardous areas are essential tools in managing the risk and disasters associated with these natural phenomena. One of the most used tools for mapping these areas is numerical modeling. Thus, the objective of the present study was to characterize the geotechnical units (UGs) in the Maquiné/RS river basin, perform hazard mapping and evaluate the influence of geotechnical data collected in the field on the quality of the mapping. The SHALSTAB model was used, considering the characterization of the basin's UGs with data obtained through in situ and laboratory soil analyses. Thus, three scenarios were simulated: scenario-1: default (with the values ​​recommended by the original SHALSTAB); scenario-2: average (with a single value for each parameter, this being the average of the values ​​obtained in the field); and scenario-3: discretized (with spatialized values ​​for each UG). Through the efficiency indexes used (Hit Index and Error Index), the results obtained showed that scenario-3 presented the best performance, demonstrating the importance of spatialization with the GUs and the use of local data for a greater quality of the mappings performed with SHALSTAB.