Predicting favourable areas for landsliding through GIS modelling in Aparados da Serra (Brazil)

Abstract

This paper presents the results of GIS modelling for predicting areas where natural landslides can occur in the Aparados da Serra region (Southern Brazil). The scarp is mainly developed upon basalts and dacites (Serra Geral Fm.) and sandstones (Botucatu Fm.) of the Paraná Basin. The 1000 m high scarp has been geomorphologically evolving since the break-up of the Gondwana Supercontinent and the opening of the South Atlantic Ocean. Geologic, geomorphologic and geotechnical mapping were conducted in order to acquire field data and to define a conceptual geomorphologic-geotechnical model for GIS data modelling. These mappings were aided with ASTER image processing and aerial photograph analysis. ASTER images do permit a high resolution and accurate DEM. The prediction of areas able to develop natural landslides along the scarp was based upon Factor of Safety (FS) algorithms. The GIS modelling results for Aparados da Serra region were grouped into four categories. The areas with the lowermost FS number were defined as highly susceptible to developing natural landslides. Field investigations upon some existing landslide structures in the region do confirm such predictions. However, large scale FS determination through GIS modelling in order to predict susceptible areas for landslides must be interpreted in a relative manner. FS modelling can, then, be applied to landslide susceptibility mapping in areas of poor historical records, since supported by adequate geological and geotechnical investigations.

Landslide Susceptibility Mapping in Brazil: A Review

“…Saboya et al [39] considered only expert opinions to validate the susceptibility mapping, such as those provided by geotechnical engineers and geologists. Publications that did not mention any landslide inventories in their analysis carried out landslide susceptibility validations based on expert assessments [39] or using the risk potential index [31]; four publications did not mention any method of validation [12,33,37,47].…”

“…Out of the 33 studies analyzed, 19 of them were in the southeast region, in the states of São Paulo (10) [15,[25][26][27][28][29][30][31][32][33], Rio de Janeiro (7) [12,[34][35][36][37][38][39], Minas Gerais (2) [16,40], and Espírito Santo (1) [41]. The remaining 14 were in the south region, in Rio Grande do Sul (8) [14,35,[42][43][44][45][46][47], Santa Catarina (4) [13,[48][49][50], and Paraná (2) [51,52] (Figure 3). Only the article by Bragagnolo et al [35] had two study areas, one located in Rio Grande do Sul and the other in Rio de Janeiro state.…”

“…The number of publications related to landslide susceptibility mapping in Brazil has increased significantly since 2015 (Figure 5). The first two publications were from 2006 [39,47]. Between 2015 and April 2021, 27 articles were published, comprising about 82% of the database.…”

“…In the WoS database, there are two types of publication: articles (26) and proceedings papers (7). The proceedings papers were published in English and were from four different conferences: the International Symposium on Landslides (4) [13,33,50,51]; the Lusophone Conference on Sciences and Technologies of Geographic Information (1) [52], the International IAEG Congress (1); and theInternational Conference on Evolution, Monitoring, Simulation, Management and Remediation of the Geological Environment and Landscape (1) [47]. The articles were published in 15 different geosciences journals (Figure 5).…”