Geological-geotechnical risk mapping of gravitational mass movements in an urban area in Colombo, Brazil

This work presents a geological-geotechnical risk map of gravitational mass movements and a susceptibility map to shallow translational slides to Vila Nova community, located in the municipality of Colombo, Brazil. The first map was created through a qualitative mapping methodology and the second one was elaborated using a deterministic method of slope stability. An aerial photogrammetric survey with UAV technology was performed, as well as field reconnaissance, laboratory testing, and geoprocessing techniques. Seven slope failures were identified as well as a range of other evidences of instability associated with the predisposition of the terrain to erosive and gravitational movements linked to human intervention without urban planning and engineering techniques. Moreover, the qualitative and quantitative analyses pointed out that 13% to 9% of the study area, respectively, are in a very high-risk condition for landslides. Thus, the resulting cartographic products are presented as an important technical contribution for landslide risk management as well as land use planning for reducing the geotechnical problems faced on site.