Standards for shallow landslide identification in Brazil: Spatial trends and inventory mapping

Author(s)

Dias, Helen Cristina ; Grohmann, Carlos Henrique

• Document type: Journal article
• Source: Journal of South American Earth Sciences; v. 135, p. 10-pg., 2024-01-24.

Abstract

Mapping shallow landslide inventories represents the initial stage in conducting susceptibility, vulnerability, and risk analyses. The identification of areas with a history of landslides, both past and current events, enables the detection of spatio-temporal patterns and facilitates the evaluation of morphological and geological factors. Shallow landslides are frequent in Brazil, especially along the Brazilian south and southeastern coast. Despite their high frequency, the recognition and mapping of these landslides are inadequately developed due to the absence of established mapping guidelines. This resulted of limited investments by Brazilian authorities in initiatives aimed at preventing and mitigating mass movements. Thus, the aim of this study is to establish criteria for the recognition and mapping of shallow landslides in Brazil and to evaluate their applicability in susceptibility analysis. The study area is located in Itaoca and Apiaimunicipalities, Sao Paulo state, southeastern Brazil. Criteria for shallow landslide recognition were created based on the absence of vegetation, shape and size, drainage network distance, slope position, planar rupture surface, and altimetric variation. An extensive landslide interpretation was carried out using a set of free access Google Earth Pro images. Susceptibility maps were developed through a bivariate statistical approach, specifically the Informative Value method. The outcomes demonstrated that incorporating the deposition area in susceptibility studies for shallow landslides led to modifications in the final mapping, a slight reduction in validation rates, and, notably, an impact on the influence of the thematic variable curvature. Therefore, it is clear that the criteria used for landslide inventory maps have a significant effect on the accuracy of susceptibility maps and should be a critical consideration in studies related to this subject. (AU)

• FAPESP's process: 18/08402-4 - Magnitude potential and susceptibility of watersheds to the occurrence of debris flow: evaluation of proposal of national index
• Grantee: Vivian Cristina Dias
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 22/01534-8 - Creation and assessment of shallow landslides inventories based on the Object-Based Image Analysis (OBIA) method
• Grantee: Helen Cristina Dias
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 19/17261-8 - Analysis of manual and semi-automatic shallow landslides inventories and its suitability in predictive models
• Grantee: Helen Cristina Dias
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/26568-0 - High-resolution remote sensing, deep learning and geomorphometry in analyses of mass movements and geological risk
• Grantee: Carlos Henrique Grohmann de Carvalho
• Support Opportunities: Regular Research Grants