Indicadores morfométricos como suporte para a classificação de voçorocas em sub-bacias hidrográficas no Município de Cacequi, RS = Morphometric indicators as support for the classification of gullies in hydrographic sub-basins in the Cacequi municipality, RS

• Autor(a) principal: Cabral, Tiéle Lopes
• Data de Publicação: 2020
• Outros Autores: Nummer, Andrea Valli, Bateira, Carlos
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/10216/130391
• topic: Geografia; Geography

The morphometric indicators directly extracted from erosive incisions are essential for the classifi cation of diff erent forms of gullies, especially in areas that have an environmental fragility linked to erosive and tectonic processes, such as the case of sub-basins located in the central sector of the municipality of Cacequi, southwest of the state of Rio Grande do Sul, Brazil. In order to classify the gullies regarding their form, statistical analyses were performed to defi ne the morphometric indexes to be used, such as structural lineaments, area measurements, perimeter, length, width, volume, depth and Circulation Index of each incision. For the extraction of these indexes, WorldView-2 satellite images with 0.5m resolution and the Digital Elevation Model of the AlosPalsar platform were used, with a resolution of 0.5 meter, using the Geographic Information Systems for data processing, which made it possible to organize a large database containing all the information. All this process favored the analysis, giving satisfactory support to the understanding of the behavior of erosive features, relief and lithology in the regional context, thus evidencing the main forms of gullies: Linear, Bulbiform, Branched, Mixed Irregular, Rectangular and Irregular Rectangular. The gullies were grouped into three sets due to the similarity of the morphometric data: in the fi rst are the Linear and Bulbiform forms, with smaller values of area, depth and volume; in the second, the Branched and Irregular Mixed forms that have the largest areas, perimeters, altimetric amplitudes and depths. In the third set are the Rectangular and Irregular Rectangular forms with intermediate values of these indexes. Based on morphometric indexes, fi eldwork and gully form, it was possible to suggest a scenario of evolution of the erosion process for the study area. The gullying process supposedly starts by the Linear form, until it reaches the Rectangular form, considered the most advanced stage. The Mixed Irregular form could result from the evolution of a Linear or Bulbiform and evolve into a Rectangular Irregular with increasing Circularity Index. The Rectangul