Risk zoning for flooding and bank erosion: a case study in the community of “Beco do Guarani”, city of Santa Maria, RS

Abstract

The study analyzes and develops the mapping of areas at risk of fluvial processes defined as hydrological flooding/sudden flooding and erosion and undermining of the riverbank in an urban community known as “Beco do Guarani.” The community is in the city of Santa Maria, between the Salgado Filho and Carolina neighborhoods, in the Cadena stream, where the areas of greatest social vulnerability of the neighborhoods occur. The risk analysis and assessment are based on fieldwork with the support of civil defense and the population living in the area. The mapping of the area is conducted using an orthomosaic of aerial photographs obtained with a Mavic Air 2 drone. The flight was conducted at a height of 150 meters with overlaps of 70% on the side and 75% on the front, using the dronelink application to automate the coverage flight. The margin erosion and flooding/ sudden flooding processes affect 47 homes, of which 25 are only margin erosion, 19 are only hydrological and three homes can be affected by both processes.