Susceptibility analysis to occurrence inundations by using weighted average and geoprocessing at Dona Francisca – RS

Abstract

Problems directly connected to vegetal cover deforestation, biodiversity decrease, erosion, inundation cause numerous physical, chemical and biological alterations at a certain zone. Therefore, the current study has aimed to identify and characterize the susceptible areas to occur inundations in the city of Dona Francisca – Rio Grande do Sul, through environmental analysis and geoprocessing techniques. For the usage mapping and soil coverage, it was used the Landsat 8 satellite images, OLI sensor, processed in SPRING software version 5.2.7. Related to the variables, geology, geomorphology, soil typology, slope and hydrography, it was utilized the QGIS software version 2.14. For the environmental analysis of susceptible areas to inundation it was utilized the Vista SAGA software. In the Vista SAGA software, it was assigned the weights (100%) and the 0 to 10 grades, that represent very low susceptibility and very high susceptibility respectively, to the different classifications of thematic maps. Posteriorly, the crossing of the thematic maps was performed, by using the weighted average algorithm. The presented results demonstrate that the very high and high susceptibility areas to occur inundations are localized in the west and south regions of the city. About the medium, low and very low susceptibility areas, these have had the biggest representativeness at the study’s area, being located at central, east and north regions. The use of geotechnology allowed the environmental evaluation of the obtained data by different thematic maps, what has enabled integrated view about these aspects of great relevancy to the analysis and mapping of susceptible areas to inundation.