Análise do uso do solo na microbacia do ribeirão bandeirinha para fins de restauração de áreas de preservação permanente

Abstract

The riparian forests present in the Areas of Permanent Preservation serve as ecological corridors for flora and fauna, help in the infiltration of water into the soil, prevent siltation and promote the maintenance of quality and regularization of the water available in a watershed. Despite their environmental and economic importance, riparian forests are under constant anthropic pressure, mainly due to the expansion of agricultural activities. To obtain information about the increase or decrease of riparian forest areas over time and thus direct restoration actions in these areas – either through natural processes or active restoration methods – the use of remote sensing to map the land use and land cover of a particular watershed presents itself as a useful tool for several aspects. Thus, this work aimed to map and analyze the changes in the land use and land cover in the watershed of Bandeirinha River, located in the municipality of Antônio Carlos – Minas Gerais, which is used for public supply of the municipality. The QGis software was used to obtain the delimitation of the studied watershed. In turn, the Google Earth Engine platform was used for the supervised classification with Random Forest technique of the Sentinel-2 satellite images in the years 2017, 2019, and 2021 and, the data validation was obtained using confusion matrix and Kappa index. For temporal analysis of the permanent preservation areas, a 50m buffer was applied around the hydrograph. Six land use and land cover classes were obtained and a Kappa index of 0.81 was considered satisfactory. In general, the Agriculture class presented the highest percentage of land cover during the studied period. However, there was a decrease in its percentage of 24% over the years. Next, the Native Forest class occupied the second largest coverage, also showing a decrease over time (10%). The Pasture and Bare Land classes had an increase of 36% and 231%, respectively, during the same period. When analyzing the coverage in the area delimited by the buffer, the Native Forest class showed a small variation. As observed throughout the watershed, the Bare Land class presented a significant increase in its percentage (170%), generating an alert for this watershed that is used for water supply, since in the Areas of Permanent Preservation, the Bare Land can carry sediment causing siltation of the watercourse and the worsening of its quality. Therefore, the study area should receive greater attention to the restoration of riparian forests to guarantee the availability of water in the watershed over the years.