Grau de preservação da mata ripária com uso de dados do MapBiomas: o caso do Rio Umbuzeiro, Ceará

Abstract

In the Brazilian semi-arid region, the riparian forest is one of the vegetation formations that most suffers from degradation due to improper use. Found close to scarce water sources, riparian zones are highly exploited, especially for agricultural activities. Remote assessment of land use and land cover are of great importance in the study of soil, water and vegetation quality, which allows evaluating the evolution of a region with more assertiveness. Remote sensing makes it possible to assess the degree of preservation of riparian vegetation close to water courses as well as its evolution over time, in addition to the degree of conservation of the water resources involved. The MapBiomas project has an online platform where it is possible to find the evolution of all Brazilian biomes between 1985 and 2020, with a detailed classification of 27 land use classes. Given this scenario, the objective of this study was to evaluate the degree of preservation of the riparian forest of the Umbuzeiro River, the main river of the Benguê Basin, located in the municipality of Aiuaba, Ceará, using orbital remote sensing data. The Umbuzeiro River was analyzed along its entire length with different areas called riparian zones, being related from the widths of 30, 60, 90, 120, 150, 180, 210, 240, 270 and 300 meters between the years of 1985, 1990, 1995, 2000, 2005, 2010, 2015 and 2020. Of the 27 land use and land cover classes classified by MapBiomas, nine were found in the riparian zone of the Umbuzeiro River, namely: grassland formation, forest formation, savanna formation, urbanized, unvegetated areas, agriculture and pasture mosaic, pasture, water resources and temporary crops. It was possible to conclude that the classes that suffered losses between 1985 and 2020 were those of savanna formation, where it presented the highest loss among all classes, with 28.28% of its total area at all distances and non-vegetated areas, losing 0.41% of its total area. Among the areas that had an increase in their area, we could highlight the pasture classes, which gained 14.79% of the total area and the agriculture and pasture mosaic class, which gained 4.69%. The grassland formation class showed an increase of 3.19%, while in the forest formation class, this growth was 1.26%. The urbanized area class expanded by 0.73%. Finally, it was also possible to observe that the class of water resources had an increase in its area, with 3.07% in all analyzed distances, this is due to the creation of the Benguê weir that provided the flooding of a stretch of the Umbuzeiro River due to the concentration of water in the region. Despite filling large areas of the riparian zone of the Umbuzeiro River, it was possible to notice that the vegetation continues to suffer degradation over the years.