Dinâmica de distúrbios antropogênicos no semiárido brasileiro: bacia hidrográfica do rio Jaguaribe - Ceará

Abstract

Changes in land use and land cover have generated major changes in the landscape, directly affecting natural resources and biodiversity on a local and global scale. Bearing in mind that the negative effects of changes in land use and land cover can be enhanced in arid and semi-arid areas, the present work aims to analyze the detailed spatiotemporal changes in the dynamic use and land cover of the Jaguaribe River basin (BHRJ), Ceará, for a period of 34 years. Specific objectives include: (i) identifying the dynamics of land use and land cover changes from 1985 to 2018; (ii) detect the main preferences for land use and occupation during this period and (iii) identify which sub-basin was most affected by historical changes in land use and cover. For the development of the research were the images used annually from the Mapbiomas project (project of annual mapping of coverage and use and land cover in Brazil), and the software ArcGIS and R (R Core Team). The proposals for land use/cover were determined by means of cross-tabulation analysis and flow diagram and to evaluate the dynamics of use/land cover, the pixel by pixel concordance analysis was used. In the last three decades, there has been a decrease in the areas of natural vegetation (areas of dense arboreal and herbaceous scrubland) and the expansion of agricultural and livestock areas, showing that the disturbances occur from the largest anthropogenic activities of landscape change in the hydrographic basin of the Jaguaribe River. The sub-basins most affected by historical changes in land use and land cover were the Middle Jaguaribe and the Low Jaguaribe. The characteristics of the landscape in the Middle Jaguaribe sub-basin reveal that this area has been and continues to be quite impacted by anthropic interference, since the pasture class and the caatinga class have had similar areas since 1985. The Low Jaguaribe sub-basin being continuously impacted by the expansion of the annual and perennial culture and the consequent reduction of areas of natural vegetation. Dynamics analyzes reveal that a sub-basin in the Low Jaguaribe has a higher percentage of altered areas, a lower percentage of fashion frequency, a higher number of uses per pixel and a greater number of changes in use.