Changes in the water resources, soil use and spatial dynamics of Caatinga vegetation cover over semiarid region of the Brazilian Northeast

Abstract

The Brazilian semiarid suffers from the reflex of high rainfall variability, with rainfall concentrated over time, with little spatial distribution. In this sense, presenting a highly dynamic vegetation cover, which requires constant monitoring of the changing conditions of different land uses and the utilization of water resources. The objective was to monitor and evaluate the spatial dynamics of vegetation cover of Caatinga and water availability through the vegetation index and the estimation of biophysical parameters of the energy balance, using remote sensing techniques with satellite images for a semiarid region of the Northeast Brazil. The study was developed from the digital processing of three images from the Landsat-8 satellite, with the implementation of the SEBAL algorithm. The analysis of the orbital data allowed the development of thematic maps of land cover and use, of the MNDWI vegetation index and the parameters of the water balance: evaporative fraction and relative humidity of the soil, these evaluated for their spatial variability. The main results showed a reduction of the areas covered by water bodies close to 50% (2156.18 ha), between the years 2013 to 2015. The semiarid region, in this period, also presented an annual growth of the agriculture and livestock sector in at least 3374.07 ha, followed by the reduction of the native forest of Caatinga. The conditions of changes in soil use have altered over time the spatial dynamics of the Caatinga vegetation, evidenced by changes in the response patterns obtained in the biophysical parameters of the energy balance of the Earth's surface.