Análise das modificações da cobertura vegetal da planície fluvial do alto rio paraná no período entre 1976 e 2007

Abstract

The removal of vegetation from the Paraná river floodplain has been increasing since the 1950s the until present time, but no study has been made about its spatial distribution. The purpose of this paper is to map and analyze the temporal evolution of vegetation distribution over the Parana river floodplain between 1976 and 2007. Orbital images from 1976 (LANDSAT MSS-1), 1987 (LANDSAT TM-5), 2000 (LANDSAT ETM+7) and 2007 (CBERS-2 CCD) were utilized to compare the evolution of the vegetation distribution over that time period. The images were georeferenced using SPRING 4.3.3 software and classified by the Bhattacharya algorithm; the maps were produced using the Global Mapper 7.4 software. Three different classes of vegetation, water bodies and exposed soil areas were distinguished for each studied year. The comparison of the generated vegetation maps showed a significant enlargement of the water bodies and a position change of the humid vegetation areas between 1976 and 1987, among other small modifications in the referred classes between 1987 and 2007. This indicates that the major river floods modified the morphology of the floodplain, and that the continuous enlargement of the exposed soil areas, along with the reduction of the vegetation areas, showed that anthropic action over the floodplain has increased over the years.