A STUDY ABOUT LAND USE AND LAND COVER CHANGES IN NEGRO RIVER WATERHED, RIO GRANDE DO SUL, BRAZIL, BETWEEN 1977 AND 2016

This paper presents the results of land use and land cover changes mapping in Negro River Watershed, Rio Grande do Sul, Brazil, over a period of 39 years, between 1977 and 2016. For this purpose, we used Landsat satellites series images (1977, 1985, 1996, 2003 and 2016) and Digital Image Processing (PDI) and geographic data analysis using Geographic Information System (GIS) techniques. The Maximum Likelihood method was chose for the supervised classification of satellite images. Based on the results of the mapping, we verified that the predominant LULC classes throughout the study period were: forest area, field and temporary culture. At first, the classes "field" and "temporary culture" began to occupy areas previously occupied by the class "forest area". In a second moment, the class " temporary culture" happened to occupy areas previously occupied by the " field" class. These changes coincided with the significant increase in soybean cultivation in the municipalities covered by the Rio Negro-RS river basin. In 2016, soybeans occupied 75,000ha, corresponding to 75.20% of the entire area occupied by temporary crops in these municipalities.