Diagnóstico ambiental da bacia hidrográfica do Arroio Moreira (RS), a partir da análise da dinâmica de cobertura e uso da terra em consonância com o novo código florestal.

Abstract

This dissertation aims to analyze the application of the current Brazilian forest code, together with the dynamics of hydrographic and land-use changes in the Arroio Moreira Hydrographic Basin (Rio Grande do Sul - Brazil), to proposing an environmental diagnosis that establishes priority areas for protection and recovery in the study area. Initially, a bibliographical review on the subject was performed, scientifically coherent with the concepts of sustainable development and that highlights the complexity of the interpretation at the Brazilian forest law (also recognized as the Brazilian native vegetation protection law) in the environmental regularization of rural properties. Subsequently, the environmental and socioeconomic data of the study area were analyzed geographically, seeking to understand aspects of geology/geomorphology, soils, hydrography, land use capacity, climate and agricultural and livestock production. The cartographic base of this research was elaborated by manual vectorization, with stereoscopy techniques, interpretation of aerial photographs and satellite images. A symbology adapted to the representation of natural and anthropogenic features was used to visualize data referring to the scenarios of the years 1964, 2008 and 2014. The hydrographic mappings allowed observing the conversion of watercourses from native fields into artificial channels linked to irrigated rice fields. The sector in which most changes occurred was in the upper land of the Basin, through the expansion of the paddy fields. Land use mappings indicated major changes in the hydrographic basin by anthropic processes, with the replacement of field areas by pastures and temporary crops, with emphasis on rice fields. This dynamic matches with socioeconomic data, due to older irrigation projects that promoted the expansion of rice crops over native fields and wetlands. Correlating the cartographic bases of land use maps, hydrographic maps and the limits of rural properties (by Rural Environmental Registry - Cadastro Ambiental Rural, in Portuguese), 76 rural properties were identified in the study area, with 15.38 km² of Permanent Preservation Areas, with only 8.97 km² of preserved native vegetation. The remaining area has 6.41 km² with agricultural use and can be considered as a (Rural) Consolidated Area. Results identified more environmentally fragile areas and areas with native vegetation. Therefore, with these data, it is expected to contribute to the understanding of the use of the Brazilian forest code for the purpose of environmental diagnosis, establishing priority areas for environmental protection and recovery.