Aplicação da abordagem geotecnogênica no entendimento das transformações da paisagem na bacia hidrográfica do rio Mandaguari, Oeste Paulista, Brasil
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Data
2020-04-03
Autores
Dias, Marcel Bordin Galvão
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Universidade Estadual Paulista (Unesp)
Resumo
Os depósitos tecnogênicos originam-se a partir da ação geológica humana, capaz de alterar as características dos processos superficiais e, com isso, as formas de relevo e os materiais constituintes. O presente trabalho propôs-se a investigar as transformações na paisagem ocorridas na bacia hidrográfica do rio Mandaguari, situada no oeste paulista, utilizando como foco analítico as deposições tecnogênicas ocorrentes nos fundos de vale. Para tanto, elegeu-se como ferramenta analítica a abordagem geotecnogênica, a qual pressupõe que os processos e materiais geológicos estão sujeitos aos condicionantes tecnogênicos, representativos da ação geológica humana transformadora da superfície terrestre. A referida abordagem considera a utilização de procedimentos típicos das Geociências para a análise do meio físico, acrescidos do resgate histórico do uso e ocupação da terra, necessário para a compreensão da dinâmica geotecnogênica. Os procedimentos adotados neste estudo envolveram atividades de gabinete, como revisão da literatura e elaboração de mapeamentos; de campo, para identificação das deposições tecnogênicas e coleta de amostras; e de laboratório, como a realização de análise granulométrica e de datação das amostras coletadas. A partir dos procedimentos executados, foi possível caracterizar as deposições tecnogênicas amostradas, de textura majoritariamente arenosa, estratificação plano-paralela, com ou sem a presença de artefatos, constituídas por materiais oriundos dos processos erosivos instalados nas vertentes, responsáveis pela produção dos sedimentos que entulharam os fundos de vale, resultando na formação de depósitos tecnogênicos, posteriormente retrabalhados pela atividade fluvial, o que evidencia o caráter descontínuo dos processos erosivos, condicionados pelos diferentes usos da terra implementados na área ao longo tempo. Assim, a abordagem geotecnogênica e os procedimentos adotados mostraram-se adequados aos propósitos do trabalho, ao considerar as práticas de uso da terra e seus desdobramentos sobre a dinâmica dos processos superficiais, fornecendo elementos para o entendimento da dinâmica e evolução da paisagem.
Technogenic deposits originate from human geological action, capable of altering the characteristics of surface processes and, with this, the forms of relief and constituent materials. The current work aimed to investigate the transformations in the landscape that occurred in the hydrographic basin of the Mandaguari river, located in the west of São Paulo state, using as an analytical focus the technogenic depositions occurring in valley bottoms. To this end, the geotechnogenic approach was chosen as an analytical tool, which assumes that geological processes and materials are subject to technogenic conditions, representative of the human geological action that transforms the earth's surface. This approach considers the use of typical Geoscience procedures for the analysis of the physical environment, in addition to the historic use and occupation of the land, necessary to understand the geotechnogenic dynamics. The procedures adopted in the study involved office activities, such as literature review and mapping; field activities, to identify technogenic depositions and sample collection; and laboratory activities, such as carrying out granulometric analysis and dating the collected samples. From the procedures performed, it was possible to characterize the sampled technogenic depositions, mostly sandy in texture, plane-parallel stratification, with or without the presence of artifacts, consisting of materials from the erosive processes on the slopes, responsible for the production of the sediments deposited on valley bottoms, resulting in the formation of technogenic deposits, later reworked by river activity, which demonstrates the discontinuous nature of erosion processes, conditioned by the different land uses implemented in the area over time. Thus, the geotechnogenic approach and procedures adopted proved to be adequate to the purposes of the work, when considering land use practices and their consequences on the dynamics of surface processes, providing elements for understanding the dynamics and evolution of the landscape.
Technogenic deposits originate from human geological action, capable of altering the characteristics of surface processes and, with this, the forms of relief and constituent materials. The current work aimed to investigate the transformations in the landscape that occurred in the hydrographic basin of the Mandaguari river, located in the west of São Paulo state, using as an analytical focus the technogenic depositions occurring in valley bottoms. To this end, the geotechnogenic approach was chosen as an analytical tool, which assumes that geological processes and materials are subject to technogenic conditions, representative of the human geological action that transforms the earth's surface. This approach considers the use of typical Geoscience procedures for the analysis of the physical environment, in addition to the historic use and occupation of the land, necessary to understand the geotechnogenic dynamics. The procedures adopted in the study involved office activities, such as literature review and mapping; field activities, to identify technogenic depositions and sample collection; and laboratory activities, such as carrying out granulometric analysis and dating the collected samples. From the procedures performed, it was possible to characterize the sampled technogenic depositions, mostly sandy in texture, plane-parallel stratification, with or without the presence of artifacts, consisting of materials from the erosive processes on the slopes, responsible for the production of the sediments deposited on valley bottoms, resulting in the formation of technogenic deposits, later reworked by river activity, which demonstrates the discontinuous nature of erosion processes, conditioned by the different land uses implemented in the area over time. Thus, the geotechnogenic approach and procedures adopted proved to be adequate to the purposes of the work, when considering land use practices and their consequences on the dynamics of surface processes, providing elements for understanding the dynamics and evolution of the landscape.
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Palavras-chave
Paisagem, Bacia hidrográfica, Rio Mandaguari, Abordagem geotecnogênica, Landscape, Hydrographic basin, Mandaguari river, Geotechnogenic approach