Análise da suscetibilidade à inundação na Bacia Hidrográfica do Ribeirão do Enxofre por meio de ferramentas de geoprocessamento
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2022-06-22
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Universidade Estadual Paulista (Unesp)
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Os desastres naturais ocasionados por fenômenos de inundação e alagamentos são os mais comuns no território brasileiro, causando impactos sociais e ambientais. Os mapeamentos das áreas suscetíveis à inundação podem auxiliar no planejamento urbano, pois permitem orientar a expansão urbana, frente à natural predisposição dos terrenos desenvolverem processos de inundação. O uso do geoprocessamento tem sido cada vez mais utilizado na gestão ambiental, por se tratar de uma ferramenta que possibilita agilizar levantamentos de dados, mapeamentos e análises ambientais. Nesse sentindo, o presente trabalho tem como objetivo elaborar um mapeamento da suscetibilidade à inundação na Bacia Hidrográfico do Ribeirão do Enxofre (BHRE), utilizando ferramentas de geoprocessamento. O município de Piracicaba apresenta um histórico de eventos de inundações em diversos pontos desde 1970. Foram integrados quatro mapas temáticos: a) altitude; b) padrões de relevo; c) altura acima da drenagem mais próxima (Height Above the Nearest Drainage – HAND, em inglês) e; d) caracterização morfométrica por sub-bacia, utilizando como referência básica o documento “Nota Técnica para Elaboração de Modelagens de Inundação do CPRM”. Para a elaboração das bases cartográficas dos mapas, foram vetorizadas informações altimétricas e planimétricas de cartas topográficas do Instituto Geográfico e Cartográfico do Estado de São Paulo - IGC. Os procedimentos foram realizados utilizando o software ArcGIS 10.5. O método adotado para a elaboração do mapeamento da suscetibilidade à inundação da BHRE foi a Análise Hierárquica de Processos (AHP). As altitudes BHRE variaram entre 467,25m e 596,76m. Os relevos encontrados na área de estudo foram: planícies de inundação, terraços fluviais, colinas e morrotes. De acordo com a cota HAND, 17,85% da área BHRE, foi classificada com alta suscetibilidade à inundação. As variáveis morfométricas obtidas indicaram que as sub-bacias possuem características físicas que influenciam na propensão dos processos de inundação. Com relação ao método AHP, a ordem de importância dos critérios foi: HAND, padrões de relevo, altimetria e morfometria, respectivamente. As áreas com maior suscetibilidade corresponderam 18,83% da área BHRE, coincidindo com as áreas de baixas altitudes, em relevos planos próximas ao Ribeirão do Enxofre e seus afluentes. As áreas de média suscetibilidade corresponderam 73,07% da área da bacia e essas localidades estão próximas aos cursos d’água, em médias altitudes e em relevos suave-ondulado e ondulado. Já as áreas de baixa suscetibilidade corresponderam 7,88% e representam as regiões de altitudes mais elevadas. Os fatores naturais da BH relacionados à geomorfologia, pedologia, altimetria, proximidade da rede de drenagem e a forma, demonstraram ser elementos indicadores da predisposição dos terrenos a ocorrência de inundação.
Natural disasters caused by flooding phenomena are the most common in Brazilian territory, causing social and environmental impacts. The mapping of areas susceptible to flooding can help in urban planning, as they allow orienting urban expansion, given the natural predisposition of land to develop flooding processes. The use of geoprocessing has been increasingly used in environmental management, as it is a tool that makes it possible to speed up data collection, mapping and environmental analysis. In this sense, the present work aims to develop a mapping of the susceptibility to flooding in the Ribeirão do Enxofre Hydrographic Basin (BHRE), using geoprocessing tools. The municipality of Piracicaba has a history of flooding events at different points since 1970. Four thematic maps were integrated: a) altitude; b) relief patterns; c) height above the nearest drainage (Height Above the Nearest Drainage – HAND) and; d) morphometric characterization by sub-basin, using the document “Technical Note for Elaboration of CPRM Flood Modeling” as a basic reference. For the elaboration of the cartographic bases of the maps, altimetric and planimetric information of topographical maps of the Geographical and Cartographic Institute of the State of São Paulo - IGC were vectorized. The procedures were performed using ArcGIS 10.5 software. The method adopted for the elaboration of the mapping of the susceptibility to flooding of the BHRE was the Hierarchical Analysis of Processes (AHP). The BHRE altitudes varied between 467.25m and 596.76m. The reliefs found in the study area were: floodplains, river terraces, hills and hills. According to the HAND quota, 17.85% of the BHRE area was classified as highly susceptible to flooding. The morphometric variables obtained indicated that the sub-basins have physical characteristics that influence the propensity of flooding processes. Regarding the AHP method, the order of importance of the criteria was: HAND, relief patterns, altimetry and morphometry, respectively. The areas with the highest susceptibility corresponded to 18.83% of the BHRE area, coinciding with areas of low altitudes, in flat reliefs close to Ribeirão do Enxofre and its tributaries. The areas of medium susceptibility corresponded to 73.07% of the basin area and these locations are close to water courses at medium altitudes, in smooth-undulating and undulating reliefs. The areas of low susceptibility corresponded to 7.88% and represent the regions of higher altitudes. The natural factors of BH related to geomorphology, pedology, altimetry, proximity to the drainage network and shape, proved to be indicative elements of the predisposition of the land to the occurrence of flooding.Keywords: Natural disasters; Geotechnical charts; AHP; Urban planning.
Natural disasters caused by flooding phenomena are the most common in Brazilian territory, causing social and environmental impacts. The mapping of areas susceptible to flooding can help in urban planning, as they allow orienting urban expansion, given the natural predisposition of land to develop flooding processes. The use of geoprocessing has been increasingly used in environmental management, as it is a tool that makes it possible to speed up data collection, mapping and environmental analysis. In this sense, the present work aims to develop a mapping of the susceptibility to flooding in the Ribeirão do Enxofre Hydrographic Basin (BHRE), using geoprocessing tools. The municipality of Piracicaba has a history of flooding events at different points since 1970. Four thematic maps were integrated: a) altitude; b) relief patterns; c) height above the nearest drainage (Height Above the Nearest Drainage – HAND) and; d) morphometric characterization by sub-basin, using the document “Technical Note for Elaboration of CPRM Flood Modeling” as a basic reference. For the elaboration of the cartographic bases of the maps, altimetric and planimetric information of topographical maps of the Geographical and Cartographic Institute of the State of São Paulo - IGC were vectorized. The procedures were performed using ArcGIS 10.5 software. The method adopted for the elaboration of the mapping of the susceptibility to flooding of the BHRE was the Hierarchical Analysis of Processes (AHP). The BHRE altitudes varied between 467.25m and 596.76m. The reliefs found in the study area were: floodplains, river terraces, hills and hills. According to the HAND quota, 17.85% of the BHRE area was classified as highly susceptible to flooding. The morphometric variables obtained indicated that the sub-basins have physical characteristics that influence the propensity of flooding processes. Regarding the AHP method, the order of importance of the criteria was: HAND, relief patterns, altimetry and morphometry, respectively. The areas with the highest susceptibility corresponded to 18.83% of the BHRE area, coinciding with areas of low altitudes, in flat reliefs close to Ribeirão do Enxofre and its tributaries. The areas of medium susceptibility corresponded to 73.07% of the basin area and these locations are close to water courses at medium altitudes, in smooth-undulating and undulating reliefs. The areas of low susceptibility corresponded to 7.88% and represent the regions of higher altitudes. The natural factors of BH related to geomorphology, pedology, altimetry, proximity to the drainage network and shape, proved to be indicative elements of the predisposition of the land to the occurrence of flooding.Keywords: Natural disasters; Geotechnical charts; AHP; Urban planning.
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Desastres naturais, Cartas geotécnicas, AHP, Planejamento urbano, Natural disasters, Geotechnical maps, Urban planning