Proposta metodológica para elaboração de um índice espacial de sustentabilidade ambiental aplicado a bacias hidrográficas
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Data
2016-11-04
Autores
Silva, Darllan Collins da Cunha e [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Índices e indicadores ambientais são importantes mecanismos para a comunicação de informações resumidas sobre o estado em que se encontra uma Bacia Hidrográfica. A escolha da Bacia Hidrográfica como unidade de gestão territorial neste estudo foi baseada na Lei 9.433/97, enquanto que, a utilização de índices e indicadores se deve ao fato de sua comprovada eficiência em processos de gestão. Visto isso, elaborou-se um Índice de Sustentabilidade Ambiental de Bacias Hidrográficas (ISABH) que integrou informações sociais, econômicas e ambientais visando analisar a sustentabilidade dessas unidades de gestão territorial e servir de instrumento de comparação entre as Bacias Hidrográficas. Além disso, avaliou-se a correlação espacial entre as Sub-Bacias Hidrográficas com objetivo de identificar padrões ou agrupamentos que possam facilitar a gestão pública dessas unidades. Dentro das dimensões adotadas, os indicadores e índices foram selecionados considerando-se as bases territoriais definidas pelo recorte dos setores censitários municipais bem como pelo recorte das Sub-Bacias Hidrográficas. Nesse caso, o índice privilegiou as variáveis que pudessem gerar uma superfície de distribuição espacial dos dados ao longo da Bacia Hidrográfica. Para o estudo do ISABH escolheu-se a Bacia Hidrográfica do Rio Una, que está localizada no interior do Estado de São Paulo a aproximadamente 75km da capital do Estado de São Paulo, no município de Ibiúna. A partir dos resultados obtidos, foi possível verificar que os valores mais baixos do ISABH ocorrem ao sul da Bacia Hidrográfica e estão inseridos na zona rural do município de Ibiúna/SP sob influência de atividades agrícolas e péssimas condições de saneamento básico. Ainda, essas áreas apresentam altas taxas de analfabetismo e baixas taxas de renda per capita dos residentes. Além disso, apenas 19,4% da área de estudo apresentaram valores de ISABH iguais ou acima de 0,60, indicando uma qualidade razoável, longe da desejável, isto é, superior a 0,9. Com relação a qualidade da água, verificou-se uma baixa concentração de oxigênio dissolvido nos corpos hídricos, isto é, abaixo do permitido pela legislação, especialmente nas áreas onde a presença das atividades agrícolas é intensa. Em relação à perda de nutrientes (fertilidade), pode-se afirmar que há uma carência de fósforo no solo ao longo da Bacia Hidrográfica devido a perda desse nutriente por erosão hídrica, resultando em um custo elevado para sua reposição na área de estudo. Esse índice demonstrou ser uma importante ferramenta para fornecer subsídios à formulação de políticas públicas e servir de apoio à tomada de decisão por atores públicos e privados.
Environmental index and indicators are important mechanisms for report summarized information about the state of Watershed. The choice of the Watershed as a territorial management unit in this study was based on Law 9,433/97, while the use of index and indicators is because its proven efficiency in management processes. Therefore, was prepared an Environmental Sustainability Index of Watershed (ISABH) that integrated social, economic and environmental information to analyze the sustainability of these territorial management units and serve as a comparison tool between the Watershed. Furthermore, we evaluated the spatial correlation between the Micro-Watersheds to identify patterns or groups that can facilitate public management of these units. Within the adopted dimensions, indicators and index were selected considering the territorial bases defined by the limits of the municipal census tracts as well as the outline of the Micro-Watersheds. In this case, the index favored the variables that could generate a spatial distribution of surface data along the Watershed. To study the ISABH was choose the Una River Watershed, which is located in the State of São Paulo, approximately 75km from the capital of São Paulo, in the city of Ibiúna. From the results, was found that the lowest values of ISABH occur on south of the watershed and are inserted in the rural city of Ibiúna/SP under the influence of agricultural activities and poor sanitation conditions. Still, these areas have high rates of illiteracy and income per capita lower of the residents. Furthermore, only 19.4% of the study area shows of ISABH values equal or above 0.60, indicating a reasonable quality, far from desirable, i.e, greater than 0.9. Regarding water quality, was verified a low concentration of dissolved oxygen in the water bodies, i.e, below those permitted by law, especially in areas where the presence of agricultural activities are intense. About the loss of nutrients (fertility), it can be checked that there is a phosphorus deficiency in the watershed soil due to loss of this nutrient by water erosion, resulting in a high cost for their replacement in the study area. This index proved to be an important tool to provide input to the formulation of public policies and provide support to decision-making by public and private actors.
Environmental index and indicators are important mechanisms for report summarized information about the state of Watershed. The choice of the Watershed as a territorial management unit in this study was based on Law 9,433/97, while the use of index and indicators is because its proven efficiency in management processes. Therefore, was prepared an Environmental Sustainability Index of Watershed (ISABH) that integrated social, economic and environmental information to analyze the sustainability of these territorial management units and serve as a comparison tool between the Watershed. Furthermore, we evaluated the spatial correlation between the Micro-Watersheds to identify patterns or groups that can facilitate public management of these units. Within the adopted dimensions, indicators and index were selected considering the territorial bases defined by the limits of the municipal census tracts as well as the outline of the Micro-Watersheds. In this case, the index favored the variables that could generate a spatial distribution of surface data along the Watershed. To study the ISABH was choose the Una River Watershed, which is located in the State of São Paulo, approximately 75km from the capital of São Paulo, in the city of Ibiúna. From the results, was found that the lowest values of ISABH occur on south of the watershed and are inserted in the rural city of Ibiúna/SP under the influence of agricultural activities and poor sanitation conditions. Still, these areas have high rates of illiteracy and income per capita lower of the residents. Furthermore, only 19.4% of the study area shows of ISABH values equal or above 0.60, indicating a reasonable quality, far from desirable, i.e, greater than 0.9. Regarding water quality, was verified a low concentration of dissolved oxygen in the water bodies, i.e, below those permitted by law, especially in areas where the presence of agricultural activities are intense. About the loss of nutrients (fertility), it can be checked that there is a phosphorus deficiency in the watershed soil due to loss of this nutrient by water erosion, resulting in a high cost for their replacement in the study area. This index proved to be an important tool to provide input to the formulation of public policies and provide support to decision-making by public and private actors.
Descrição
Palavras-chave
Bacias Hidrográficas, Índices, Sustentabilidade, Análise Espacial, Watershed, Index, Sustainability, Spatial Analyst