Metodologia de avaliação de degradação ambiental utilizando técnicas de geoprocessamento e sensoriamento remoto na Bacia Hidrográfica do Rio Cotia - SP
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Data
2020-11-27
Autores
Toniolo, Bruno Pereira
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Universidade Estadual Paulista (Unesp)
Resumo
As cargas pontuais e difusas de poluição contribuem para a degradação ambiental, especialmente na qualidade dos recursos hídricos. Diante disso, o objetivo desta pesquisa foi avaliar os efeitos das atividades antrópicas na Bacia Hidrográfica do Rio Cotia (SP) sobre a qualidade das águas superficiais e a poluição de origem difusa com os diferentes usos e ocupação da terra, a partir de uma análise multitemporal com o auxílio de geotecnologias. A partir da delimitação de áreas de contribuição de cinco postos de monitoramento, foram determinados os parâmetros morfométricos, o mapeamento do uso da terra e a determinação dos seguintes indicadores ambientais: Índice de Qualidade da Água (IQA), Índice de Transformação Antrópica (ITA), Potential Non-Point Pollution Index (PNPI) e o Modelo de Correlação entre o Uso do Solo e Qualidade da Água (MQUAL). A análise morfométrica mostrou que a bacia tem formato alongado, é pouco sujeita a inundações e de ordem hídrica igual a seis. A qualidade da água no Baixo Cotia oscila entre Regular e Ruim e o Alto Cotia possui uma qualidade Ótima devido à conservação de sua vegetação nativa. Foi constatada que a precipitação pode influenciar nas alterações de alguns parâmetros de qualidade como Temperatura, Nitrogênio Total e Fósforo Total. A expansão urbana foi crescente entre 2002 a 2019, suprimindo a cobertura vegetal e colocando em risco os recursos naturais. O ITA classificou a bacia como de degradação moderada, sendo o Baixo Cotia classificado como fortemente degradado e o Alto Cotia como fracamente degradado. O PNPI médio da bacia é categorizado como de baixo potencial, apresentando manchas isoladas de alto potencial, inclusive nas margens do Rio Cotia. O MQUAL indicou que o aporte diário de poluentes na bacia é notável, com cerca de 10 kg de Fósforo Total, 200 kg de Nitrogênio Total e 8 toneladas de sólidos em suspensão, de forma que as classes mais poluidoras são a área urbana e indústria. A correlação linear entre o ITA e o IQA confirmou que as classes antropizadas do uso da terra são inversamente proporcionais à qualidade da água e que as áreas naturais influenciam de forma benéfica ao IQA.
The punctual and diffuse pollution loads contribute to environmental degradation, especially in the quality of water resources. Therefore, the objective of this research was to evaluate the effects of anthropic activities in the Cotia River Watershed (SP) regarding the water quality and diffuse pollution with different uses and land occupation, based on a multitemporal analysis using geotechnologies. From the delimitation of the contribution areas of five monitoring posts, the morphometric parameters, the mapping of land use and the following environmental indicators were determined: Water Quality Index (IQA), Anthropic Transformation Index (ITA), Potential Non-Point Pollution Index (PNPI) and the Correlation Model Between Land Use and Water Quality (MQUAL). The morphometric analysis showed that the basin has an elongated shape, is little predisposed to flooding and has a hydric order equal to six. The water quality in Low Cotia oscillates between regular and poor and High Cotia has an excellent quality due to the conservation of its native vegetation. It was found that precipitation can influence changes in some quality parameters such as Temperature, Total Nitrogen and Total Phosphorus. The urban expansion increased between 2002 and 2019, suppressing vegetation cover and putting natural resources at risk. The ITA classified the basin as moderately degraded, Baixo Cotia classified as highly degraded and Alto Cotia as weakly degraded. The watershed's average PNPI is categorized as low potential, with isolated high potential patches, including on the banks of the Cotia River. The MQUAL indicated that the daily supply of pollutants in the watershed is remarkable, with about 10 kg of Total Phosphorus, 200 kg of Total Nitrogen and 8 tons of suspended solids, so that the most polluting classes are the urban area and industry. The linear correlation between the ITA and the IQA confirmed that the anthropized classes of land use are inversely proportional to the quality of the water and that the natural areas have a beneficial influence on the IQA.
The punctual and diffuse pollution loads contribute to environmental degradation, especially in the quality of water resources. Therefore, the objective of this research was to evaluate the effects of anthropic activities in the Cotia River Watershed (SP) regarding the water quality and diffuse pollution with different uses and land occupation, based on a multitemporal analysis using geotechnologies. From the delimitation of the contribution areas of five monitoring posts, the morphometric parameters, the mapping of land use and the following environmental indicators were determined: Water Quality Index (IQA), Anthropic Transformation Index (ITA), Potential Non-Point Pollution Index (PNPI) and the Correlation Model Between Land Use and Water Quality (MQUAL). The morphometric analysis showed that the basin has an elongated shape, is little predisposed to flooding and has a hydric order equal to six. The water quality in Low Cotia oscillates between regular and poor and High Cotia has an excellent quality due to the conservation of its native vegetation. It was found that precipitation can influence changes in some quality parameters such as Temperature, Total Nitrogen and Total Phosphorus. The urban expansion increased between 2002 and 2019, suppressing vegetation cover and putting natural resources at risk. The ITA classified the basin as moderately degraded, Baixo Cotia classified as highly degraded and Alto Cotia as weakly degraded. The watershed's average PNPI is categorized as low potential, with isolated high potential patches, including on the banks of the Cotia River. The MQUAL indicated that the daily supply of pollutants in the watershed is remarkable, with about 10 kg of Total Phosphorus, 200 kg of Total Nitrogen and 8 tons of suspended solids, so that the most polluting classes are the urban area and industry. The linear correlation between the ITA and the IQA confirmed that the anthropized classes of land use are inversely proportional to the quality of the water and that the natural areas have a beneficial influence on the IQA.
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Qualidade da Água, Morfometria, Poluição Difusa, Indicadores Ambientais, Geotecnologias, Water Quality, Morphometry, Diffuse Pollution, Environmental Indicators, Geotechnology