Identificação e avaliação da pressão antrópica no Reservatório Engenheiro Paulo de Paiva Castro: repercussão sobre as águas superficiais da bacia do rio Juqueri no município de Mairiporã - SP
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Data
2017-04-27
Autores
Pérez Ortega, Diego Javier [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As mudanças no uso do solo provocadas pelas atividades antrópicas têm gerado grandes impactos na Bacia do rio Juqueri no município de Mairiporã no estado de São Paulo. Esses impactos foram identificados mediante informações espaço-temporais da classificação de imagens de satélite sensor LANDSAT 5, 7 e 8 dos anos de 1986, 1992, 2003, 2011 e 2016. A bacia se caracterizou por ter 6 classes (área urbana, agrícola, pastagens, floresta, solo exposto e corpos d´água). Além do mais foram utilizados dois índices para as análises da pressão ambiental da bacia. O Índice de Qualidade da Água (IQA) e o Índice de Transformação Antrópica (ITA), onde segundo a Resolução CONAMA 357/2005 os recursos hídricos foram enquadrados com Regular e segundo o ITA a bacia foi catalogada Regularmente Degrada. Referente à disponibilidade hídrica apresentaram-se os meses de julho, agosto e setembro no período de estiagem com a maior pressão nos recursos hídricos, diminuindo sua disponibilidade nos rios, córregos e no reservatório Paiva Castro. As ferramentas estatísticas utilizadas permitiram identificar correlações entre o pH e a DBO com a área urbana, outra correlação entre os sólidos totais e o nitrogênio com as áreas de solo exposto e entre as coliformes, a temperatura e o IQA. Outras correlações se deram entre a área Urbana e os teores de Pb junto com o Cr. Fazendo da área urbana e solos expostos os classes mais influentes nos teores de metais nos pontos da barragem e captação por apresentar o maior número de correlações. O Cu é o mais móvel dos metais, pois tem a capacidade para interagir quimicamente com os componentes minerais e orgânicos onde se estabeleceu incrementos nos teores dos sedimentos nos últimos 30 anos. Determinou-se que as declividades entre o 3 e 12% são as mais suscetíveis à erosão e as de maiores aportes de sedimentos. Com estes dados conclui-se que o uso do solo tem uma forte influência sobre a qualidade dos recursos hídricos indicando um alto risco de degradação na Bacia, ainda assim, no reservatório Paiva Castro, identificou-se certa eficiência na autodepuração dos recursos hídricos, pois obteve os melhores resultados segundo o IQA.
The changes in the use of the soil caused by the anthropic activities have generated great impacts in the Juqueri river basin in the municipality of Mairiporã in the state of São Paulo. These impacts were identified using information spatial-temporal the classification of satellite sensor images LANDSAT 5, 7 and 8 of the years 1986, 1992, 2003, 2011 and 2016. The basin was characterized by 6 classes (urban, agricultural, pasture, Forest, exposed soil and bodies of water). In addition, two indices were used to analyze the basin environmental pressure. The Water Quality Index (WQI) and the Anthropic Transformation Index (ATI), where according to CONAMA Resolution 357/2005, the water resources were classified as Regular and according to the ATI, the basin was classified as Regularly Degraded. About the water availability presented in the months of July, August and September in the period of drought has the greatest pressure on the water resources, decreasing its availability in the rivers, streams and in the Paiva Castro reservoir. The statistical tools used allowed to identify correlations between the pH and the BOD with the urban area, between total solids and nitrogen with areas of soil exposed and between coliforms, temperature and WQI. And correlations of the urban area and the Pb contents together with Cr. Making of the urban area and exposed soils being the most influent in the contents of metals in the points of the dam and capitation because it presents the highest number of correlations. The Cu is the most mobile of the trace metals, since it has the capacity to interact chemically with the mineral and organic components where it has been established increases in sediment contents in the last 30 years. It was determined that the gradients between 3 and 12% are the most susceptible to erosion and those of highest contributions of sediment. With these data it is concluded that land use has a strong influence on the quality of water resources indicating a high risk of degradation in the Basin, even though, in the Paiva Castro reservoir, a certain efficiency was identified in the self-purification of water resources, Because it obtained the best results according to the WQI.
The changes in the use of the soil caused by the anthropic activities have generated great impacts in the Juqueri river basin in the municipality of Mairiporã in the state of São Paulo. These impacts were identified using information spatial-temporal the classification of satellite sensor images LANDSAT 5, 7 and 8 of the years 1986, 1992, 2003, 2011 and 2016. The basin was characterized by 6 classes (urban, agricultural, pasture, Forest, exposed soil and bodies of water). In addition, two indices were used to analyze the basin environmental pressure. The Water Quality Index (WQI) and the Anthropic Transformation Index (ATI), where according to CONAMA Resolution 357/2005, the water resources were classified as Regular and according to the ATI, the basin was classified as Regularly Degraded. About the water availability presented in the months of July, August and September in the period of drought has the greatest pressure on the water resources, decreasing its availability in the rivers, streams and in the Paiva Castro reservoir. The statistical tools used allowed to identify correlations between the pH and the BOD with the urban area, between total solids and nitrogen with areas of soil exposed and between coliforms, temperature and WQI. And correlations of the urban area and the Pb contents together with Cr. Making of the urban area and exposed soils being the most influent in the contents of metals in the points of the dam and capitation because it presents the highest number of correlations. The Cu is the most mobile of the trace metals, since it has the capacity to interact chemically with the mineral and organic components where it has been established increases in sediment contents in the last 30 years. It was determined that the gradients between 3 and 12% are the most susceptible to erosion and those of highest contributions of sediment. With these data it is concluded that land use has a strong influence on the quality of water resources indicating a high risk of degradation in the Basin, even though, in the Paiva Castro reservoir, a certain efficiency was identified in the self-purification of water resources, Because it obtained the best results according to the WQI.
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Palavras-chave
Qualidade de água, Efeitos antrópicos, Ecossistemas aquáticos, Geoprocessamento