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Inventário hidrogeológico e dos potenciais focos de contaminação nas bacias hidrográficas da Asprela e Massarelos: implicações no ciclo hidrológico urbano
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Advisor(s)
Abstract(s)
O desenvolvimento incessante em áreas urbanas ameaça a qualidade e quantidade das águas
subterrâneas. O Porto é uma cidade densamente urbanizada, dominada por granitos, os quais constituem
um meio fraturado anisotrópico e heterogéneo. O principal objetivo desta dissertação foi realçar a
importância da cartografia hidrogeológica, bem como a relevância de realizar inventários hidrogeológicos
e de potenciais focos de contaminação para compreender a vulnerabilidade dos sistemas aquíferos na
cidade do Porto. Para tal, foram selecionadas as bacias hidrográficas da Asprela e de Massarelos. Assim,
foram levados a cabo dois inventários, um hidrogeológico e outro das potenciais atividades de
contaminação. O estudo foi apoiado pelos Sistemas de Informação Geográfica (SIG), os quais foram
fundamentais para um melhor conhecimento e integração nas áreas de estudo. Previamente à
implementação dos inventários foi feita uma caracterização das duas bacias, em termos geográficos,
hidroclimatológicos, de ocupação do solo, geomorfológicos e hidrogeológicos. As duas bacias
desenvolvem‐se, principalmente, na unidade hidrogeológica do granito de grão médio a fino, por vezes
com saprólito. O inventário hidrogeológico contemplou principalmente fontanários e nascentes, tendo
incluído, respetivamente, 8 e 21 pontos de água nas bacias da Asprela e de Massarelos. As águas
subterrâneas são límpidas, sem turvação ou cheiro, ácidas, com mineralizações baixas a médias,
temperaturas baixas e caudais muito pequenos. Quanto aos potenciais focos de contaminação, na bacia
da Asprela foram reconhecidos 61, enquanto que na bacia de Massarelos foram identificados 78. A
maioria destas atividades é pontual correspondendo, nomeadamente, a estabelecimentos de ensino e
estações de serviço/oficinas de automóveis. Contudo, os focos lineares apresentam uma difusão
significativa nas duas bacias hidrográficas. Apesar de a vulnerabilidade intrínseca à contaminação das
águas subterrâneas nestas áreas ser baixa a moderada, a localização dos potenciais focos de
contaminação poderá ser responsável pelo aumento da vulnerabilidade nas duas bacias estudadas. Esta
metodologia demonstrou ser extremamente importante para um melhor conhecimento dos sistemas de
água subterrânea do Porto e, ainda, da hidrogeologia de áreas urbanas.
The increased development of urban areas poses a threat to the quality and quantity of groundwater. Porto City is a densely urbanized region dominated by granites, which constitute an anisotropic and heterogeneous fractured media. The main target of this work was to highlight the importance of hydrogeological mapping, as well as the vital significance of hydrogeological and potential contamination sources inventories to understand the vulnerability of Porto City groundwater systems. Such study was developed in Asprela and Massarelos drainage basins. An extensive groundwater inventory and also an inventory of potential contamination activities were documented in these areas. This study was supported by GIS technology, which was fundamental to a better understanding and integration over the study areas. Previously to the inventory implementation, a characterization of the drainage basins, regarding their geography, hydroclimatology, land use, geomorphology and hydrogeology, was performed. Both drainage basins are developed mostly in the hydrogeological unit granite, medium to fine grained, sometimes with saprolite. The hydrogeological inventory, mostly fountains and springs, included 8 water points in Asprela drainage basin and 21 in Massarelos drainage basin. Groundwaters are colorless, with no turbidity and no smell, acidic, with low to medium mineralizations, low temperatures and very low yields. Concerning potential contamination sources, 61 activities in Asprela drainage basin and 78 in Massarelos drainage basin were recognised. Most of these activities are point sources, namely school buildings and gas station/garages, although line sources have a significant spreading through both drainage basins. Although the intrinsic vulnerability to groundwater contamination is low to moderate in these areas, the location of the potential contamination sources may enhance the vulnerability in the study areas. This methodology demonstrated valuable in further broadening our knowledge of Porto City groundwater systems and also hydrogeology in urban areas.
The increased development of urban areas poses a threat to the quality and quantity of groundwater. Porto City is a densely urbanized region dominated by granites, which constitute an anisotropic and heterogeneous fractured media. The main target of this work was to highlight the importance of hydrogeological mapping, as well as the vital significance of hydrogeological and potential contamination sources inventories to understand the vulnerability of Porto City groundwater systems. Such study was developed in Asprela and Massarelos drainage basins. An extensive groundwater inventory and also an inventory of potential contamination activities were documented in these areas. This study was supported by GIS technology, which was fundamental to a better understanding and integration over the study areas. Previously to the inventory implementation, a characterization of the drainage basins, regarding their geography, hydroclimatology, land use, geomorphology and hydrogeology, was performed. Both drainage basins are developed mostly in the hydrogeological unit granite, medium to fine grained, sometimes with saprolite. The hydrogeological inventory, mostly fountains and springs, included 8 water points in Asprela drainage basin and 21 in Massarelos drainage basin. Groundwaters are colorless, with no turbidity and no smell, acidic, with low to medium mineralizations, low temperatures and very low yields. Concerning potential contamination sources, 61 activities in Asprela drainage basin and 78 in Massarelos drainage basin were recognised. Most of these activities are point sources, namely school buildings and gas station/garages, although line sources have a significant spreading through both drainage basins. Although the intrinsic vulnerability to groundwater contamination is low to moderate in these areas, the location of the potential contamination sources may enhance the vulnerability in the study areas. This methodology demonstrated valuable in further broadening our knowledge of Porto City groundwater systems and also hydrogeology in urban areas.
Description
Keywords
Hidrogeologia urbana Inventário hidrogeológico Focos de contaminação Bacias hidrográficas da Asprela e Massarelos Urban hydrogeology Hydrogeological and contamination sources inventories Asprela and Massarelos drainage basins