Browsing by Author "Mansour, Reem"
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- Alterações espácio-temporais da vulnerabilidade das águas subterrâneas urbanas e perímetros de protecção nos aquíferos cristalinos fracturados da cidaPublication . Mansour, Reem; Afonso, Maria José Coxito; Freitas, LilianaThis study presents a spatiotemporal analysis of changes in groundwater vulnerability and the safeguard zones using an integrated, multidisciplinary, and GIS-based approach. The fractured hard-rock aquifer of Porto city in the surroundings of Paranhos and Salgueiros spring galleries was used as an experimental case study where the TIME–INPUT method was used for assessing the intrinsic vulnerability and the Time-Dependent model was used for assessing the sanitary safeguard zones. Two scenarios were compared: the end of the XIXth century when the water was still used for drinking, and there were no sanitary sewers, and the present day in the XXIst century, after the city's urban expansion. The vulnerability and the safeguard zones were completely assessed using flow travel time components, and the results are based on travel times rather than categories of unitless numbers. Dug-wells data were used to estimate the thickness of the fissured zone, the saturated zone, and the unsaturated zone. The historical land use map was reconstructed using a historic map from 1892. Then, GIS models were built to predict the recharge, groundwater vertical and horizontal travel time, and surface travel time. Several updated elements have been added to enhance the calculation of vulnerability in urban areas, such as the maps of hydraulic networks. The study shows that the TIME-INPUT method and the Time-dependent model apply to urban fractured hard-rock aquifers. The results indicate that the land use in the study area has changed over time with rapid growth in urbanization, and the most affected factor by this change are the recharge (INPUT Factor) and surface travel time. Areas around tectonic lineaments are the most vulnerable, and the overall spatiotemporal changes in vulnerability and the safeguard zones are small in the study area between the past and present time.