Browsing by Author "Dala, V."
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- Contribuição do método geofísico eletromagnético no domínio de tempo para o estudo dos sistemas aquíferos multicamada transfronteiriços da bacia do Kalahari, Cunene, AngolaPublication . Francés, Alain Pascal; Ramalho, Elsa; Santos, Fernando Monteiro; Llorente, J.; Mateus, T.; Cuervo, I.; Lobón, Jose Luis Garcia; Dala, V.; Ditutala, M.; Victorino, Américo da MataSUMMARY: Under the scope of project PLANAGEO, a geophysical survey using the time domain electromagnetic (TDEM) method was planned and conducted. This survey aimed to contribute to the hydrogeological conceptual model of the KOS and KOH aquifer systems, to validate the 1960 data electrical resistivity reprocessing and to define the future location of deep boreholes. The TDEM survey allowed identifying different layers with different geoelectric characteristics and assigning electrical resistivity characteristics to each hydrogeological feature of the aquifer systems. These assumptions were found adequate, and the results were used to define the drilling locations of 5 wells.
- Contribution of the time domain electromagnetic method to the study of the Kalahari transboundary multilayered aquifer systems in Southern AngolaPublication . Francés, Alain Pascal; Ramalho, Elsa; Santos, Fernando Monteiro; Llorente, J.; Mateus, T.; Martín-Banda, Raquel; Cuervo, I.; Lobón, Jose Luis Garcia; Dala, V.; Ditutala, M.; Famorosa, A.; Victorino, Américo da MataABSTRACT: The Cunene Province (Southern Angola) is facing recurrent and pluriannual droughts. Surface water supply could be reinforced using the groundwater resources of the multilayered aquifer systems (MAS) hosted in the siliciclastic sediments of the Kalahari Group. The MAS were first identified in the early 2000s in Northern Namibia and recently in the Cunene Province, by studies of the PLANAGEO project based on modern processing and reinterpretation of legacy data from the 1960s and 1970s (electrical resistivity data and deep boreholes). This article presents the results of a time domain electromagnetic (TDEM) survey conducted in the Cunene Province to: (i) contribute to the design of the hydrogeological conceptual model of the transboundary MAS, namely their geometry and extension; (ii) validate the reprocessing of the legacy data; and (iii) guide the future location of boreholes. Results depict the geometry of the sedimentary basin and the characterization of the MAS, with particular emphasis on the intermediate and deep aquifers. The borehole siting, based on the interpretation of the new TDEM data and the legacy data (clay markers in borehole logs), was successful, with a good agreement between estimated and observed horizons of the deep aquifers. However, the presence of clayey layers, a clay-rich matrix in the detrital deposits and saline/brackish groundwater led to uncertainties in the interpretation of the electrical transects. As such, recommendations are made to improve future data collection and mapping of the MAS.