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Groundwater flow system analysis in the regolith of Dodowa on the Accra Plains, Ghana

Foppen, J. W.; Lutterodt, G.; Rau, G. C.; Minkah, O.

Abstract:
Study Region: Accra Plains. Study Focus: We conducted a field geology mapping, a well inventory exercise, used ERT, drilled boreholes at 8 locations (15–60 m depth), took drill core samples which we subjected to dilute acid leaching experiments, installed piezometers and equipped them with pressure transducers, analyzed tidal signals in high frequency groundwater hydrographs, carried out pumping tests, and, finally, took 49 groundwater samples. New Insights: Our results indicated a diverse groundwater system. On the one hand, groundwater was found at shallow depths in the saprolite of the Togo Structural Unit (TSU), which, in unweathered state, is composed of phyllites, schists, and quartzites. This system was shallow and predominantly unconfined, as revealed by tidal analysis. In addition, transmissivities of TSU saprolite, all in the order of < 6e-5 m2/s, reduced with depth, which indicated either the lack of a stratiform fractured layer or the presence of such layer beyond drilled depths. On the other hand, groundwater was found in fractures of the gneisses of the Dahomeyan Structural Unit (DSU). This system was potentially deeper, but DSU transmissivities were significantly lower than those of TSU saprolite. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000105855
Veröffentlicht am 24.02.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Geowissenschaften (AGW)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 04.2020
Sprache Englisch
Identifikator ISSN: 2214-5818
KITopen-ID: 1000105855
Erschienen in Journal of hydrology / Regional studies
Band 28
Seiten Article: 100663
Projektinformation SubTideTools (EU, H2020, 835852)
Schlagwörter Weathered basement, Saprolite, Local groundwater systems, Groundwater tidal analysis, Waste water infiltration
Nachgewiesen in Scopus
Web of Science
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