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Volume 29 Number 6
  • E-ISSN: 1365-2478

Abstract

A

The “Autorité des amenegements des valées des Voltas (AVV)” is establishing new rural settlements in the Volta valleys. First, a survey of available water supplies is performed. Economic aquifers in Precambrian terrains are deep (15–50 m) and usually occur in fractured zones accompanying faults. Such zones can be identified on aerial photographs, but their precise location on the ground is virtually impossible by visual means. Because of the small size of the aquifers, a location error of 5 m can make the difference between a productive well and a dry hole.

Traditionally, resistivity profiling has been used as the means of locating the fractured zones in the field. Our studies suggest that the task can be performed faster, cheaper and more accurately by VLF and EM methods. Because of the limited choice of transmitting stations reccivable in Upper Volta, the VLF method is not sufficiently sensitive to detect conductors with a strike between 45° and 105°. The results obtained with a multifrequency, horizontal‐loop EM (HLEM) system were satisfactory in all investigated areas. During the 1980 field season, 35 target areas were surveyed. Of the 24 holes drilled so far, 23 are productive.

The weathered layer is a source of distinctive HLEM anomalies, which are characteristic of the underlying rocks. Therefore, different interpretational procedures had to be developed for granitic and volcano‐sedimentary areas. Despite the high background level of in‐phase and quadrature components, which varied with thickness and conductivity of the weathered layer, aquifers could be detected at a depth greater than 30 m. Attempts were made to interpret the HLEM results quantitatively using two models: a three‐layer medium and a valley discontinuity. The latter model is more realistic, but more scale modelling will have to be performed to permit development of viable interpretational procedures. Meanwhile, phasor diagrams based on drilling and resistivity sounding data can be used to estimate the aquifer depth.

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2006-04-27
2024-04-19

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References

  1. Betz, J.E.1975, Test program with additional comments on the Max Min II electromagnetic system, APEX Parametrics Ltd, Markham , 34 p.
     [Google Scholar]
  2. Betz, J.E.1976, Considerations behind the making of a well‐rounded exploration system, APEX Parametrics Ltd, Markham , 14 p.
     [Google Scholar]
  3. Blanchot, A., Marcelin, J., Hottin, G., Ouedraogo, F.O. and Tabsoba, P.J.E.1975, Le potentiel minièr de la République de Haute‐Volta, Ouagadougou, Direction de la géologie et des mines, 366 p.
  4. Eadie, T.1979, Stratified earth interpretation using standard horizontal‐loop electromagnetic data, University of Toronto, Research in Applied Geophysics9, 37 p.
     [Google Scholar]
  5. Engalenc, M.1978, Methode d'étude et de recherche de l'eau souterraine des roches cristallines de l'Afrique de l'ouest, Bulletin du Comité interafricain d'études hydrauliques (C.I.E.H.)–série hydrogéologie, 318 p.
  6. Hottin, G. and Ouedraogo, F.O.1975, Notice explicative de la carte géologique à 1/1.000.000 de la République de Haute‐Volta, Ouagadougou , Direction de la géologie et des mines, 58 p.
     [Google Scholar]
  7. Jong, S.J. de, Dirks, F.J.H., Kikietta, A., Palacky, G.J. and Ritsema, I.L.1981, Experimentations de méthodes electromagnetiques appliquées à la recherche des eux souterraines en terrain de socle cristallin en Haute‐Volta, Bulletin du Comité interafricain d'études hydrauliques (C.I.E.H.)–série hydrogéologie44, 17–26.
    [Google Scholar]
  8. Kalpagé, F.S.C.P.1974, Tropical soils–Classification, fertility and management, The Macmillan Co. of India Ltd, Madras , 283 p.
     [Google Scholar]
  9. Meekes, S.1981, Geofysische metingen in het kader van grondwaterprospectie voor watervoorziening in Boven Volta, M.Sc. thesis, Rijksuniversiteit Utrecht.
  10. Palacky, G.J.1981, The airborne electromagnetic method as a tool of geological mapping, Geophysical Prospecting29, 60–88.
    [Google Scholar]
  11. Palacky, G.J. and Kadekaru, K.1979. Effect of tropical weathering on electrical and electromagnetic measurements, Geophysics44, 69–88.
    [Google Scholar]
  12. Ritsema, I.L.1980, Test van twee electromagnetische systemen (horizontale loop and VLF) als prospektiemethoden naar grondwater in een semi‐aride kristallijn gebied in Boven Volta, M.Sc. thesis, Rijksuniversiteit Utrecht, 82 p.
  13. Villegas‐garcia, C.J.1979, On the electromagnetic response of non‐uniform overburden layers: Scale model experiments, University of Toronto, Research in Applied Geophysics10, 45 p.
     [Google Scholar]
  14. Whitmire, M.G.1980, Geophysical activity in 1979, Geophysics45, 1563–1579.
    [Google Scholar]
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