Earth Tide Effect in Karstic and Non-karstic Aquifers in the Guinea Gulf

  • Bernard CollignonEmail author
Conference paper
Part of the Advances in Karst Science book series (AKS)


During long-term pumping tests in Gabon and Benin, we were surprised to observe large-amplitude tidal signals in boreholes located more than 20 km from the sea. This article describes these tidal signals (maximum amplitude, variation in time and space, phase shift, etc.) and attempts to interpret them. The signal amplitude varies considerably from one aquifer to another (from 2 mm to 110 cm) but is uniform within an aquifer and constitutes a signature. We are therefore seeking to use this signature to characterize the transmissive or capacitive properties of each aquifer. The use of this tool is limited by the difficulty of isolating the piezometric tidal signal among other phenomena that can mask it (pumping, rain, seasonal drying, etc.). Once the tidal signal is properly isolated, it can be used as an indicator of the risk of seawater intrusion. This concern is particularly acute if the aquifer consists of karstified rocks, as the intrusion is likely to extend several kilometres inland. It is therefore essential to be able to distinguish three situations with different levels of risk. Two of these situations have been relatively well documented: earth tides that do not raise a risk of seawater intrusion and ocean tides, which induce a very high risk of karst aquifers in direct contact with the sea. A third case should be added: that of ocean tides that induce periodic pressure variations in captive aquifers. The risk of seawater intrusion is then moderate, even when this tidal signal is very spectacular, as in some confined karst aquifers in Benin.


Karst Earth tide Ocean tide Tidal signal measurement and compensation Seawater intrusion 


  1. Bélanger, C., 2000. Modélisation numérique d’un essai d’aquifère dans un aquifère à nappe captive soumis à l’effet de marée. Mémoire de Maîtrise ès Sciences Appliquées éd. Montréal: Ecole Polytechnique de Montreal. Google Scholar
  2. Boussinecq J. 1904. Recherches théoriques sur l’écoulement des nappes d’eau infiltrées dans le sol et sur le débit des sources. Journal de mathématiques appliquées, fasc.1.Google Scholar
  3. Cazenove, E. d., 1971. Ondes phréatiques sinusoIdales. La Houille Blanche, Issue 7, pp. 601–616.Google Scholar
  4. Clark, W., 1965. Computing the barometric effeciency of a well. Journal of Hydraulic Engineering, 93, pp. 93–98.Google Scholar
  5. Collignon, B., 1992. Données nouvelles sur l’aquifère paléocène du bassin sédimentaire côtier bénino-togolais. Neuchâtel, 5ème Colloque d’hydrologie en pys calcaire et milieu fissuré.Google Scholar
  6. Collignon, B. & Ondo, C., 2016. Managed Aquifer Recharge (MAR) to Supply Libreville, a Water-Stressed City (Gabon). Dans: P. R. &. C. Bertrand, éd. Eurokarst 2016 - Advances in the Hydrogeology of Karst and Carbonate Reservoirs. Neufchatel: Springer, pp. 273–281.Google Scholar
  7. Cooper, H., Bredehoeft, J. & Papadopulos, L., 1965. The response of well-aquifer systems to seismic waves. Journal of Geophysical Research, 70 (6), pp. 3915–3926.Google Scholar
  8. Cuello, J., Guarracino, L. & L.B. Monachesi, 2017. Groundwater response to tidal fluctuations in wedge-shaped confoned aquifers. Journal of hydrogeology, Volume 25, pp. 1509–1515.Google Scholar
  9. Ferris, J., 1952. Cyclic fluctuations of water level as a basis for determining aquifer transmissivity, Washington: US Geological Survey.Google Scholar
  10. Grillot, J.-C., Clezio, M. L. & Bodoyan, A., 2015. Filtrages piézométriques préliminaires à l’analyse du comportement des eaux souterraines lors des crises sismiques: exemple dans le petit Caucase. Hydrological Science Journal, 40(5), pp. 647–662.Google Scholar
  11. Hsieh, P., Bredehoeft, J. & Farr, J., 1987. Determination of Aquifer Transmissivity From Earth Tide Analysis. Water Resources Research, 23(10), pp. 1824–1832.Google Scholar
  12. Krivic, P., 1982. Transmission des ondes de marée à travers l’aquifère côtier de Kras. Geologie, 25(2), pp. 309–325.Google Scholar
  13. Melchior, 1978. The Tides of the Planet Earth. Elmsford (N.Y.): Pergamon.Google Scholar
  14. P. Melchior & B. Ducarme, 1989. L’étude des phénomènes de marée gravimétrique. Geodynamique, 4(1), pp. 3–14.Google Scholar
  15. Petit, V. & Leforgeais, C., 2013. Evaluation de l’état quantitatif des masses d’eau souterraines de la Réunion, s.l.: BRGM / ONEMA.Google Scholar
  16. Rojstaczer, S. & Riley, F., 1990. Response of the Water Level in a Well to Earth Tides and Atmospheric Loading under Unconfined Conditions. Water Resource Research, 26(8), pp. 1803–1817.Google Scholar
  17. Service hydrographique et océanographique de la Marine, 1997. La marée. Brest: SHOM.Google Scholar
  18. Toll, N. & Rasmussen, T., 2007. Removal of Barometric Pressure Effect and Earth Tides form Observed Water Levels. Groundwater, 45(1), pp. 101–105.Google Scholar
  19. ZexuanXu, Basst, S., Hu, B. & S.C. Barret, 2016. Long distance seawater intrusion through a karst. Scientific reports, 6(32235).Google Scholar

Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  1. 1.UrbaconsultingChateauneuf de GadagneFrance

Personalised recommendations