Abstract
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.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
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.
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.
Cazenove, E. d., 1971. Ondes phréatiques sinusoIdales. La Houille Blanche, Issue 7, pp. 601–616.
Clark, W., 1965. Computing the barometric effeciency of a well. Journal of Hydraulic Engineering, 93, pp. 93–98.
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.
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.
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.
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.
Ferris, J., 1952. Cyclic fluctuations of water level as a basis for determining aquifer transmissivity, Washington: US Geological Survey.
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.
Hsieh, P., Bredehoeft, J. & Farr, J., 1987. Determination of Aquifer Transmissivity From Earth Tide Analysis. Water Resources Research, 23(10), pp. 1824–1832.
Krivic, P., 1982. Transmission des ondes de marée à travers l’aquifère côtier de Kras. Geologie, 25(2), pp. 309–325.
Melchior, 1978. The Tides of the Planet Earth. Elmsford (N.Y.): Pergamon.
P. Melchior & B. Ducarme, 1989. L’étude des phénomènes de marée gravimétrique. Geodynamique, 4(1), pp. 3–14.
Petit, V. & Leforgeais, C., 2013. Evaluation de l’état quantitatif des masses d’eau souterraines de la Réunion, s.l.: BRGM / ONEMA.
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.
Service hydrographique et océanographique de la Marine, 1997. La marée. Brest: SHOM.
Toll, N. & Rasmussen, T., 2007. Removal of Barometric Pressure Effect and Earth Tides form Observed Water Levels. Groundwater, 45(1), pp. 101–105.
ZexuanXu, Basst, S., Hu, B. & S.C. Barret, 2016. Long distance seawater intrusion through a karst. Scientific reports, 6(32235).
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2020 Springer Nature Switzerland AG
About this paper
Cite this paper
Collignon, B. (2020). Earth Tide Effect in Karstic and Non-karstic Aquifers in the Guinea Gulf. In: Bertrand, C., Denimal, S., Steinmann, M., Renard, P. (eds) Eurokarst 2018, Besançon. Advances in Karst Science. Springer, Cham. https://doi.org/10.1007/978-3-030-14015-1_26
Download citation
DOI: https://doi.org/10.1007/978-3-030-14015-1_26
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-030-14014-4
Online ISBN: 978-3-030-14015-1
eBook Packages: Earth and Environmental ScienceEarth and Environmental Science (R0)