Zakaria M. G., Taupin Jean-Denis, Ranaivoarisoa A., Robison L. R. (2015). Caractérisation géochimique et bactériologique des nappes d'une région à climat tropical sec au centre Sud de Madagascar = Geochemical and bacteriological characterization of aquifers in a dry tropical region in south central Madagascar. Hydrological Sciences Journal = Journal des Sciences Hydrologiques, 60 (4), p. 746-759. ISSN 0262-6667.
Titre du document
Caractérisation géochimique et bactériologique des nappes d'une région à climat tropical sec au centre Sud de Madagascar = Geochemical and bacteriological characterization of aquifers in a dry tropical region in south central Madagascar
Zakaria M. G., Taupin Jean-Denis, Ranaivoarisoa A., Robison L. R.
Source
Hydrological Sciences Journal = Journal des Sciences Hydrologiques, 2015,
60 (4), p. 746-759 ISSN 0262-6667
The district of Betroka, subjected to a dry tropical climate, experiences severe water resource problems. For many inhabitants, this situation results in the consumption of water of very bad quality in terms of both its physical chemistry and bacteriology. Therefore, to improve this situation, the Malagasy government planned to undertake a programme of drinking water supply and purification in rural areas (a project of 350 drillings), as part of which the present work has been carried out, to obtain water for human consumption of acceptable quality in terms of bacteriology and mineralization. The microbiological study of the groundwater of the district of Betroka confirmed the bacteriological purity because it does not contain bacteria of fecal origin. The hydrochemical study revealed different processes leading to the mineralization of the groundwater in relation to: (a) the ascent of the saline water of deep origin along the transverse fractures of the major shearing of Betroka, along the normal faults at the origin of the graben of the Mangoky, and of the domain of the massif in dome and basin of the intrusive complex of Ianakafy; (b) the dissolution of the aerosols and sea spray deposited, dissolved by the rain and integrated into the aquifers; and (c) the interaction between meteoric water and groundwater with mineral rocks (scapolite, phlogopite, biotite, hornblende, etc.) could also contribute to the strong mineralization.
