Affiliation: | 1. Department of Earth Sciences, Faculty of Science, University of Yaoundé 1, PO Box: 812, Yaoundé, Cameroon;2. Department of Mines, Advanced School of Engineering of Antananarivo, University of Antananarivo, PO Box: 566, Madagascar;3. Institute of Geological and Mining Research (IRGM), Hydrological Research Centre, P.O. Box: 4110, Yaoundé, Cameroon |