Le cordon sableux Limani-Yagoua, extrême-nord Cameroun, et son rôle hydraulique |
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| Authors: | B Ngounou Ngatcha J Mudry A Wakponou GE Ekodeck R Njitchoua J Sarrot-Reynauld |
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| Institution: | a Université de Ngaoundéré, Département des Sciences de la Terre, BP 454 Ngaoundéré, Cameroun;b Equipe d'Accueil Géosciences, Déformation, Ecoulement, Transfert, la Bouloie, 25030 Besançon, France;c Université de Ngaoundéré, Département de Géographie, BP 454 Ngaoundéré, Cameroun;d Université de Yaoundé I, Département des Sciences de la Terre, BP 812 Yaoundé, Cameroun;e Laboratoire d'Hydrologie et de Géochimie Isotopique, Bat 504, Université Paris sud, 91405 Orsay, France;f Institut Dolomieu, Rue Maurice Gignoux, Grenoble, France |
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| Abstract: | The Limani-Yagoua mega sand-ridge, covering an area of 330,000 km2 is well know in the extreme north of Cameroun. Similar structures have also been described in the Chad Republic (Bongor-Koro-Toro), Niger (Tal) and Nigeria (Bama). Two possible origins can be considered: (i) circum-lacustrine around the Lake Chad Basin, interpreted as a Holocene or Pleistocene palæo-shoreline, or (ii) æolian accumulation as a mega sand dune in an area of basin subsidence. The sand-ridge in northern Cameroun is an extremely permeable aquifer with discharge rates of 3–6 m3 h−1. High nitrate levels (27–127 mg l−1) have been observed in several boreholes. Tritium at 4.1 ut indicates recent groundwater recharge, suggesting infiltration of rainfall damned by the sand-ridge. |
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