Résumé
As often in the Sahelian belt, recharge of the Continental Terminal water table near Niamey, Niger, is essentially due to rainfall infiltration through numerous temporary pools. Tritium content in rain over the past 40 years is reconstructed and used by a simple model to calculate the groundwater renewal rate according to measurements throughout the aquifer. This isotopic estimate (25 mm per year) is close to the hydrodynamical estimate.