Résumé
Numerous chemical analyses undertaken during the last 4 a in the Niamey area of the Continental Terminalgroundwaters (SW Niger, Africa) reveal large seasonal variations and high NO3 content (up to 2.87 meq/l). The positivecorrelation between conductivity and depth to the water table indicates that the chemical change is associated withthe recharge. In the shallow wells, this highly mineralised recharge reflects the rain composition, variably concentratedby evaporation processes.