Résumé
The effects of climate changes on river baseflow and aquifer storage have been investigated using hydrological and rainfall data bases of the Central African Republic from 1902 to 1994. A decrease in runoff, observed every where, coincides with a decrease in rainfall with a time lag of 3 years. Compared with previous droughts, these recent periods of low rainfall and runoff (from 1971 to the present) are exceptionally long. As a consequence, the annual hydrograph in Oubangui has been significantly reduced in volume but not in duration, causing lowering of the groundwater table. A distinct break in time series of rainfall and runoff was detected. The prolonged period of low rainfall irreversibly changed infiltration patterns and sustainability of river flows, with a marked difference on a regional scale. In the north, the part of runoff deficit infiltrating and recharging groundwater reserves has diminished.