Résumé
Rainfall and flow data were collected and updated in equatorial Cameroon, notably for the 1990s. Rainfall, runoff and runoff coefficients were analysed at different time-scales: monthly, seasonal and annual, using graphical and statistical techniques to identify trends and changes in time series. The results show that the annual rainfall and runoff values declined during the acute drought periods of 1972-1973 and 1983-1984. The most significant climatic variation resulted from rainfall change during dry seasons, which over the long term induce a tendency for change to the regime of the annual hydrological cycle. The reduction of rainfall during the boreal winter dry season (Dec ember-February), creates an more important hydrological deficit that leads to lower runoff coefficients during the boreal spring rainfall (March-June). Conversely, the enhancement of flows during autumn (September-November), while the autumn rainfall does not significantly AA change, is probably linked to the increase of rainfall during the summer dryseason (July-August) for several decades, which keeps the soil more humid and favours runoff at the beginning of the autumn flood.