Abstract
The objective of this article is to study climate change in the Ogooue watershed: recent evolution and impact on flows. For this, the hydropluviometric data of this basin were analyzed using the Pettitt test. The results of this study reveal a statistically significantdecrease in runoff that the Pettitt test situates in 1972-73, but nothing like that for rainfallat this same time scale. The decadal deviations from the inter-annual average, however, show clearer links between these variables, resulting mainly in a synchronous decrease during the 1970s and 1980s. This decrease is followed byanincreaseduring the 1990s and 2000s, which diminished again during the 2010s. The flows of the rainy seasons (spring and autumn) recorded the most significant modifications, following variations in the rainfall patterns of the dry seasons (winter and summer) that precede them. The winter dry season recorded a significant decrease in rainfall between the decades 1970 and 1990, which caused a drop in spring flows. The increasingand decreasing respectively noted during the 2000s and 2010s are accompanied by the same trends in the spring flows. Conversely, between the decades 1980 and1990,there was a joint increase in summer rainfall and autumn flows. The decrease in summer rainfall observed since the 2000s is also noticeable in the autumn flows. These results could be used to strengthen water resources management capacities in the watershed concerned and the region. They also provide new insights to study and understand seasonal variation and availability of freshwater downstream, in estuaries and coastal areas of regional rivers.