Journal des sciences de la Terre et du changement climatique

Abstrait

Climate Change Impacts on the Ou é m é River, Benin, West Africa

Gilles RC Essou and Francois Brissette

The present study identifies the future impacts of climate change on the flows of the Ouémé River in Bonou, for the 2035-2064 and 2070-2099 periods. For this identification, a set of 65 climate projections from 24 climate models, based on three greenhouse gas emissions scenarios (A2, B1 and A1B) was used. Hydrologic simulations were carried out with a lumped conceptual hydrology model. The results obtained from this study show that daily temperatures in the Ouémé catchment over the reference period (1971-2000) will raise by up to 5°C during the 2070-2099 horizon. For their part, mean daily precipitation projections are much more uncertain. However, what is clear is that mean monthly flows will see a drop potentially as high as 30% during the rainy season, and 20% during the dry season. Similarly, mean seasonal and annual flows will drop by as much as 8 to 10% and 3 to 5%, respectively. This drop will also affect maximum annual flows at a proportion of approximately 3% in the 2035-2064 period and of 5% between 2070 and 2099. This study also showed that we will be seeing changes in extreme flows. These changes will be characterized by a slight drop in quantiles for return periods of less than 10 years, and a potential increase of up to 100 m3/s (an increase of approximately 6%) for quantiles of the return period of 100 years covering the 2070-2099 horizon. These changes have impacts on the economic activities and on the water resource availability in the catchment.