Impacts of global changes on water resources in the Sahel of West Africa

The objective of this study is to assess the impacts of global changes on the future runoff at the Wayen gauging station on the Upper Nakanbe River in Burkina Faso with a view of water resources planning. The specific objectives were to: (i) elaborate climate and socio-economic scenarios up to 2025 (period 2011-2040); (ii) Build the time series of soil water holding capacity; (iii) implement a hydrological model (GR2M) taking into account environmental change. The results indicated an increase of the soil reservoir capacity of the model linked to socio-economic impacts (intensive recovery of degraded soils). In terms of annual rainfall and evapotranspiration, the projections of regional climate models (RCMs) used vary respectively in a range from -3 to +10% and +2 to +7% in relation to the reference period 1971-2000. According to the climate scenarios, hydrological simulation shows that flows will change more or less strongly in the future with the annual rate ranging from -6 to +22%.