Speaker
Description
Adapting to climate change in West Africa, including the design of water-management and soil-conservation works, requires a reliable picture of past and future rainfall extremes. This study characterises rainfall extremes in Burkina Faso, explores their statistical association with crop yields and examines their projected evolution. Rainfall extreme indices were computed over the June–September season from two satellite products, CHIRPS and TAMSAT, analysed separately over 1983–2012. Eight CMIP6 models, bias-corrected by quantile delta mapping, were used under SSP2-4.5 and SSP5-8.5 for 2021–2050. Associations with regional yields of maize, millet, sorghum and groundnut were tested over 1996–2012 (17 years) using Spearman correlations with false-discovery-rate (FDR) correction. Both products agree on the south–north gradient of seasonal rainfall (623 mm for CHIRPS, 589 mm for TAMSAT) but differ in temporal structure: CHIRPS shows 42% higher wet-day intensity and 50% longer maximum dry spells. Both indicate rising seasonal rainfall and shorter dry spells over 1983–2012. Consecutive dry days (CDD) is the index most strongly associated with millet and sorghum yield anomalies, with a counter-intuitive sign: yields are lower in years with the shortest dry spells. This association is significant after FDR correction by index family only with TAMSAT (millet: Spearman r = 0.71, q = 0.017); it is weaker with CHIRPS and not significant under a global correction. In CMIP6, heavy-rainfall indices increase consistently across models, whereas regional changes remain highly uncertain. These findings are exploratory and do not support operational recommendations. They show that conclusions on rainfall extremes depend on the satellite product, and underline the need for station data and for soil–water modelling to inform climate-adaptation measures and earthworks design.
Mots-clés (5) : Burkina Faso; rainfall extremes; climate-change adaptation; CMIP6; crop yields