Investigation of drought and flooding areas in coastal countries of West Africa in the context of global warming

This study aims to investigate drought and flooding area in West Africa during the pre-industrial and projected future periods. The datasets used consist of CHIRPS-2 and CRU for observed reanalysis and CORDEX/CMIP6 for climate model scenarios. The CORDEX/ CMIP6’s potential evapotranspiration (PET) and precipitation correlate well with observation dataset over the study area with respective KGE up to 0.75 and 0.9. The pre-industrial period used in this research covers 1971-2000, while the projection period is defined according to the global warming level and the RCPs. Results showed that, the spatial and temporal repartition of SPEIs was elucidated by applying the Empirical Orthogonal Function (EOF) analysis, which showed that during the pre-industrial period, the wettest areas were located at the eastern and southern part of West Africa. The analyses on projected scenarios reveals that most of the coastal countries in Gulf of Guinea will be globally wetter under all the GWLs studied, with some interleaving as coastal countries (Senegal, Ivory-Coast, Benin, Togo and Nigeria). Some years will experiment extreme drought, whilst Savanna will get positive changes, which will lead them to become less dry compare to period 1971-2000. An investigation on the spatial concentration of precipitation using precipitation concentration index (PCI), have involved this study to highline an uniform spatial distribution of annual and wet season precipitations over gulf of Guinea and Savanna, follow by an increasing of uniform and moderate spatial distribution of precipitation under RCP4.5, and negative changes over eastern and western part of the study area for projection RCP8.5, explaining the high variability of concentration of precipitation over these regions.

Keywords: Drought and flood area, climate model, West Africa, global warming