EGU24-10459, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Past, Present, and Future Impacts of Climate Change and Variability on Flood Hazards in Sub-Saharan Africa

Job Ekolu1, Bastien Dieppois1, Yves Tramblay2, Jonathan Eden1, Moussa Sidibe3, Gabriele Villarini4, Simon Moulds5, Louise Slater6, Stefania Grimaldi7, Peter Salamon7, Pierre Camberlin8, Benjamin Pohl8, Gil Mahé9, and Marco van de Wiel1
Job Ekolu et al.
  • 1Coventry University, Centre for Agroecology, Water and Resilience (CAWR), Coventry, United Kingdom of Great Britain – England, Scotland, Wales (
  • 2Espace-Dev, Univ. Montpellier, CNRS, IRD, Montpellier, France
  • 3Global Facility for Disaster Reduction and Recovery (GFDRR), World Bank, Washington DC, USA
  • 4Department of Civil and Environmental Engineering and High Meadows Environmental Institute, Princeton University, Princeton, New Jersey, USA 
  • 5School of GeoSciences, University of Edinburgh, UK
  • 6School of Geography and the Environment, University of Oxford, Oxford, UK
  • 7European Commission, Joint Research Centre, Ispra, Italy
  • 8Centre de Recherches de Climatologie, UMR 6282 Biogéosciences CNRS/Université de Bourgogne Franche-Comté, Dijon, France
  • 9HSM, Univ. Montpellier, CNRS, IRD, Montpellier, France

Sub-Saharan Africa (SSA) is strongly affected by flood hazards, which endanger human lives and disrupt economic stability. It is therefore critical to further understand the potential impact of climate change and variability on historical and future flood hazards in SSA. To do so, we first reconstructed a complete 65-yearlong daily streamflow, presenting over 600 stations distributed throughout SSA. Using this new dataset, we found that historical trends in flood frequency, duration, and intensity were strongly modulated by decadal to multidecadal variability. We then identified internal modes of climate variability in the Pacific and Indian Oceans as primary drivers of decadal variations in flood occurrence in southern and eastern Africa. Meanwhile, decadal sea-surface temperature anomalies (SSTa) over the eastern Mediterranean region and the North Atlantic were primarily driving decadal trends in floods occurring over western and central Africa. Using 12 climate model large ensembles from the Coupled Model Intercomparison Project Phases 5 and 6 (CMIP5 and 6), we also found such decadal variations in SSTa in the Mediterranean Atlantic, Pacific, and Indian oceans could modulate the occurrence of flood hazards by up to 50% in SSA during the 21st century. Finally, combining bias-corrected CMIP6 data and the open-source hydrological model LISFLOOD, we examine the potential impact of climate change on future trends affecting the intensity, frequency, and duration of floods in West Africa. This study therefore enabled us to compare for the first time the relative importance of climate change and climate variability on future changes affecting flood hazards in SSA.

How to cite: Ekolu, J., Dieppois, B., Tramblay, Y., Eden, J., Sidibe, M., Villarini, G., Moulds, S., Slater, L., Grimaldi, S., Salamon, P., Camberlin, P., Pohl, B., Mahé, G., and van de Wiel, M.: Past, Present, and Future Impacts of Climate Change and Variability on Flood Hazards in Sub-Saharan Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10459,, 2024.