Preprints
https://doi.org/10.5194/egusphere-2025-130
https://doi.org/10.5194/egusphere-2025-130
04 Mar 2025
 | 04 Mar 2025

Climate change impacts on floods in West Africa: New insight from two large-scale hydrological models

Serigne Bassirou Diop, Job Ekolu, Yves Tramblay, Bastien Dieppois, Stefania Grimaldi, Ansoumana Bodian, Juliette Blanchet, Ponnambalam Rameshwaran, Peter Salamon, and Benjamin Sultan

Abstract. West Africa is projected to face unprecedented shifts in temperature and extreme precipitation patterns as a result of climate change. The devastating impacts of river flooding are already being felt in most West African countries, emphasizing the urgent need for comprehensive insights into the frequency and magnitude of floods to guide the design of hydraulic infrastructure for effective flood risk mitigation and water resource management. Despite its significant socio-economic and environmental impacts, flood hazards remain poorly documented in West Africa due to the data-related challenges. This study aims to fill this knowledge gap by providing a large-scale analysis of flood frequency and magnitudes across West Africa, focusing on how climate change may influence future flood trends. To achieve this, we have used two large-scale hydrological models driven by five bias-corrected CMIP6 climate models under two Shared Socioeconomic Pathways (SSPs). The Generalized Extreme Value (GEV) distribution was utilized to analyze trends and detect change points by comparing multiple non-stationary GEV models across historical and future periods for a set of 58 catchments. Both hydrological models consistently projected increases in flood frequency and magnitude across West Africa, despite their differences in hydrological processes representation and calibration schemes. Flood magnitude is projected to increase for 94 % of the stations, with some locations experiencing increases exceeding 45 % in magnitude. In addition, the majority of trends are starting from the historical period, under both SSP2-4.5 and SSP5-8.5. The findings from this study provide regional-scale insights into the evolving flood risks across West Africa and highlight the urgent need for climate-resilient strategies to safeguard populations and infrastructure against the increasing threat of flood hazards.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Journal article(s) based on this preprint

09 Sep 2025
Climate change impacts on floods in West Africa: new insight from two large-scale hydrological models
Serigne Bassirou Diop, Job Ekolu, Yves Tramblay, Bastien Dieppois, Stefania Grimaldi, Ansoumana Bodian, Juliette Blanchet, Ponnambalam Rameshwaran, Peter Salamon, and Benjamin Sultan
Nat. Hazards Earth Syst. Sci., 25, 3161–3184, https://doi.org/10.5194/nhess-25-3161-2025,https://doi.org/10.5194/nhess-25-3161-2025, 2025
Short summary
Serigne Bassirou Diop, Job Ekolu, Yves Tramblay, Bastien Dieppois, Stefania Grimaldi, Ansoumana Bodian, Juliette Blanchet, Ponnambalam Rameshwaran, Peter Salamon, and Benjamin Sultan

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-130', Anonymous Referee #1, 14 Apr 2025
    • AC1: 'Reply on RC1', Yves Tramblay, 13 May 2025
  • RC2: 'Comment on egusphere-2025-130', Anonymous Referee #2, 15 Apr 2025
    • AC2: 'Reply on RC2', Yves Tramblay, 13 May 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-130', Anonymous Referee #1, 14 Apr 2025
    • AC1: 'Reply on RC1', Yves Tramblay, 13 May 2025
  • RC2: 'Comment on egusphere-2025-130', Anonymous Referee #2, 15 Apr 2025
    • AC2: 'Reply on RC2', Yves Tramblay, 13 May 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Reconsider after major revisions (further review by editor and referees) (13 May 2025) by Maria-Carmen Llasat
AR by Yves Tramblay on behalf of the Authors (15 May 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (01 Jun 2025) by Maria-Carmen Llasat
RR by Anonymous Referee #1 (13 Jun 2025)
RR by Danlu Guo (17 Jun 2025)
ED: Publish subject to technical corrections (02 Jul 2025) by Maria-Carmen Llasat
AR by Yves Tramblay on behalf of the Authors (07 Jul 2025)  Manuscript 

Journal article(s) based on this preprint

09 Sep 2025
Climate change impacts on floods in West Africa: new insight from two large-scale hydrological models
Serigne Bassirou Diop, Job Ekolu, Yves Tramblay, Bastien Dieppois, Stefania Grimaldi, Ansoumana Bodian, Juliette Blanchet, Ponnambalam Rameshwaran, Peter Salamon, and Benjamin Sultan
Nat. Hazards Earth Syst. Sci., 25, 3161–3184, https://doi.org/10.5194/nhess-25-3161-2025,https://doi.org/10.5194/nhess-25-3161-2025, 2025
Short summary
Serigne Bassirou Diop, Job Ekolu, Yves Tramblay, Bastien Dieppois, Stefania Grimaldi, Ansoumana Bodian, Juliette Blanchet, Ponnambalam Rameshwaran, Peter Salamon, and Benjamin Sultan
Serigne Bassirou Diop, Job Ekolu, Yves Tramblay, Bastien Dieppois, Stefania Grimaldi, Ansoumana Bodian, Juliette Blanchet, Ponnambalam Rameshwaran, Peter Salamon, and Benjamin Sultan

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Latest update: 09 Sep 2025
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Short summary
West Africa is very vulnerable to rivers floods. Current flood hazards are poorly understood due to limited data. This study is filling this knowledge gap using recent databases and two regional hydrological models to analyze changes in flood risk under two climate scenarios. Results show that most areas will see more frequent and severe floods, with some increasing by over 45 %. These findings stress the urgent need for climate-resilient strategies to protect communities and infrastructure.
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