Koubodana et al. (2025) Spatial and Temporal Trend Analysis of Flood Events Across Africa During the Historical Period

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Identification

• Journal: Water
• Year: 2025
• Date: 2025-12-13
• Authors: Houteta Djan’na Koubodana, Mouhamadou Bamba Sylla, Moustapha Tall, Alima Dajuma, Jeremy S. Pal, Chris Lennard, Piotr Wolski, Wilfran Moufouma‐Okia, Bruce Hewitson
• DOI: 10.3390/w17243531

Research Groups

[Not specified in the provided text.]

Short Summary

This study analyzed the spatial and temporal distribution of historical flood events across Africa from 1927 to 2020, revealing a significant upward trend in flood frequency, fatalities, affected populations, and economic damage, primarily driven by extreme precipitation indices.

Objective

• To examine the spatial and temporal distribution of historical flood events across Africa from 1927 to 2020, focusing on fatalities, affected populations, and economic damage, and to identify key meteorological drivers.

Study Configuration

• Spatial Scale: Continental Africa, including Regional Economic Communities (RECs), individual countries (e.g., Nigeria, Ethiopia, Algeria, Angola, Mozambique), and 16 African capital cities.
• Temporal Scale: Historical flood events from 1927 to 2020; meteorological driver analysis from 1981 to 2019; flood return periods computed for up to 100 years.

Methodology and Data

• Models used:
  • Mann–Kendall test for trend assessment.
  • Pearson correlation analysis for identifying meteorological drivers.
  • Weibull, Gamma, Lognormal, Gumbel, and Logistic probability distribution models for flood frequency analysis and return period computation.
• Data sources:
  • Emergency Events Database (EM-DAT) for flood event data.
  • ERA5 (fifth generation of bias-corrected European Centre for Medium-Range Weather Forecasts Reanalysis) for reanalysis data.
  • CHIRPS (Climate Hazards Group InfraRed Precipitation with Stations) observational datasets for precipitation data.
  • Extreme precipitation indices calculated: Consecutive Wet Days (CWD), annual precipitation on very wet days (R95PTOT), and Annual Maximum Precipitation (AMP).

Main Results

• A significant upward trend in flood frequency and impact was observed across Africa from 1927 to 2020, with a slope above 0.50 floods per year.
• Positive trends (at 99% significance level with slopes ranging between 0.50 and 0.60 floods per year) were found in flood-related fatalities, affected populations, and economic damage across RECs, individual countries, and cities.
• Regions particularly affected include West Africa (Nigeria, Ghana), East Africa (Ethiopia, Kenya, Tanzania), North Africa (Algeria, Morocco), Central Africa (Angola, Democratic Republic of Congo), and Southern Africa (Mozambique, Malawi, South Africa).
• The CWD, R95PTOT, and AMP indices were identified as reliable predictors of flood events.
• Non-stationary return periods exhibited low uncertainties for events within 20 years.

Contributions

• Provides a comprehensive, long-term (1927-2020) spatial and temporal analysis of flood events and their impacts across the entire African continent.
• Quantifies significant upward trends in flood frequency, fatalities, affected populations, and economic damage at various scales (continental, regional, national, city).
• Identifies and validates key extreme precipitation indices (CWD, R95PTOT, AMP) as reliable meteorological drivers for flood events in Africa.
• Applies multiple probability distribution models for robust flood frequency analysis and return period calculations, including insights into non-stationary return periods.
• Underscores the urgent need for enhanced flood disaster management strategies, improved forecasting systems, and resilient infrastructure in Africa.

Funding

[Not specified in the provided text.]

Citation

@article{Koubodana2025Spatial,
  author = {Koubodana, Houteta Djan’na and Sylla, Mouhamadou Bamba and Tall, Moustapha and Dajuma, Alima and Pal, Jeremy S. and Lennard, Chris and Wolski, Piotr and Moufouma‐Okia, Wilfran and Hewitson, Bruce},
  title = {Spatial and Temporal Trend Analysis of Flood Events Across Africa During the Historical Period},
  journal = {Water},
  year = {2025},
  doi = {10.3390/w17243531},
  url = {https://doi.org/10.3390/w17243531}
}