Floods of the Nile in the past can help us for the future

The iconic floods of the Nile River are often associated to the development of irrigation and agriculture in pharaonic Egypt. However, even today, seasonal rainfall and flooding remain crucial to sustain large populations in the Nile Valley, from the Equator to the Mediterranean coast. Climate models predict a large increase in monsoonal rainfall in this region due to global warming for all climatic scenarios. To address these threats in the future, it is important to understand how major river systems will respond to increased rainfall. Insights can be gained from studying ancient times that are known to have been wetter and warmer than the present time.

To gain access to these ancient times, Cécile Blanchet and colleagues from the GFZ German Research Centre for Geosciences, Monica Ionita (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, AWI) and Arne Ramisch (University of Innsbruck) have analyzed a unique sediment core. It comes directly from the mouth of the Nile and records seasonal flooding from the North African wet period eleven to six thousand years ago. These brought with them varying amounts of fluvial particles, which were preserved in the form of fine layers. 

The analyses reveals that wetter climates led to very strong and weak floods and a highly instable river system, which may have rendered the Nile valley uninhabitable. Although intensified, flood variability was paced by similar climatic forcing as today, operating on annual to multi-decadal timescales. Data from the past could help to make the occurrence of such extreme events more predictable, which can help to reduce the risks to local populations through reliable forecasting tools and adequate infrastructure.

Press release of the GFZ

Original publication:

Blanchet, C.L., Ramisch, A., Tjallingii, R. et al. Climatic pacing of extreme Nile floods during the North African Humid Period. Nat. Geosci. (2024). https://doi.org/10.1038/s41561-024-01471-9