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Climate change enhances interannual variability of the Nile river flow


The human population living in the Nile basin countries is projected to double by 2050, approaching one billion1. The increase in water demand associated with this burgeoning population will put significant stress on the available water resources. Potential changes in the flow of the Nile River as a result of climate change may further strain this critical situation2,3. Here, we present empirical evidence from observations and consistent projections from climate model simulations suggesting that the standard deviation describing interannual variability of total Nile flow could increase by 50% (±35%) (multi-model ensemble mean ± 1 standard deviation) in the twenty-first century compared to the twentieth century. We attribute the relatively large change in interannual variability of the Nile flow to projected increases in future occurrences of El Niño and La Niña events4,5 and to observed teleconnection between the El Niño–Southern Oscillation and Nile River flow6,7. Adequacy of current water storage capacity and plans for additional storage capacity in the basin will need to be re-evaluated given the projected enhancement of interannual variability in the future flow of the Nile river.

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Figure 1: Topographic map of Eastern Africa and the Nile sub-basins.
Figure 2: Observed stream flows and rainfall, and moving averages for the mean and standard deviation for the Upper Blue Nile and Atbara basins.
Figure 3: Changes in moving averages for the mean and standard deviation, coefficient of variation, number of ENSO events and frequency distribution of flow over Eastern Nile basin using 18 CMIP5 GCMs.
Figure 4: Total current water storage in the Eastern Nile basin, and required changes in future storage to accommodate the effects of climate change.


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E.A.B.E. conceived the study, and supervised the design and implementation of research. M.S.S. performed the analyses of observational data and climate models. E.A.B.E. supervised interpretation of results. M.S.S. wrote the paper, with input from E.A.B.E. Both authors contributed to revisions of the manuscript.

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Correspondence to Mohamed S. Siam.

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The authors declare no competing financial interests.

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Siam, M., Eltahir, E. Climate change enhances interannual variability of the Nile river flow. Nature Clim Change 7, 350–354 (2017).

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