Nile basin flow regimes under 21st century climate variability

Abstract

The Nile Basin, a freshwater resource for over 300 million people, faces unprecedented hydrological risks under climate change and transboundary water disputes. Yet, basin-wide projections of extreme streamflow events remain limited by fragmented modeling and insufficient integration of climate uncertainty. Here, we assess future flood risk in downstream countries using a calibrated, climate-driven Soil and Water Assessment Tool model, forced by bias-corrected CMIP6 models under the SSP2-4.5 and SSP5-8.5 scenarios, marking the first application of its kind targeting the Nile Basin downstream regions. Our results indicate a 63% (SSP2-4.5) and 85% (SSP5-8.5) increase in 100-year peak discharges in the 21st century, with extreme floods occurring nearly every decade under high-emission scenarios. Our climate-driven hydrologic modeling, risk analysis, and climate projections emphasize the need for coordinated planning, provide actionable risk information, and a framework for regional cooperation and preparedness to mitigate future flood risks and address water security challenges in the Nile Basin.