Implications of climate change on hydrological extremes in the Blue Nile basin: A review

• Studies focusing on historical and projected hydrologic extremes are reviewed.
• Discrepancy among research outputs is addressed.
• Blue Nile flow has not changed in the past five decades.
• The need to prudently consider sources of uncertainty is emphasized.

Study regionThe Blue Nile river basin in East Africa.Study focusThis review paper presents the current understanding of hydrological extremes in the Blue Nile River basin under historic and future climate conditions, largely drawing on research outputs over the past decade. Characteristics of precipitation and streamflow extremes, including historic trends and future projections, are considered.New hydrological insightsThe review illustrates some discrepancy among research outputs. For the historical context, this is partially related to the period and length of data analyzed and the failure to consider the influence of multi-decadal oscillations. Consequently, we show that annual cycle of Blue Nile flow has not changed in the past five decades. For the future context, discrepancy is partially attributable to the various and differing climate and hydrological models included and the downscaling techniques applied. The need to prudently consider sources of uncertainty and potential causes of bias in historical trend and climate change impact research is highlighted.