The Dynamics of Hydrological Extremes under the Highest Emission Climate Change Scenario in the Headwater Catchments of the Upper Blue Nile Basin, Ethiopia

Climate change and its impact on surface runoff in the upper Blue Nile basin sub-basins have been widely studied future climate projections. However, extreme flow events of rivers is barely investigated discretely. In this paper, temperature rainfall under Representative Concentration Pathway (RCP) highest emission scenario (RCP 8.5) high low simulated by Soil Water Assessment Tool (SWAT 2012) major watersheds Lake Tana Basin has evaluated comparing baseline period (1971–2000) with 2020s (2011–2040), 2050s (2041–2070), 2080s (2071–2100). The flows were selected Annual Maximum Series (AMS) model, whereas low-flow 7-day sustained mean annual minimum method. result showed that maximum ranged from 2.93 °C to 5.17 monthly time scales 2080s. increment also more prominent it expected rise 4.75 °C. Inter-annual variability shown increasing decreasing patterns. increments are 22.37%, 25.58%, 29.75% 2020s, 2050s, 2080s, respectively, projected decrease dictates 6.42%, 7.11%, 9.26% respectively. Due changes rainfall, likely 8.39%, 8.33%, 6.21%, 5.02% Ribb, Gumara, Megech, Gilgel Abay watersheds, Abay, Ribb increase 13.94%, 12.16%, 10.90%, 10.24%, every 30 years.