Evaluating the Impacts of Climate Change on the Stream Flow Events in Range of Scale of Watersheds, in the Upper Blue Nile Basin

Abstract

The main focus on three watersheds in the upper Blue Nile. The study used the Representative concentration pathway (RCP) climate model scenarios with 50 km resolution. The CORDEX-Africa model output of RCP2.6 and RCP8.5 scenarios were used. The Parameter Efficient Semi Distributed Water Balance model (PED-WM) was calibrated and validated to project the climate change impacts on the stream flow events. The future climate projection results were presented by dividing in to three future time horizons of 2030s (2021–2040), 2060s (2051–2070) and 2090s (2081–2100). The bias corrected maximum and minimum temperature increases in all months and seasons in the selected watersheds. The change in magnitude in RCP8.5 emission was higher than RCP2.6 scenario. The study resulted considerable average monthly, seasonal and annual precipitation change variability in magnitude and direction. In 2030s, the average annual Stream flow projection decreases up to −32.18% for RCP2.6 and up to −19.44% for RCP8.5 scenarios. In 2060s also the average annual stream flow decreases by −12.3% and −32.18% for RCP2.6 and RCP8.5 emission scenarios, respectively. Similarly, in 2090 s, the average annual Stream flow change decreases by −20.67 and −51.78% for RCP2.6 and RCP8.5 respectively. For the future time horizon, the maximum Stream flow changes in wide range from (−56.4 to 81.1%) and minimum flow from (−61.72 to 8.17%) in both RCP2.6 and RCP8.5.