Research Article
Climate Change Impacts on Hydrology of Jemma River Sub Basin, Upper Blue Nile, Ethiopia
Yimer Assefa Yimam*
,
Brook Abate
Issue:
Volume 13, Issue 3, September 2025
Pages:
174-199
Received:
6 June 2025
Accepted:
30 June 2025
Published:
19 July 2025
DOI:
10.11648/j.hyd.20251303.11
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Abstract: Understanding the potential impacts of climate change on hydrological processes and water resources at regional and local scales is essential for developing effective adaptation strategies. This study evaluates the projected effects of climate change on the Jemma River Basin, located in the Upper Blue Nile region of Ethiopia, using future climate data derived from the second-generation Canadian Earth System Model (CanESM2) under three Representative Concentration Pathways (RCP2.6, RCP4.5, and RCP8.5). The climate projections were downscaled and bias-corrected at the catchment level using observed station data from within the basin. Hydrological modelling was conducted using the Soil and Water Assessment Tool (SWAT), while model calibration and validation were carried out with the SUFI2 algorithm in the SWAT-CUP framework. The calibration phase produced performance metrics of R² = 0.83 and NSE = 0.69, while validation results were R² = 0.84 and NSE = 0.71 for monthly streamflow simulations. To evaluate future climate-induced changes, percentage variations in precipitation, potential evapotranspiration (PET), streamflow, and temperature were analyzed for three future periods 2030s (2021-2040), 2060s (2051-2070), and 2090s (2081-2100) relative to the baseline period (1991-2010). Under RCP2.6, annual, seasonal, and monthly rainfall is generally projected to increase, except during the Kiremt (JJAS) season in the 2060s and 2090s. For RCP4.5 and RCP8.5, rainfall is expected to increase consistently across all future periods. PET projections under RCP2.6 suggest increases during Kiremt and Bega (ONDJ) but declines during Belg (FMAM). In contrast, PET is projected to rise annually and during Bega and Belg seasons under RCP4.5, with a decrease during Kiremt. For RCP8.5, PET is expected to decrease on an annual basis and during Bega and Belg, but increase in Kiremt. Temperature projections indicate a consistent upward trend across all scenarios and timeframes. Regarding streamflow, results show an increase during Belg, whereas annual, Kiremt, and Bega flows are projected to decline under all RCP scenarios and future periods. These findings highlight that the Jemma River's future flow regime is likely to be significantly influenced by climate change. Sensitivity analysis further demonstrated that projected streamflow is more responsive to variations in rainfall than to changes in PET or temperature across all scenarios.
Abstract: Understanding the potential impacts of climate change on hydrological processes and water resources at regional and local scales is essential for developing effective adaptation strategies. This study evaluates the projected effects of climate change on the Jemma River Basin, located in the Upper Blue Nile region of Ethiopia, using future climate d...
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