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
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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Research Article
Determination of Irrigation Interval and Optimum Water Demand of Wheat at Eastern Hararghe zone of Oromia
Lalisa Ofga*,
Jemal Nur
Issue:
Volume 13, Issue 3, September 2025
Pages:
200-205
Received:
21 August 2025
Accepted:
23 September 2025
Published:
18 October 2025
DOI:
10.11648/j.hyd.20251303.12
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Abstract: Soil moisture based application of irrigation water is crucial for obtaining optimum irrigation scheduling of crop. The objectives of this study were determining optimum irrigation interval, irrigation frequency and optimum water demand of wheat for better production. The result indicates that maximum irrigation frequency and maximum irrigation water was applied by 60% ASMDL. Minimum irrigation frequency and minimum water was applied by 140% ASMDL treatment. A narrow irrigation interval was applied by 60% ASMDL and elongated irrigation interval was applied by 140% ASMDL. The result show that, maximum plant height, number of productive tillers, straw yield and grain yield was obtained by 60% ASMDL treatment. The result indicates that, statistically there is no significance difference between 80% ASMDL and 60% ASMDL treatments in terms of wheat grain yield. The result implies that, as irrigation water is applied more frequently and in short interval the wheat produce more tiller which leads to maximum grain yield. Maximum water productivity (2.078 kg/m3) was obtained by scheduling irrigation at 100% ASMDL. Statistically there is no significance difference between 80% ASMDL and 100% ASMDL in terms of water productivity. Minimum water productivity was obtained by scheduling irrigation at 140% ASMDL. The result show that, optimum grain yield (41.69 qt/ha) and optimum water productivity (2.001 kg/m3) was obtained by scheduling irrigation at 80% ASMDL treatment than others. The lowest grain wheat yield (26.44 qt/ha) and lowest water productivity (1.716 kg/ha) was obtained by scheduling irrigation at 140% ASMDL treatment. Therefore, scheduling irrigation at 80% ASMDL (at p=0.4) has been recommended for wheat with 5 day, 7 day, 5 day and 12 day irrigation interval at initial, development, mid and maturity stage of wheat respectively in the study area and same agro-ecology.
Abstract: Soil moisture based application of irrigation water is crucial for obtaining optimum irrigation scheduling of crop. The objectives of this study were determining optimum irrigation interval, irrigation frequency and optimum water demand of wheat for better production. The result indicates that maximum irrigation frequency and maximum irrigation wat...
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