Assessing the Impact of Climate Change on Surface Water Resources Availability: the Case Awash Bello Watershed, Awash basin
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Date
2021-08
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Addis Ababa University
Abstract
The sign of climate change and its impact is revealing on different natural and synthetic systems. The objective of this study was to analyse and quantify the impacts of climate change on stream flow in awash Bello watershed, upper Awash River basin, Ethiopia. Ensemble mean of six Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa regional climate models operating under two alternative scenarios of Representative Concentration Pathways (RCP 4.5 and RCP 8.5) was used. The period from 1990 to 2010 was used for the analysis of the baseline scenario while the periods (2031–2070) and (2071–2100) were used for future scenarios analysis. The impact assessment on stream flow was done using soil and water assessment tool (SWAT) hydrological model. The statistical performance of the SWAT model in simulating the stream flow was shown with coefficient of determination R2 of 0.91, R-Factor of 0.62 and Nash-Sutcliffe Efficiency (NSE) of 0.87 for monthly calibration and R2 of 0.79, R-Factor of 0.56 and ENS of 0.67 for monthly validation periods. Mean monthly changes in precipitation and temperature (maximum and minimum) were used to quantify these impacts. The result of bias-corrected precipitation and temperature disclosed a logical increase in all future periods for both RCP 4.5 and RCP 8.5 scenarios. These changes in climate variables created an increase in mean annual stream flow by 14.5 and 19.1% for RCP 4.5 and by 4.7 and 6.9% for RCP 8.5 scenarios of the 2070s and 2100s, respectively. This result provides valuable information for guiding current and future water resource management in the awash Bello watershed and similar other areas in all awash basin as well as in Ethiopia.
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Climate change, Bias Correction, CORDEX Africa, GCM, RCM, SWAT model