Response of climate change impact on streamflow: the case of the Upper Awash sub-basin, Ethiopia

Abstract

This paper discusses the response of climate change impact on future streamflow availability in Upper Awash River basin, Ethiopia. The change of climate was built using the CORDEX, RCM daily precipitation, maximum and minimum temperature under RCP4.5 and 8.5 scenarios. The climate model was examined in the historical period 1996–2015 for its ability to capture observed precipitation and temperature. Bias correction was performed on RCM temperature and precipitation to minimize the uncertainties that may occur from climate model projection. After the successful calibration and validation of the HBV hydrological model, streamflow was simulated for the periods of 2021–2040 and 2041–2060 and compared to streamflow of the baseline period 1996–2015 to investigate the changes. The results suggested that overall, following the precipitation increment, streamflow is expected to increase under both RCPs. The average monthly changes of streamflow are expected to increase by 40.1 and 29.4% under RCP4.5 and 16.9 and 18.5% under RCP8.5 scenarios for 2021–2040 and 2041–2060, respectively. Annual streamflow would increase by 28.5 and 23.95% under RCP4.5 and 8.5, respectively. The results of this work can help and inform the water resources planner and designer to frame an appropriate plan and management for the effective use of water in the future.

Investigation of climate change impact on the optimal operation of koka reservoir, upper awash watershed, Ethiopia

“…Thus, a graphical and statistical evaluation of the observed and simulated runoff demonstrated the suitability of the SWAT model for the monthly runoff simulation of the Upper Awash watershed. The probable reasons for the good performance of the SWAT model could be (1) the initial watershed parameters for the SWAT model were obtained from previously calibrated hydrological models [ 17 , 22 , 25 , 29 , 47 ] in the Upper Awash watershed and on the entire Awash basin. (2) The SCS-CN method has been proved to perform better in Agricultural watersheds.…”

“…This is a typical weakness for most hydrological models which may be related to an underlying assumption used in developing the model. For instance, Adera and Alfredsen [ 16 ]; Abdulahi et al [ 25 ], and Heyi and Dinka [ 29 ]stated that the HVB model caused a significant difference between the simulated and observed upper extreme values and the model had better performed in predicting the medium-range flow. According to Kannan [ 55 ] and Halwatura and Najim [ 56 ], the effectiveness of the SCS-CN method was experimentally tested in a small agricultural watershed in the mid-western United States.…”

“…The first four RCMs are forced by ICHEC-EC-EARTH, whereas the last RCM (CanRCM4) is forced by CCCma.CCCma-CanESM2. According to previous studies conducted in the different climatic zones of Ethiopia [ 19 , 25 , 36 , 37 ], the performance of the selected RCMs is adequate and acceptable.…”

“…Recently, climate change has caused the watershed to experience frequent floods, droughts, and seasonal rainfall shifts [ 22 ]. The projected impact of climate change in the Upper Awash watershed also showed that it is expected to have a greater magnitude and direction than the influence already seen over the past three decades [ [22] , [23] , [24] , [25] ].…”

“…The impact of climate change on the water resources of Upper Awash watershed is indicated by Previous studies [ 22 , 25 ]. To the best knowledge of the authors, the hydropower capacity and optimal operation of Koka reservoir in the face of climate change is not studied yet.…”