Abstract:
The impact of climate change on streamflow is one of the present-day sensitive issues all over
the world. The main objective of this study was to evaluate the impact of climate change
streamflow in the Mojo River watershed, Upper Awash River basin, Ethiopia. The observed
hydro-meteorological data for the baseline period of 1987-2016 was collected from Ethiopian
Ministry of Water,Irrigation and Energy (MoWIE) and Ethiopian Meteorological Agency
(EMA). Three Regional Climate Models (RCMs),i.e. RACMO22T, RCA4 and CCLM4-8,
derived by one MOHC-HadGEM2-ES Global Climate Model (GCM) were downloaded from
CORDEX-Africa, under representative concentration pathways (RCPs)4.5 and 8.5. Each
climatic parameter was extracted from RCMs using Arc GIS 10.4.1 and the performance of
the model was tested by using r, RMSE, PBIAS, and identified RAMCO22T the better
performed than the other. Bias corrections was done by power transformation for the
precipitation and variance scale for the temperature equation. The trend of precipitation and
temperature was significantly increased and decreasing annually. The simulation was carried
out by using the Soil and Water Assessment Tool (SWAT) model under historical (1987-2016)
and future climatic scenarios that range between (2022-2051) and (2052-2081). Calibration
and validation were performed by using sequential uncertainty fitting version-two (SUFI-2)
algorithm in SWAT CUP program utilizing recorded streamflow data of (2000-2015). The
Performance of the model was evaluated during calibration (R
2 = 0.71, NSE = 0.70, PBAIS =
-13.9) and validation (R
2 = 0.71, NSE = 0.64, PBAIS = -4.7). The projected mean annual
maximum temperature showed an increasing trend in the future period (2022-2051), and (2052
- 2081) periods under RCP4.5 by 0.14℃ and 0.7℃, and RCP8.5 scenarios by 0.4℃ and 1.3℃
respectively. Whereas, the minimum temperature will be decreasing by (-1.1 and -0.7) for
(2022-2051) and increasing by (1.3 and 1.3) for (2052-2081) periods under RCP4.5 and
RCP8.5 scenarios respectively. The annual streamflow will increase by 55% and 57.07%
under RCP4.5, and by 55.8% and 58% under RCP8.5 with the future periods of (2051), and
(2081) respectively
