Assessing the impacts of climate change on streamflow in the upper Omo Gibe basin of Southwest Ethiopia using MIKE NAM

ABSTRACT

Climate change affecting the rainfall-runoff processes in the upper Omo Gibe river basin was articulated using bias-corrected ensemble simulations of the CORDEX-Africa under RCP4.5 and RCP8.5 climatic scenarios. CMhyd was used to downscale the ensembles statistically followed by bias-adjustment using distribution mapping. MIKE NAM model was used (1980-2005) to project streamflow for three time periods; the near future (2023-2048), the middle future (2049-2074), and the far future (2075-2100). The average temperature of the basin will rise by 1.59°C and 2.56°C, respectively, under RCP4.5 and RCP8.5, respectively, while, the precipitation for wet and dry seasons decreases by 7.97% and 23.67%, respectively. MIKE NAM has demonstrated a strong correlation between simulated and observed runoff with coefficients of determination (R2) and NSE of more than 0.75. It has been predicted that the mean dry season, wet season, and annual streamflow will decline by 15-27%, 4-13%, and 8-24%, respectively. Intricate study of climate change followed by judicious and timely precautionary measures if not taken today, will decrease in streamflow and put negative consequences on long-term irrigation and hydropower development in the river catchment of upper Omo Gibe basin.

KEYWORDS:

• Climate change
• streamflow
• CORDEX-Africa
• RCP scenario
• MIKE NAM model

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Kindie Zewdie Werede

Kindie Zewdie Werede is a PhD Scholar in Hydraulic Engineering, Arba Minch Water Technology Institute, Arba Minch University, Ethiopia.

Tarun Kumar Lohani

Tarun Kumar Lohani is working as professor in Hydraulic and Water resources Engineering, Arba Minch Water Technology Institute, Arba Minch University, Ethiopia.

Bogale Gebremariam Neka

Bogale Gebremariam Neka serving as Associate Professor in Hydraulic and Water resources Engineering, Arba Minch Water Technology Institute, Arba Minch University, Ethiopia.

Getachew Bereta Geremew

Getachew Bereta Geremew works as Assistant Professor in Hydraulic and Water resources Engineering, Arba Minch Water Technology Institute, Arba Minch University, Ethiopia.