Assessment uf Climate Change Impact on Baro-Akobo River Basin Reservoirs (A Case Study on Baro-I and Baro-II Multipurpose Reservoirs, Ethiopia)

Abstract

This study assesses the impact of future climate change on the Baro-Akobo river basin reservoirs in particular to Baro-1 and Baro-2 reservoirs which are going to be implemented in the near future. The study focuses on their capabilities to hydropower generation under future climate change. To know the level of impact of climate change on the reservoirs. water availability and power generation potential, climate change scenarios of precipitation and evapotranspiration were developed for two future periods of 30 years from the year 2021 until 2080. The ERA-40 re-analysis predictor variables data was used to develop the downscaling models. The outputs of ECHAM5 coupled atmosphere-ocean GCM model for the A2 SRES emission scenarios were used to produce the future scenarios. These outputs were statistically downscaled to the watershed scale through developed regression models. Monthly water balance model was used to simulate inflows to the reservoirs. The performance of the model was assessed through calibration and validation process and the R2 resulted from 0.66 to 0.75 during calibration and from 0.64 to 0.72 during validation at the two gauging stations. The simulated inflows were used to simulate the hydro power potential of the reservoirs using WEAP model for further impact assessments. The generated future scenario for precipitation showed an annual increment at the three stations in the study area. At monthly level the precipitation amount showed an increasing trend in all months except in the months of March and June. Generally higher increment of average monthly precipitation amount observed during the dry season as compared to the main rainy season. Comparison of the base period and the future period average annual inflow volume showed an increase of 4.78% during the 2021-2050 period and 10.66% during the 2051-2080 period at Baro-I reservoir. At Baro-2 reservoir, an increase of 4.83 % during the 2021-2050 period and 10.74% during the 2051-2080 period and at Genji an_nual power generation might increase by 2.3% and in the period 2051-2080 it might also increase by 4.3 % in comparison to the base period at Baro-2 hydropower station.