Investigating the Vulnerability ofHydropower Generation Due to Impact ofClimate Change, Tana Beles, Ethiopia

Abstract

The increased use of renewable energy is critical to reducing emissions of greenhouse gases in order to limit climatic change. Hydropower is currently the major renewable source contributing toelectricitysupply. However, the successful expansion of hydropower is dependent on the availability ofthe resource. Global warming and changes in precipitation patternswill alter the timing and magnitude ofriverflows. This will affect the ability of hydropower stationsto harness the resource, and may reduce production. This study mainly deals with the vulnerability of Tana-Beles hydropower station due to climate change impact. In which its performance is evaluated based on the reliability, resilience and vulnerability indices(RRV-criteria) on thelake reservoir controlled by Chara-Chara weir. Projection ofthe future climate variables is done by using General Circulation Model (GCM) withECHAM driving data source which is considered as the most advanced tool for estimating the future climatic condition. Regional Down Scaling Method (RegCM3) is applied in order to downscale the climate variables at catchment level (Downscaled climate data source, IWMI). The projected future climate variable shows an increasing trend for both maximum andminimum temperature however, for the case precipitation itdoesn’t manifest a systematic increase or decreasing trend in the next century. The evaporation fromthe open water surface of reservoir reveals an average annual increase by 5.9 % and 14.6% in 2030sand 2090s respectively under the ECHAM5 A1B emission scenario. The averaged mean annual Lake precipitation is increased by 2.6% and 5.3% while the average annual maximum temperature is rise by 1.2 0 C and 2.2 0 c, average annual minimum temperature is rise by1.6 0 c and 4.48 0 c in 2030s and 2090s respectively. A hydrological model, HBV was utilized to simulate thewater balance. The performance of the model was assessed through calibration and validation process and averagely resulted NS value of 0.7 for gauged catchments. The simulated average annual inflow to the lake shows that a decrease in volume by 2.1% and 14.3% in the scenario years of 2030s and 2090s. Under ECHAM5, A1B scenario out puts the average dimensionless vulnerability index evaluated to be 16.9% in the future time periods which is indicates the Tana-Beles hydropower station is less vulnerable to climate change impact.