Interannual climate variability and hydropower generation sensitivity at Ruacana station with implications for energy security in Namibia

Abstract Hydropower at the Ruacana station underpins Namibia’s domestic electricity supply; however, empirical evidence of how interannual climate variability influences its performance remains limited. This study quantified the sensitivity of Ruacana’s annual electricity generation to upstream climatic conditions from 1991 to 2023 using an Ordinary Least Squares (OLS) approach and annual rainfall and potential evapotranspiration (PET) data. The results show that rainfall is the dominant climatic driver of hydropower output; a 1% increase in basin rainfall is associated with a 0.56% increase in annual generation, which is significant at the 5% level (p = 0.036). PET had no statistically significant effect on the output. These findings demonstrate Ruacana’s vulnerability to rainfall fluctuations and highlight the implications for Namibia’s energy security, particularly in dry years. This study provides plant-level empirical evidence to inform climate-resilient hydropower planning and cross-border water energy management.