Impact of drought on hydropower generation in the Volta River basin and future projections under different climate and development pathways

Abstract

Hydropower is a major electricity source for Ghana, supplying about 28 % of the national generation capacity. Looking to the future, Ghana's vulnerability to drought may intensify with climate change projections in the Volta Basin indicating higher temperatures, more frequent extreme weather events and greater rainfall variability, which could exacerbate drought risks, alter river flow and disrupt electricity production from dams. This poses major energy security concerns for Ghana, which depends heavily on hydropower and has limited capacity to adapt. Therefore, this study evaluated the potential impacts of future droughts, measured by the Standardized Precipitation Evapotranspiration Index (SPEI), on hydropower generation and electricity pricing in Ghana under different Shared Socioeconomic Pathway (SSP) scenarios. A statistically significant Random Forest Regression model driven by SPEI projections was developed to forecast hydropower output from Ghana's largest hydropower plant, the Akosombo Dam, through 2050. Results indicate drought risks across SSPs, with more frequent hydropower generation deficits compared to optimal historical baseline averages. As generation fluctuates, electricity prices are forecast to continue rising substantially, although favourable socioeconomic pathways like SSP1 can limit price spikes. The findings underscore the importance of diversifying Ghana's electricity mix and implementing climate adaptation measures to hedge against increasing uncertainty in hydropower resources. The insights provide vital information to guide power sector planning and policies to build climate resilience.