The trade-offs in re-operating dams for the environment in the Lower Volta River Basin

The construction of the Akosombo dam in the Lower Volta River basin in Ghana led to the formation of the largest artificial lake by surface area and the resettlement of 80,000 people. As a consequence, the riverine ecosystem changed, as did the lives of the downstream communities who lost their traditional livelihoods. These costs are in contrast to the vast economic benefits that Ghana as a whole has enjoyed from the affordable hydropower, irrigation schemes and lake tourism that have developed after construction of the dam. The Akosombo dam is credited for powering Ghana’s industrialization and making it one of the more developed countries in West Africa. Herein lies the crux of the matter: there are trade-offs between anthropogenic water demands and water for ecosystems which provide important ecosystem services, particularly for riverine communities. A transparent and justifiable approach to dam operation is needed to manage these trade-offs between multiple water users. In this study, Evolutionary Multi-Objective Direct Policy Search (EMODPS) is used to identify the multi-sectorial trade-offs in the Lower Volta River Basin. A designer environmental flow is incorporated as an objective rather than as a constraint and additionally, different policy framings as well as future scenarios encompassing climate change and varying energy futures are investigated. This study not only highlights the challenges faced by dam operators in balancing anthropogenic water demands and environmental considerations, but also identifies opportunities for compromises in the Lower Volta River.